ORCID Profile
0000-0001-9953-6806
Current Organisations
Institut de Recherche pour le Développement
,
CSIRO
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Research Topics
In Research Link Australia (RLA), "Research Topics" refer to ANZSRC FOR and SEO codes. These topics are either sourced from ANZSRC FOR and SEO codes listed in researchers' related grants or generated by a large language model (LLM) based on their publications.
Top 5 Research Topics
ANZSRC Field of Research (FoR)
Atmospheric Sciences | Atmospheric Dynamics | Atmospheric Aerosols | Cloud Physics | Physical Oceanography | Glaciology | Climatology (excl. Climate Change Processes) | Climate Change Processes | Other Chemical Sciences | Environmental Engineering not elsewhere classified | Environmental Chemistry (incl. Atmospheric Chemistry) | Maritime Engineering | Environmental Monitoring | Ocean Engineering | Atmospheric Sciences not elsewhere classified |
ANZSRC Socio-Economic Objective (SEO)
Atmospheric Processes and Dynamics | Atmospheric Composition (incl. Greenhouse Gas Inventory) | Effects of Climate Change and Variability on Antarctic and Sub-Antarctic Environments (excl. Social Impacts) | Ecosystem Adaptation to Climate Change | Weather | Climate Variability (excl. Social Impacts) | Climate Change Models | Antarctic and Sub-Antarctic Air Quality | Antarctic and Sub-Antarctic Oceanography | Ground Transport not elsewhere classified | Air Quality not elsewhere classified | Environmental Health
Related Links
Publications
Biomass burning and biogenic aerosols in northern Australia during the SAFIRED campaign
Publisher: Copernicus GmbH
Date: 23-03-2017
Abstract: Abstract. There is a lack of knowledge of how biomass burning aerosols in the tropics age, including those in the fire-prone Northern Territory in Australia. This paper reports chemical characterization of fresh and aged aerosols monitored during the 1-month-long SAFIRED (Savannah Fires in the Early Dry Season) field study, with an emphasis on the chemical signature and aging of organic aerosols. The c aign took place in June 2014 during the early dry season when the surface measurement site, the Australian Tropical Atmospheric Research Station (ATARS), located in the Northern Territory, was heavily influenced by thousands of wild and prescribed bushfires. ATARS was equipped with a wide suite of instrumentation for gaseous and aerosol characterization. A compact time-of-flight aerosol mass spectrometer was deployed to monitor aerosol chemical composition. Approximately 90 % of submicron non-refractory mass was composed of organic material. Ozone enhancement in biomass burning plumes indicated increased air mass photochemistry. The ersity in biomass burning emissions was illustrated through variability in chemical signature (e.g. wide range in f44, from 0.06 to 0.18) for five intense fire events. The background particulate loading was characterized using positive matrix factorization (PMF). A PMF-resolved BBOA (biomass burning organic aerosol) factor comprised 24 % of the submicron non-refractory organic aerosol mass, confirming the significance of fire sources. A dominant PMF factor, OOA (oxygenated organic aerosol), made up 47 % of the s led aerosol, illustrating the importance of aerosol aging in the Northern Territory. Biogenic isoprene-derived organic aerosol factor was the third significant fraction of the background aerosol (28 %).
Spatial distribution of selected persistent organic pollutants (POPs) in Australia's atmosphere
Publisher: Royal Society of Chemistry (RSC)
Date: 2015
DOI: 10.1039/C4EM00594E
Abstract: Systematic data for atmospheric POPs and their spatial variations across Australia are presented for the first time.
Measurement Report: Real-Time Remote Sensing of the Coastal Boundary Layer and its Interaction with Meteorology at Cape Grim, Australia
Publisher: Copernicus GmbH
Date: 09-03-2022
DOI: 10.5194/ACP-2022-104
Abstract: Abstract. Despite considerable efforts during the last decade, real-time characterization of the marine boundary layer and aerosol optical properties over the Southern Ocean remains scarce. We conducted simultaneous measurements of the marine boundary layer utilizing a synergy of remote sensing technology at the Baseline Air Pollution Station at Cape Grim in northwestern Tasmania, Australia, from 14 May to 16 July 2019. Aerosol optical properties were monitored by lidar (miniMPL) and a ceilometer to identify the boundary layer height, and sodar provided wind profiles to investigate their influences on the layer evolution. Boundary layer heights simulated using the Weather Research and Forecasting (WRF) model were also employed for comparison purposes. Through complementary analyses of three cases representing different source influences (marine, sea breeze and continental), this paper evaluates two algorithms (Image Edge Detection Algorithm (IEDA) and gradient method) for boundary layer height detection and examines the vertical aerosol distribution within the boundary layer at Cape Grim with an emphasis on the contributions of regional and local meteorology. We found IEDA generally performed better than the gradient method, especially during the marine-flow-influenced period with a convective layer structure. Different features of boundary layer structures in three episodes, including differential boundary layer growth and interaction with wind evolutionary processes were investigated. One was characterized by a diurnal variation with a boundary layer height of approximately 0.2–0.5 km, associated with the veering of the wind vector within the marine boundary layer during the development of a sea breeze. The other showed a thermally stable layer below 0.3 km with an enhanced extinction coefficient and linear depolarization ratio under the influence of continental sources, which was also validated by the observation from Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation (CALIPSO) satellite. The increasing extinction coefficient and depolarization ratio with wind speeds may be attributed to the increased wet sea salt production and regional transportation from mainland Australia.
Particle phase acidity and oligomer formation in secondary organic aerosol
Publisher: American Chemical Society (ACS)
Date: 12-11-2004
DOI: 10.1021/ES049125K
Abstract: A series of controlled laboratory experiments are carried out in dual Teflon chambers to examine the presence of oligomers in secondary organic aerosols (SOA) from hydrocarbon ozonolysis as well as to explore the effect of particle phase acidity on SOA formation. In all seven hydrocarbon systems studied (i.e., alpha-pinene, cyclohexene, 1-methyl cyclopentene, cycloheptene, 1-methyl cyclohexene, cyclooctene, and terpinolene), oligomers with MW from 250 to 1600 are present in the SOA formed, both in the absence and presence of seed particles and regardless of the seed particle acidity. These oligomers are comparable to, and in some cases, exceed the low molecular weight species (MW < 250) in ion intensities in the ion trap mass spectra, suggesting they may comprise a substantial fraction of the total aerosol mass. It is possible that oligomers are widely present in atmospheric organic aerosols, formed through acid- or base-catalyzed heterogeneous reactions. In addition, as the seed particle acidity increases, larger oligomers are formed more abundantly in the SOA consequently, the overall SOA yield also increases. This explicit effect of particle phase acidity on the composition and yield of SOA may have important climatic consequences and need to be considered in relevant models.
Measurement report: Understanding the seasonal cycle of Southern Ocean aerosols
Publisher: Copernicus GmbH
Date: 29-03-2023
Abstract: Abstract. The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the summer season are typically limited to long-term stations, such as Kennaook / Cape Grim (KCG 40.7∘ S, 144.7∘ E), which is situated in the northern latitudes of the Southern Ocean, and Antarctic research stations, such as the Japanese operated Syowa (SYO 69.0∘ S, 39.6∘ E). Measurements in the midlatitudes of the Southern Ocean are important, particularly in light of recent observations that highlighted the latitudinal gradient that exists across the region in summertime. Here we present 2 years (March 2016–March 2018) of observations from Macquarie Island (MQI 54.5∘ S, 159.0∘ E) of aerosol (condensation nuclei larger than 10 nm, CN10) and cloud condensation nuclei (CCN at various supersaturations) concentrations. This important multi-year data set is characterised, and its features are compared with the long-term data sets from KCG and SYO together with those from recent, regionally relevant voyages. CN10 concentrations were the highest at KCG by a factor of ∼50 % across all non-winter seasons compared to the other two stations, which were similar (summer medians of 530, 426 and 468 cm−3 at KCG, MQI and SYO, respectively). In wintertime, seasonal minima at KCG and MQI were similar (142 and 152 cm−3, respectively), with SYO being distinctly lower (87 cm−3), likely the result of the reduction in sea spray aerosol generation due to the sea ice ocean cover around the site. CN10 seasonal maxima were observed at the stations at different times of year, with KCG and MQI exhibiting January maxima and SYO having a distinct February high. Comparison of CCN0.5 data between KCG and MQI showed similar overall trends with summertime maxima and wintertime minima however, KCG exhibited slightly (∼10 %) higher concentrations in summer (medians of 158 and 145 cm−3, respectively), whereas KCG showed ∼40 % lower concentrations than MQI in winter (medians of 57 and 92 cm−3, respectively). Spatial and temporal trends in the data were analysed further by contrasting data to coincident observations that occurred aboard several voyages of the RSV Aurora Australis and the RV Investigator. Results from this study are important for validating and improving our models and highlight the heterogeneity of this pristine region and the need for further long-term observations that capture the seasonal cycles.
Seasonal in situ observations of glyoxal and methylglyoxal over the temperate oceans of the Southern Hemisphere
Publisher: Copernicus GmbH
Date: 25-08-2014
DOI: 10.5194/ACPD-14-21659-2014
Abstract: Abstract. Dicarbonyls glyoxal and methylglyoxal have been measured with 2,4-dinitrophenylhydrazine (2,4-DNPH) cartridges and high performance liquid chromatography (HPLC), optimised for dicarbonyl detection, in clean marine air over the temperate Southern Hemisphere (SH) oceans. Measurements of a range of dicarbonyl precursors (volatile organic compounds, VOCs) were made in parallel. These are the first in situ measurements of glyoxal and methylglyoxal over the remote temperate oceans. Six 24 h s les were collected in late summer (February–March) over the Chatham Rise in the South West Pacific Ocean during the Surface Ocean Aerosol Production (SOAP) voyage in 2012, while 34 24 h s les were collected at Cape Grim Baseline Air Pollution Station in late winter (August–September) 2011. Average glyoxal mixing ratios in clean marine air were 7 ppt at Cape Grim, and 24 ppt over Chatham Rise. Average methylglyoxal mixing ratios in clean marine air were 28 ppt at Cape Grim and 12 ppt over Chatham Rise. The mixing ratios of glyoxal at Cape Grim are the lowest observed over the remote oceans, while mixing ratios over Chatham Rise are in good agreement with other temperate and tropical observations, including concurrent MAX-DOAS observations. Methylglyoxal mixing ratios at both sites are comparable to the only other marine methylglyoxal observations available over the tropical Northern Hemisphere (NH) ocean. Ratios of glyoxal : methylglyoxal 1 over Chatham Rise but 1 at Cape Grim, suggesting different formation and/or loss processes or rates dominate at each site. Dicarbonyl precursor VOCs, including isoprene and monoterpenes, are used to calculate an upper estimate yield of glyoxal and methylglyoxal in the remote marine boundary layer and explain at most 1–3 ppt of dicarbonyls observed, corresponding to 11 and 17% of the observed glyoxal and 28 and 10% of the methylglyoxal at Chatham Rise and Cape Grim, respectively, highlighting a significant but as yet unknown production mechanism. Glyoxal surface observations from both sites were converted to vertical columns and compared to average vertical column densities (VCDs) from GOME-2 satellite retrievals. Both satellite columns and in situ observations are higher in summer than winter, however satellite vertical column densities exceeded the surface observations by more than 1.5 × 1014 molecules cm−2 at both sites. This discrepancy may be due to the incorrect assumption that all glyoxal observed by satellite is within the boundary layer, or may be due to challenges retrieving low VCDs of glyoxal over the oceans due to interferences by liquid water absorption, or use of an inappropriate normalisation reference value in the retrieval algorithm. This study provides much needed data to verify the presence of these short lived gases over the remote ocean and provide further evidence of an as yet unidentified source of both glyoxal and also methylglyoxal over the remote oceans.
Multidecadal trend analysis of in situ aerosol radiative properties around the world
Publisher: Copernicus GmbH
Date: 27-07-2020
Abstract: Abstract. In order to assess the evolution of aerosol parameters affecting climate change, a long-term trend analysis of aerosol optical properties was performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann–Kendall (MK) statistical test associated with several pre-whitening methods and with Sen's slope was used as the main trend analysis method. Comparisons with general least mean square associated with autoregressive bootstrap (GLS/ARB) and with standard least mean square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficient trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficient time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, eastern/northern Europe and the Arctic, 22 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 26 % of sites have trends which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10-year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10-year trends are primarily found for earlier periods (10-year trends ending in 2010–2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10-year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10-year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10-year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2009–2012 for all stations in the eastern and central USA. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage provides insight into potential aerosol effects on climate changes.
Cloud condensation Nuclei over the Southern Ocean: wind dependence and seasonal cycles
Publisher: Copernicus GmbH
Date: 25-11-2016
DOI: 10.5194/ACP-2016-998
Abstract: Abstract. Multi-decadal observations of aerosol microphysical properties from regionally representative sites can be used to challenge regional or global numerical models that simulate atmospheric aerosol. Presented here is an analysis of multi-decadal observations at Cape Grim (Australia) that characterise production and removal of the background marine aerosol in Southern Ocean marine boundary layer (MBL) on both short-term weather-related and underlying seasonal scales. A trimodal aerosol distribution comprises Aitken nuclei ( 350 nm) modes, with the Aitken mode dominating number concentration. While the integrated particle number in the MBL over the clean Southern Ocean is only weakly dependent on wind speed the different modes in the aerosol size distribution vary in their relationship with windspeed. The balance between a positive wind dependence in the coarse mode and negative dependence in the accumulation/CCN mode leads to a relatively flat wind dependence in summer and moderately strong positive wind dependence in winter. The change-over in wind dependence of these two modes occurs in a very small size range at the mode intersection, indicative of differences in the balance of production and removal in the coarse and accumulation/CCN modes. While a marine biological source of reduced sulfur appears to dominate CCN concentration over the summer months (December to February) other components contribute to CCN over the full annual cycle. Wind-generated coarse mode sea-salt is an important CCN component year round and is the second most important contributor to CCN from autumn through to mid-spring (March to November). A portion of the non-seasonal dependent contributor to CCN can clearly be attributed to wind generated sea-salt with the remaining part potentially being attributed to long range transported material. Under conditions of greater supersaturation, as expected in more convective cyclonic systems and their associated fronts, Aitken mode particles become increasingly important as CCN.
The effect of proximity to major roads on indoor air quality in typical Australian dwellings
Publisher: Elsevier BV
Date: 04-2011
Low-molecular-weight and oligomeric components in secondary organic aerosol from the ozonolysis of cycloalkenes and alpha-pinene
Publisher: American Chemical Society (ACS)
Date: 22-10-2004
DOI: 10.1021/JP047466E
Southern Ocean Cloud Properties Derived From CAPRICORN and MARCUS Data
Publisher: American Geophysical Union (AGU)
Date: 23-02-2021
DOI: 10.1029/2020JD033368
Abstract: The properties of Southern Ocean (SO) liquid phase non precipitating clouds (hereafter clouds) are examined using shipborne data collected during the Measurements of Aerosols, Radiation and Clouds over the Southern Ocean and the Clouds Aerosols Precipitation Radiation and atmospheric Composition Over the SoutheRN ocean I and II c aigns that took place south of Australia during Autumn 2016 and Summer 2017–2018. Cloud properties are derived using data from W‐band radars, lidars, and microwave radiometers using an optimal estimation algorithm. The SO clouds tended to have larger liquid water paths (LWP, 115 ± 117 g m −2 ), smaller effective radii ( r e , 8.7 ± 3 μm), and higher number concentrations ( N d , 90 ± 107 cm −3 ) than typical values of eastern ocean basin stratocumulus. The clouds demonstrated a tendency for the LWP to increase with N d presumably due to precipitation suppression up to N d of approximately 100 cm −3 when mean LWP decreased with increasing N d . Due to higher optical depth, cloud albedos were less susceptible to changes in N d compared to subtropical stratocumulus. The highest latitude clouds of the datasets, observed along and near the Antarctic coast, presented a distinctly bimodal character. One mode had the properties of marine clouds further north. The other mode occurred in an aerosol environment characterized by high cloud condensation nuclei concentrations and elevated sulfate aerosol without obvious continental aerosol markers. These regions of higher cloud condensation nuclei tended to have higher N d , smaller r e and higher LWP suggesting sensitivity of cloud properties to seasonal biogenic aerosol production in the high latitude SO.
Cloud‐Nucleating Particles Over the Southern Ocean in a Changing Climate
Publisher: American Geophysical Union (AGU)
Date: 03-2021
DOI: 10.1029/2020EF001673
Abstract: Stratocumulus clouds over the Southern Ocean have fewer droplets and are more likely to exist in the predominately supercooled phase than clouds at similar temperatures over northern oceans. One likely reason is that this region has few continental and anthropogenic sources of cloud‐nucleating particles that can form droplets and ice. In this work, we present an overview of aerosol particle types over the Southern Ocean, including new measurements made below, in and above clouds in this region. These measurements and others indicate that biogenic sulfur‐based particles .1 μm diameter contribute the majority of cloud condensation nuclei number concentrations in summer. Ice nucleating particles tend to have more organic components, likely from sea‐spray. Both types of cloud nucleating particles may increase in a warming climate likely to have less sea ice, more phytoplankton activity, and stronger winds over the Southern Ocean near Antarctica. Taken together, clouds over the Southern Ocean may become more reflective and partially counter the region's expected albedo decrease due to diminishing sea ice. However, detailed modeling studies are needed to test this hypothesis due to the complexity of ocean‐cloud‐climate feedbacks in the region.
Factors controlling volatile organic compounds in dwellings in Melbourne, Australia
Publisher: Hindawi Limited
Date: 09-04-2016
DOI: 10.1111/INA.12201
Abstract: This study characterized indoor volatile organic compounds (VOCs) and investigated the effects of the dwelling characteristics, building materials, occupant activities, and environmental conditions on indoor VOC concentrations in 40 dwellings located in Melbourne, Australia, in 2008 and 2009. A total of 97 VOCs were identified. Nine VOCs, n-butane, 2-methylbutane, toluene, formaldehyde, acetaldehyde, d-limonene, ethanol, 2-propanol, and acetic acid, accounted for 68% of the sum of all VOCs. The median indoor concentrations of all VOCs were greater than those measured outdoors. The occupant density was positively associated with indoor VOC concentrations via occupant activities, including respiration and combustion. Terpenes were associated with the use of household cleaning and laundry products. A petroleum-like indoor VOC signature of alkanes and aromatics was associated with the proximity of major roads. The indoor VOC concentrations were negatively correlated (P < 0.05) with ventilation. Levels of VOCs in these Australian dwellings were lower than those from previous studies in North America and Europe, probably due to a combination of an ongoing temporal decrease in indoor VOC concentrations and the leakier nature of Australian dwellings.
Size distribution and sources of aerosol in Launceston, Australia, during winter 1997
Publisher: Informa UK Limited
Date: 03-2000
DOI: 10.1080/10473289.2000.10464022
Abstract: As part of a pilot study into the chemical and physical properties of Australian fine particles, a suite of aerosol s les was collected at Ti Tree Bend in Launceston, Tasmania, during June and July 1997. This period represents midwinter in the Southern Hemisphere, a period when aerosol sources in Launceston are dominated by smoke from domestic wood burning. This paper describes the results from this measurement c aign, with the aim of assessing the effect of wood smoke on the chemical and physical characteristics of ambient aerosol. A micro orifice uniform deposit impactor (MOUDI) was used to measure the size distributions of the aerosol from 0.05 to 20 microns aerodynamic diameter. Continuous measurements of fine particle mass were made using a PM2.5 tapered element oscillating microbalance (TEOM) and light scattering coefficients at 530 nm were measured with nephelometers. Mass size distributions tended to be bimodal, with the diameter of the dominant mode tending to smaller sizes with increases in total mass. Non-sea salt potassium and polycyclic aromatic hydrocarbons (PAHs) were used as chemical tracers for wood smoke. Wood smoke was found to increase absolute particle mass (enough to regularly exceed air quality standards), and to concentrate mass in a single mode below 1 micron aerodynamic diameter. The acid-base equilibrium of the aerosol was altered by the wood smoke source, with free acidity hydrogen ion, non-sea salt sulfate, and ammonium concentrations being higher and the concentration of all species, including nitrate (to differing extents), focused in the fine particle size ranges. The wood smoke source also heavily influenced the aerosol scattering efficiency, adding to a strong diurnal cycle in both mass concentration and light scattering.
Current estimates of biogenic emissions from eucalypts uncertain for southeast Australia
Publisher: Copernicus GmbH
Date: 08-06-2016
Abstract: Abstract. The biogenic emissions of isoprene and monoterpenes are one of the main drivers of atmospheric photochemistry, including oxidant and secondary organic aerosol production. In this paper, the emission rates of isoprene and monoterpenes from Australian vegetation are investigated for the first time using the Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGANv2.1) the CSIRO chemical transport model and atmospheric observations of isoprene, monoterpenes and isoprene oxidation products (methacrolein and methyl vinyl ketone). Observations from four field c aigns during three different seasons are used, covering urban, coastal suburban and inland forest areas. The observed concentrations of isoprene and monoterpenes were of a broadly similar magnitude, which may indicate that southeast Australia holds an unusual position where neither chemical species dominates. The model results overestimate the observed atmospheric concentrations of isoprene (up to a factor of 6) and underestimate the monoterpene concentrations (up to a factor of 4). This may occur because the emission rates currently used in MEGANv2.1 for Australia are drawn mainly from young eucalypt trees ( 7 years), which may emit more isoprene than adult trees. There is no single increase/decrease factor for the emissions which suits all seasons and conditions studied. There is a need for further field measurements of in situ isoprene and monoterpene emission fluxes in Australia.
Supplementary material to "Dry season aerosol iron solubility in tropical northern Australia"
Publisher: Copernicus GmbH
Date: 17-06-2016
GISERA Ambient Air Quality in the Surat Basin Overview of study design
Publisher: CSIRO
Date: 2017
A global analysis of climate-relevant aerosol properties retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
Publisher: Copernicus GmbH
Date: 17-08-2020
Abstract: Abstract. Aerosol particles are essential constituents of the Earth's atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence times, resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in situ near-surface segment of the atmospheric observation system. This paper will provide the widest effort so far to document variability of climate-relevant in situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High-quality data from almost 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single-scattering albedo, and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information, including data provision procedures, quality control and analysis, data policy, and usage of the ground-based aerosol measurement network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.
Supplementary material to "Aging of aerosols emitted from biomass burning in northern Australia"
Publisher: Copernicus GmbH
Date: 15-08-2016
Use of portable air cleaners to reduce aerosol transmission on a hospital coronavirus disease 2019 (COVID-19) ward
Publisher: Cambridge University Press (CUP)
Date: 24-06-2021
DOI: 10.1017/ICE.2021.284
Abstract: To study the airflow, transmission, and clearance of aerosols in the clinical spaces of a hospital ward that had been used to care for patients with coronavirus disease 2019 (COVID-19) and to examine the impact of portable air cleaners on aerosol clearance. Observational study. A single ward of a tertiary-care public hospital in Melbourne, Australia. Glycerin-based aerosol was used as a surrogate for respiratory aerosols. The transmission of aerosols from a single patient room into corridors and a nurses’ station in the ward was measured. The rate of clearance of aerosols was measured over time from the patient room, nurses’ station and ward corridors with and without air cleaners [ie, portable high-efficiency particulate air (HEPA) filters]. Aerosols rapidly travelled from the patient room into other parts of the ward. Air cleaners were effective in increasing the clearance of aerosols from the air in clinical spaces and reducing their spread to other areas. With 2 small domestic air cleaners in a single patient room of a hospital ward, 99% of aerosols could be cleared within 5.5 minutes. Air cleaners may be useful in clinical spaces to help reduce the risk of acquisition of respiratory viruses that are transmitted via aerosols. They are easy to deploy and are likely to be cost-effective in a variety of healthcare settings.
Air Pollution From Bushfires and Out-of-hospital Cardiac Arrests in Melbourne, Australia
Publisher: Ovid Technologies (Wolters Kluwer Health)
Date: 2011
Size-resolved mass and chemical properties of dust aerosols from Australia’s Lake Eyre Basin
Publisher: Elsevier BV
Date: 09-2010
Measurement report: Cloud Processes and the Transport of Biological Emissions Regulate Southern Ocean Particle and Cloud Condensation Nuclei Concentrations
Publisher: Copernicus GmbH
Date: 11-09-2020
DOI: 10.5194/ACP-2020-731
Abstract: Abstract. Long-range transport of biogenic emissions from the coast of Antarctica, precipitation scavenging, and cloud processing are the main processes that influence the observed variability in Southern Ocean (SO) marine boundary layer (MBL) condensation nuclei (CN) and cloud condensation nuclei (CCN) concentrations during the austral summer. Airborne particle measurements on the HIAPER GV from north-south transects between Hobart, Tasmania and 62° S during the Southern Ocean Clouds, Radiation Aerosol Transport Experimental Study (SOCRATES) were separated into four regimes comprising combinations of high and low concentrations of CCN and CN. In 5-day HYSPLIT back trajectories, air parcels with elevated CCN concentrations were almost always shown to have crossed the Antarctic coast, a location with elevated phytoplankton emissions relative to the rest of the SO. The presence of high CCN concentrations was also consistent with high cloud fractions over their trajectory, suggesting there was substantial growth of biogenically formed particles through cloud processing. Cases with low cloud fraction, due to the presence of cumulus clouds, had high CN concentrations, consistent with previously reported new particle formation in cumulus outflow regions. Measurements associated with elevated precipitation during the previous 1.5-days of their trajectory had low CCN concentrations indicating CCN were effectively scavenged by precipitation. A course-mode fitting algorithm was used to determine the primary marine aerosol (PMA) contribution which accounted for 0.07 µm) indicated that particle formation occurs more frequently above the MBL however, the growth of recently formed particles typically occurs in the MBL, consistent with cloud processing and the condensation of volatile compound oxidation products. CCN measurements on the R/V Investigator as part of the second Clouds, Aerosols, Precipitation, Radiation and atmospheric Composition Over the southeRn Ocean (CAPRICORN-2) c aign were also conducted during the same period as the SOCRATES study. The R/V Investigator observed elevated CCN concentrations near Australia, likely due to continental and coastal biogenic emissions. The Antarctic coastal source of CCN from the south as well as CCN sources from the mid-latitudes create a latitudinal gradient in CCN concentration with an observed minimum in the SO between 55° S and 60° S. The SOCRATES airborne measurements are not influenced by Australian continental emissions, but still show evidence of elevated CCN concentrations to the south of 60° S, consistent with biogenic coastal emissions. In addition, a latitudinal gradient in the particle composition is observed more hygroscopic particles to the north, consistent with a greater fraction of sea salt from PMA, and more sulfate and organic particles to the south, which are likely from biogenic sources in coastal Antarctica.
Supplementary material to "Biomass burning emissions in north Australia during the early dry season: an overview of the 2014 SAFIRED campaign"
Publisher: Copernicus GmbH
Date: 10-11-2016
Diaterebic acid acetate and diaterpenylic acid acetate: Atmospheric tracers for secondary organic aerosol formation from 1,8-cineole oxidation
Publisher: American Chemical Society (ACS)
Date: 15-12-2009
DOI: 10.1021/ES802141V
Abstract: Detailed organic speciation of summer time PM10 collected in Melbourne, Australia, indicated the presence of numerous monoterpene oxidation products that have previously been reported in the literature. In addition, two highly oxygenated compounds with molecular formulas C9H14O6 (MW 218) and C10H16O6 (MW 232), previously unreported, were detected during a period associated with high temperatures and bushfire smoke. These two compounds were also present in laboratory-produced secondary organic aerosol (SOA) through the reaction of OH radicals with 1,8-cineole (eucalyptol), which is emitted by Eucalyptus trees. The retention times and mass spectral behavior of the highly oxygenated compounds in high-performance liquid chromatography (LC) coupled to electrospray ionization-time-of-flight mass spectrometry (MS) in parallel to ion trap MS of agree perfectly between the ambient s les and the laboratory-produced SOA s les, suggesting that 1,8-cineole is the precursor of the highly oxygenated compounds. The proposed structure of the compound with molecular formula C10H16O6 was confirmed by synthesis of a reference compound. The two novel compounds were identified as diaterebic acid acetate (2-[1-(acetyloxy)-1-methylethyl]succinic acid, C9H14O6) and diaterpenylic acid acetate (3-[1-(acetyloxy)-1-methylethyl]glutaric acid, C10H16O6) based on the consideration of reaction mechanisms, the structure of a reference compound, and the interpretation of mass spectral data. Depending on the experimental conditions, the SOA yields determined in chamber experiments ranged between 16 and 20% for approximately 25 ppb of hydrocarbon consumed. The concentrations of these compounds were as high as 50 ng m(-3) during the summertime in Melbourne. This study demonstrates the importance and influence of local vegetation patterns on SOA chemical composition.
Composition, size and cloud condensation nuclei activity of biomass burning aerosol from north Australian savannah fires
Publisher: Copernicus GmbH
Date: 07-10-2016
DOI: 10.5194/ACP-2016-867
Abstract: Abstract. The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm−3 when frequent and close fires were burning up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 % ± 20 % during the night and 60 % ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0.04 ± 0.03) than during the day (κ = 0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 nm and 200 nm. The photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant over predictions up to ~100 % were observed using AMS and H-TDMA derived hygroscopicities as well as c aign night and day averages. The largest estimations in every case occurred during the night when the small variations in very weakly hygroscopic species corresponded to large variations in the activation diameters. Trade winds carry the smoke generated from these fires over the Timor Sea where aerosol-cloud interactions are likely to be sensitive to changes in CCN concentrations, perturbing cloud albedo and lifetime. Dry season fires in north Australia are therefore potentially very important in cloud processes in this region.
Biomass burning emissions in north Australia during the early dry season: an overview of the 2014 SAFIRED campaign
Publisher: Copernicus GmbH
Date: 10-11-2016
DOI: 10.5194/ACP-2016-866
Abstract: Abstract. The SAFIRED (Savannah Fires in the Early Dry Season) c aign took place from 29th of May, 2014 until the 30th June, 2014 at the Australian Tropical Atmospheric Research Station (ATARS) in the Northern Territory, Australia. The purpose of this c aign was to investigate emissions from fires in the early dry season in northern Australia. Measurements were made of biomass burning aerosols, volatile organic compounds, polycyclic aromatic carbons, greenhouse gases, radon, mercury cycle, and trace metals. Aspects of the biomass burning aerosol emissions investigated included emission factors of various emitted species, physical and chemical aerosol properties, aerosol aging, micronutrient supply to the ocean, nucleation, and aerosol water uptake. Over the course of the month-long c aign, biomass burning signals were prevalent and emissions from several large single burning events were observed at ATARS. Biomass burning emissions dominated the gas and aerosol concentrations in this region. Nine major biomass burning events were identified and associated with intense or close in idual smoke plumes. Dry season fires are extremely frequent and widespread across the northern region of Australia, which suggests that the measured aerosol and gaseous emissions at ATARS are likely representative of signals across the entire region of north Australia. Air mass forward trajectories show that these biomass burning emissions are carried north west over the Timor Sea and could influence the atmosphere over Indonesia and the tropical atmosphere over the Indian Ocean. The outcomes of this c aign will be numerous. This region is an environment with little human impact and provides a unique look into the characteristics of biomass burning aerosol without the influence of other significant emission sources. Relationships between the aerosol physical and chemical properties, gas concentrations and meteorological data for the entire month will provide fundamental knowledge required to understand the influence of early dry season burning in this tropical region on the atmosphere. In this paper we present characteristics of the biomass burning observed at the s ling site and provide an overview of the more specific outcomes of the SAFIRED c aign.
Quantification of secondary organic aerosol in an Australian urban location
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/EN10100
Abstract: Environmental contextParticulate matter is detrimental to human health necessitating air quality standards to ensure that populations are not exposed to harmful levels of air pollutants. We quantified, for the first time in an Australian city, secondary organic aerosol produced in the atmosphere by chemical reactions, and show that it constitutes a significant fraction of the fine particulate matter. Secondary organic aerosol should be considered in regulations to control particulate matter and ozone. AbstractThe contribution of secondary organic aerosol (SOA) to particulate mass (PM) in an Australian urban airshed is quantified for the first time in this work. SOA is estimated indirectly using the elemental carbon tracer method. The contribution of primary organic carbon (OC) to PM is determined using ambient air quality data, which is used to indicate photochemical activity and as a tracer for a general vehicular combustion source. In addition, levoglucosan concentrations were used to determine the contribution of wood heater emissions to primary OC. The contribution of bushfire smoke to primary OC emissions was determined from the organic and elemental carbon (OC/EC) ratios measured in bushfire source s les. The median annual SOA concentration determined in this work was 1.1 µg m–3, representing ~13% of PM2.5 median concentrations on an annual basis (assuming a ratio of organic mass (OM) to OC of 1.6). Significantly higher SOA concentrations were determined when bushfire smoke affected the airshed however, the SOA fraction of PM2.5 was greatest during the autumn and early winter months when the formation of inversions allows build up of particles produced by domestic wood-heater emissions.
Supplementary material to "Summer aerosol measurements over the East Antarctic seasonal ice zone"
Publisher: Copernicus GmbH
Date: 26-11-2020
Development and characterization of 13 new, and cross amplification of 3, polymorphic nuclear microsatellite loci in the common myna (Acridotheres tristis)
Publisher: Springer Science and Business Media LLC
Date: 22-02-2012
Design of a study to assess the potential impacts of hydraulic fracturing on air quality in the vicinity of well sites in the Surat Basin, Queensland (Draft 3 – Revised study design for Combabula site) Milestone of 4.1 of Air, Water and Soil Impacts of Hydraulic Fracturing
Publisher: CSIRO
Date: 2017
Australian dust storms in 2002–2003 and their impact on Southern Ocean biogeochemistry
Publisher: American Geophysical Union (AGU)
Date: 30-04-2010
DOI: 10.1029/2009GB003541
Southern Ocean latitudinal gradients of Cloud Condensation Nuclei
Publisher: Copernicus GmbH
Date: 27-01-2021
Abstract: Abstract. The Southern Ocean region is one of the most pristine in the world, and serves as an important proxy for the pre-industrial atmosphere. Improving our understanding of the natural processes in this region are likely to result in the largest reductions in the uncertainty of climate and earth system models. While remoteness from anthropogenic and continental sources is responsible for its clean atmosphere, this also results in the dearth of atmospheric observations in the region. Here we present a statistical summary of the latitudinal gradient of aerosol and cloud condensation nuclei concentrations obtained from five voyages spanning the Southern Ocean between Australia and Antarctica from late-spring to early autumn (October to March) of the 2017/18 austral seasons. Three main regions of influence were identified: the northern sector (40–45° S) where continental and anthropogenic sources added to the background marine aerosol populations the mid-latitude sector (45–65° S), where the aerosol populations reflected a mixture of biogenic and sea-salt aerosol and the southern sector (65–70° S), south of the atmospheric Polar Front, where sea-salt aerosol concentrations were greatly reduced and aerosol populations were primarily biologically-derived sulfur species with a significant history in the Antarctic free-troposphere. The northern sector showed the highest number concentrations with median (25th to 75th percentiles) CN10 and CCN0:5 concentrations of (388–839) cm−3 and 322 (105–443) cm−3, respectively. Concentrations in the mid-latitudes were typically around 350 cm−3 and 160 cm−3 for CN10 and CCN0:5, respectively. In the southern sector, concentrations rose markedly, reaching 447 (298–446) cm−3 and 232 (186–271) cm−3 for CN10 and CCN0:5, respectively. The aerosol composition in this sector was marked by a distinct drop in sea-salt and increase in both sulfate fraction and absolute concentrations, resulting in a substantially higher CCN0:5 / CN10 activation ratio of 0.8 compared to around 0.4 for mid-latitudes. Long-term measurements at land-based research stations surrounding the Southern Ocean were found to be good representations at their respective latitudes i.e. CCN observations at Cape Grim (40°39'S) corresponded with CCN measurements from northern and mid-latitude sectors, while CN10 observations only corresponded with observations from the northern sector. Measurements from a simultaneous two year c aign at Macquarie Island (54°30'S) were found to represent all aerosol species well. The southern-most latitudes differed significantly from either of these stations and previous work suggests that Antarctic stations on the East Antarctic coastline do not represent the East Antarctic sea-ice latitudes well. Further measurements are needed to capture the long-term, seasonal and longitudinal variability in aerosol processes across the Southern Ocean.
Characteristics of airborne particle number size distributions in a coastal-urban environment
Publisher: Elsevier BV
Date: 08-2018
Multiscale Applications of Two Online-Coupled Meteorology-Chemistry Models during Recent Field Campaigns in Australia, Part II: Comparison of WRF/Chem and WRF/Chem-ROMS and Impacts of Air-Sea Interactions and Boundary Conditions
Publisher: MDPI AG
Date: 20-04-2019
Abstract: Air-sea interactions play an important role in atmospheric circulation and boundary layer conditions through changing convection processes and surface heat fluxes, particularly in coastal areas. These changes can affect the concentrations, distributions, and lifetimes of atmospheric pollutants. In this Part II paper, the performance of the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are intercompared for their applications over quadruple-nested domains in Australia during the three following field c aigns: The Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2) and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). The results are used to evaluate the impact of air-sea interaction representation in WRF/Chem-ROMS on model predictions. At 3, 9, and 27 km resolutions, compared to WRF/Chem, the explicit air-sea interactions in WRF/Chem-ROMS lead to substantial improvements in simulated sea-surface temperature (SST), latent heat fluxes (LHF), and sensible heat fluxes (SHF) over the ocean, in terms of statistics and spatial distributions, during all three field c aigns. The use of finer grid resolutions (3 or 9 km) effectively reduces the biases in these variables during SPS1 and SPS2 by WRF/Chem-ROMS, whereas it further increases these biases for WRF/Chem during all field c aigns. The large differences in SST, LHF, and SHF between the two models lead to different radiative, cloud, meteorological, and chemical predictions. WRF/Chem-ROMS generally performs better in terms of statistics and temporal variations for temperature and relative humidity at 2 m, wind speed and direction at 10 m, and precipitation. The percentage differences in simulated surface concentrations between the two models are mostly in the range of ±10% for CO, OH, and O3, ±25% for HCHO, ±30% for NO2, ±35% for H2O2, ±50% for SO2, ±60% for isoprene and terpenes, ±15% for PM2.5, and ±12% for PM10. WRF/Chem-ROMS at 3 km resolution slightly improves the statistical performance of many surface and column concentrations. WRF/Chem simulations with satellite-constrained boundary conditions (BCONs) improve the spatial distributions and magnitudes of column CO for all field c aigns and slightly improve those of the column NO2 for SPS1 and SPS2, column HCHO for SPS1 and MUMBA, and column O3 for SPS2 at 3 km over the Greater Sydney area. The satellite-constrained chemical BCONs reduce the model biases of surface CO, NO, and O3 predictions at 3 km for all field c aigns, surface PM2.5 predictions at 3 km for SPS1 and MUMBA, and surface PM10 predictions at all grid resolutions for all field c aigns. A more important role of chemical BCONs in the Southern Hemisphere, compared to that in the Northern Hemisphere reported in this work, indicates a crucial need in developing more realistic chemical BCONs for O3 in the relatively clean SH.
Investigation of mercury emissions from burning of Australian eucalypt forest surface fuels using a combustion wind tunnel and field observations
Publisher: Elsevier BV
Date: 04-2019
Atmospheric Trace Metal Deposition near the Great Barrier Reef, Australia
Publisher: MDPI AG
Date: 15-04-2020
Abstract: Aerosols deposited into the Great Barrier Reef (GBR) contain iron (Fe) and other trace metals, which may act as micronutrients or as toxins to this sensitive marine ecosystem. In this paper, we quantified the atmospheric deposition of Fe and investigated aerosol sources in Mission Beach (Queensland) next to the GBR. Leaching experiments were applied to distinguish pools of Fe with regard to its solubility. The labile Fe concentration in aerosols was 2.3–10.6 ng m−3, which is equivalent to 4.9%–11.4% of total Fe and was linked to combustion and biomass burning processes, while total Fe was dominated by crustal sources. A one-day precipitation event provided more soluble iron than the average dry deposition flux, 0.165 and 0.143 μmol m−2 day−1, respectively. Scanning Electron Microscopy indicated that alumina-silicates were the main carriers of total Fe and s les affected by combustion emissions were accompanied by regular round-shaped carbonaceous particulates. Collected aerosols contained significant amounts of Cd, Co, Cu, Mo, Mn, Pb, V, and Zn, which were mostly (47.5%–96.7%) in the labile form. In this study, we provide the first field data on the atmospheric delivery of Fe and other trace metals to the GBR and propose that this is an important delivery mechanism to this region.
Current estimates of biogenic emissions from Eucalypts uncertain for Southeast Australia
Publisher: Copernicus GmbH
Date: 03-2016
DOI: 10.5194/ACP-2016-92
Abstract: Abstract. The biogenic emissions of isoprene and monoterpenes are one of the main drivers of atmospheric photochemistry, including oxidant and secondary organic aerosol production. In this paper, the emission rates of isoprene and monoterpenes from Australian vegetation are investigated for the first time using the Model of Emissions of Gases and Aerosols from Nature version 2.1 (MEGANv2.1), the CSIRO chemical transport model, and atmospheric observations of isoprene, monoterpenes and isoprene oxidation products (methacrolein and methyl-vinyl-ketone). Observations from four field c aigns during three different seasons are used, covering urban, coastal suburban and inland forest areas. The observed concentrations of isoprene and monoterpenes were of a broadly similar magnitude, which may indicate that southeast Australia holds an unusual position where neither chemical species dominates. The model results overestimate the observed atmospheric concentrations of isoprene (up to a factor of 6) and underestimate the monoterpene concentrations (up to a factor of 4). This may occur because the emission rates currently used in MEGANv2.1 for Australia are drawn mainly from young Eucalypt trees ( 7 years), which may emit more isoprene than adult trees. There is no single increase/decrease factor for the emissions which suits all seasons and conditions studied. There is a need for further field measurements of in-situ isoprene and monoterpene emission fluxes in Australia.
Biomass burning emissions in north Australia during the early dry season: an overview of the 2014 SAFIRED campaign
Publisher: Copernicus GmbH
Date: 17-11-2017
DOI: 10.5194/ACP-17-13681-2017
Abstract: Abstract. The SAFIRED (Savannah Fires in the Early Dry Season) c aign took place from 29 May until 30 June 2014 at the Australian Tropical Atmospheric Research Station (ATARS) in the Northern Territory, Australia. The purpose of this c aign was to investigate emissions from fires in the early dry season in northern Australia. Measurements were made of biomass burning aerosols, volatile organic compounds, polycyclic aromatic carbons, greenhouse gases, radon, speciated atmospheric mercury and trace metals. Aspects of the biomass burning aerosol emissions investigated included emission factors of various species, physical and chemical aerosol properties, aerosol aging, micronutrient supply to the ocean, nucleation, and aerosol water uptake. Over the course of the month-long c aign, biomass burning signals were prevalent and emissions from several large single burning events were observed at ATARS.Biomass burning emissions dominated the gas and aerosol concentrations in this region. Dry season fires are extremely frequent and widespread across the northern region of Australia, which suggests that the measured aerosol and gaseous emissions at ATARS are likely representative of signals across the entire region of north Australia. Air mass forward trajectories show that these biomass burning emissions are carried north-west over the Timor Sea and could influence the atmosphere over Indonesia and the tropical atmosphere over the Indian Ocean. Here we present characteristics of the biomass burning observed at the s ling site and provide an overview of the more specific outcomes of the SAFIRED c aign.
Fire in the Air: Biomass Burning Impacts in a Changing Climate
Publisher: Informa UK Limited
Date: 20-10-2011
Aging of aerosols emitted from biomass burning in northern Australia
Publisher: Copernicus GmbH
Date: 15-08-2016
DOI: 10.5194/ACP-2016-730
Abstract: Abstract. There is a lack of knowledge of how biomass burning aerosols in the tropics age, including those in the fire-prone Northern Territory in Australia. This paper reports chemical characterization and aging of aerosols monitored during the one month long SAFIRED (Savannah Fires in the Early Dry Season) field study, with an emphasis on chemical signature and aging of organic aerosols. The c aign took place in June 2014 during the early dry season when the surface measurement site, the Australian Tropical Atmospheric Research Station (ATARS), located in the Northern Territory, was heavily influenced by thousands of wild and prescribed bushfires. ATARS was equipped with a wide suite of instrumentation for gaseous and aerosol characterization. A compact time-of-flight aerosol mass spectrometer was deployed to monitor aerosol chemical composition. Approximately 80 % of submicron carbonaceous mass and 90 % of submicron non-refractory mass was composed of organic material. Ozone enhancement in biomass burning plumes indicated increased air mass photochemistry and increased organic aerosol and particle diameter with the aging parameter (f44) suggested secondary organic aerosol formation. Diversity of biomass burning emissions was illustrated through variability in chemical signature (e.g. wide range in f44, from 0.06 to 0.13) for five intense fire events. The background particulate loading was characterized using Positive Matrix Factorization (PMF). A PMF-resolved BBOA (biomass burning organic aerosol) factor comprised 24 % of the submicron non-refractory organic aerosol mass, confirming the significance of fire sources. A dominant PMF factor, OOA (oxygenated organic aerosol), made up 47 % of s led aerosol fraction, illustrating the importance of aerosol aging in the Northern Territory. Biogenic IEPOX-SOA (isoprene epoxydiols-related secondary organic aerosol) was the third significant fraction of the background aerosol (28 %).
Emission Factors for Selected Semivolatile Organic Chemicals from Burning of Tropical Biomass Fuels and Estimation of Annual Australian Emissions
Publisher: American Chemical Society (ACS)
Date: 21-08-2017
Abstract: This study reveals that open-field biomass burning can be an important source of various semivolatile organic chemicals (SVOCs) to the atmosphere including polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), and a range of pesticides. Emission factors (EFs) for 39 in idual SVOCs are determined from burning of various fuel types that are common in tropical Australia. Emissions of PAHs are found to be sensitive to differences in combustion efficiencies rather than fuel types, reflecting a de novo formation mechanism. In contrast, revolatilization may be important for other SVOCs such as PCBs. On the basis of the EFs determined in this work, estimates of the annual emissions of these SVOCs from Australian bushfires/wildfires are achieved, including, for ex le, ∑PAHs (160 (min)-1100 (max) Mg), ∑PCBs (14-300 kg), ∑PBDEs (8.8-590 kg), α-endosulfan (6.5-200 kg), and chlorpyrifos (up to 1400 kg), as well as dioxin toxic equivalents (TEQs) of ∑dioxin-like-PCBs (0.018-1.4 g). Emissions of SVOCs that are predominantly revolatilized appear to be related to their use history, with higher emissions estimated for chemicals that had a greater historical usage and were banned only recently or are still in use.
Measurement report: Cloud processes and the transport of biological emissions affect southern ocean particle and cloud condensation nuclei concentrations
Publisher: Copernicus GmbH
Date: 05-03-2021
Abstract: Abstract. Long-range transport of biogenic emissions from the coast of Antarctica, precipitation scavenging, and cloud processing are the main processes that influence the observed variability in Southern Ocean (SO) marine boundary layer (MBL) condensation nuclei (CN) and cloud condensation nuclei (CCN) concentrations during the austral summer. Airborne particle measurements on the HIAPER GV from north–south transects between Hobart, Tasmania, and 62∘ S during the Southern Ocean Clouds, Radiation Aerosol Transport Experimental Study (SOCRATES) were separated into four regimes comprising combinations of high and low concentrations of CCN and CN. In 5 d HYSPLIT back trajectories, air parcels with elevated CCN concentrations were almost always shown to have crossed the Antarctic coast, a location with elevated phytoplankton emissions relative to the rest of the SO in the region south of Australia. The presence of high CCN concentrations was also consistent with high cloud fractions over their trajectory, suggesting there was substantial growth of biogenically formed particles through cloud processing. Cases with low cloud fraction, due to the presence of cumulus clouds, had high CN concentrations, consistent with previously reported new particle formation in cumulus outflow regions. Measurements associated with elevated precipitation during the previous 1.5 d of their trajectory had low CCN concentrations indicating CCN were effectively scavenged by precipitation. A coarse-mode fitting algorithm was used to determine the primary marine aerosol (PMA) contribution, which accounted for % of CCN (at 0.3 % supersaturation) and cloud droplet number concentrations. Vertical profiles of CN and large particle concentrations (Dp .07 µm) indicated that particle formation occurs more frequently above the MBL however, the growth of recently formed particles typically occurs in the MBL, consistent with cloud processing and the condensation of volatile compound oxidation products. CCN measurements on the R/V Investigator as part of the second Clouds, Aerosols, Precipitation, Radiation and atmospheric Composition Over the southeRn Ocean (CAPRICORN-2) c aign were also conducted during the same period as the SOCRATES study. The R/V Investigator observed elevated CCN concentrations near Australia, likely due to continental and coastal biogenic emissions. The Antarctic coastal source of CCN from the south, CCN sources from the midlatitudes, and enhanced precipitation sink in the cyclonic circulation between the Ferrel and polar cells (around 60∘ S) create opposing latitudinal gradients in the CCN concentration with an observed minimum in the SO between 55 and 60∘ S. The SOCRATES airborne measurements are not influenced by Australian continental emissions but still show evidence of elevated CCN concentrations to the south of 60∘ S, consistent with biogenic coastal emissions. In addition, a latitudinal gradient in the particle composition, south of the Australian and Tasmanian coasts, is apparent in aerosol hygroscopicity derived from CCN spectra and aerosol particle size distribution. The particles are more hygroscopic to the north, consistent with a greater fraction of sea salt from PMA, and less hygroscopic to the south as there is more sulfate and organic particles originating from biogenic sources in coastal Antarctica.
Size-resolved chemical composition of Australian dust aerosol during winter
Publisher: CSIRO Publishing
Date: 2011
DOI: 10.1071/EN10134
Abstract: Environmental contextMineral dust aerosol is both an efficient scatterer of solar radiation, potentially cooling the planet, and a moderate absorber, potentially warming it: the exact balance is both uncertain, and geographically variable. Australian desert soils are noticeably more reddish than most Northern Hemisphere deserts, most probably a result of enhanced iron mineralogy. This paper contains results from a field c aign designed to increase our understanding of the chemistry of Australian mineral dust aerosol, especially in relation to iron and salt. AbstractAustralia is the dominant source of mineral dust aerosol in the Southern Hemisphere, yet the physical, chemical and optical properties of this aerosol remain poorly understood. Four sets of size-resolved aerosol s les were collected at a site on the edge of the Lake Eyre Basin (LEB), in the south-east dust transport pathway. Back trajectory analysis shows that three s les were sourced from the LEB (one during a rare winter dust storm), and one from coastal regions to the south. All s les were subjected to both ion beam analysis and ion chromatography. A Fe/Al ratio of 0.9 was found, consistent with results from our other c aigns to sites in the LEB, significantly higher than typical Northern Hemisphere values (~0.45–0.6). This confirms the iron-rich character of central Australian soils. Clear evidence of marine advection in the fourth s le was also found, and evidence of chloride depletion by nitric acid in two s les.
Sydney Particle Study- Stage-I: Executive Summary
Publisher: CSIRO
Date: 2012
The accession of chloride to the western half of the Australian continent
Publisher: CSIRO Publishing
Date: 1997
DOI: 10.1071/S97001
Abstract: Chloride concentrations in bulk precipitation, collected from 18 sites in remote areas of Australia over 2 years, exhibit a dependence on distance from the coast that is well described by the sum of 2 exponentials. Various processes are discussed in terms of their contribution to the ‘fast’ and ‘slow’ components of this relationship. A map of chloride accession to the western and central areas of the Australian continent is constructed. Maximum deposition occurs at coastal localities (60–70 kg/ha), decreasing to kg/ha in the interior of the continent. Chloride deposition shows a decrease from south (70 kg/ha) to north ( kg/ha) of the continent, re˚ecting the greater importance of the subpolar marine airmasses in the supply of ionic species to the Australian continent, and the influence of the continental airmass, low in chloride, on salt deposition in northern Australia.
Supplementary material to "Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania, 41° S"
Publisher: Copernicus GmbH
Date: 07-2015
The first 3 years of CSIRO’s Climate Science Centre: Progress and Achievements of the Climate Science Centre (CSC), CSIRO Oceans and Atmosphere
Publisher: CSIRO
Date: 2020
DOI: 10.25919/PZAF-P326
Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols
Publisher: Copernicus GmbH
Date: 27-11-2019
Abstract: Abstract. Cloud-radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation, and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64° S. During the other two episodes, synoptic-scale weather patterns erted air masses across distances greater than 1000 km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93 % of the total number concentration activating as cloud condensation nuclei. In contrast, s ling periods influenced by marine air masses frequently demonstrated a correlation between air mass trajectories over regions of high biological productivity and subsequent enhancement of an Aitken mode centred at approximately 30 nm and contributing an average of 71 % of the total aerosol number concentration. Although these small diameters limited their contribution to cloud condensation nuclei concentrations, Aitken number concentrations and diameters were highly variable. A detailed investigation of the marine air masses revealed that this variability may be attributed to the availability of biogenic precursors, the competing influence of condensation sinks (such as sea spray aerosol) and vertical transport between the marine boundary layer and the free troposphere. This variability of the marine Aitken mode as well as the instances of long-range transport were governed by synoptic-scale weather systems, through their influence on air mass trajectories and both generation and depletion of condensation sinks. These results demonstrate the highly dynamic nature of Southern Ocean aerosol and their complex dependence on both biological productivity and synoptic-scale weather systems.
Spatial sorting drives morphological variation in the invasive bird, acridotheris tristis
Publisher: Public Library of Science (PLoS)
Date: 31-05-2012
Summer aerosol measurements over the East Antarctic seasonal ice zone
Publisher: Copernicus GmbH
Date: 23-06-2021
Abstract: Abstract. Aerosol measurements over the Southern Ocean have been identified as critical to an improved understanding of aerosol–radiation and aerosol–cloud interactions, as there currently exists significant discrepancies between model results and measurements in this region. The atmosphere above the Southern Ocean provides crucial insight into an aerosol regime relatively free from anthropogenic influence, yet its remoteness ensures atmospheric measurements are relatively rare. Here we present observations from the Polar Cell Aerosol Nucleation (PCAN) c aign, hosted aboard the RV Investigator during a summer (January–March) 2017 voyage from Hobart, Australia, to the East Antarctic seasonal sea ice zone. A median particle number concentration (condensation nuclei 3 nm CN3) of 354 (95 % CI 345–363) cm−3 was observed from the voyage. Median cloud condensation nuclei (CCN) concentrations were 167 (95 % CI 158–176) cm−3. Measured particle size distributions suggested that aerosol populations had undergone significant cloud processing. To understand the variability in aerosol observations, measurements were classified by meteorological variables. Wind direction and absolute humidity were used to identify different air masses, and aerosol measurements were compared based on these identifications. CN3 concentrations measured during SE wind directions (median 594 cm−3) were higher than those measured during wind directions from the NW (median 265 cm−3). Increased frequency of measurements from these wind directions suggests the influence of large-scale atmospheric transport mechanisms on the local aerosol population in the boundary layer of the East Antarctic seasonal ice zone. Modelled back trajectories imply different air mass histories for each measurement group, supporting this suggestion. CN3 and CCN concentrations were higher during periods where the absolute humidity was less than 4.3 gH2O/m3, indicative of free tropospheric or Antarctic continental air masses, compared to other periods of the voyage. Increased aerosol concentration in air masses originating close to the Antarctic coastline have been observed in numerous other studies. However, the smaller changes observed in the present analyses suggest seasonal differences in atmospheric circulation, including lesser impact of synoptic low-pressure systems in summer. Further measurements in the region are required before a more comprehensive picture of atmospheric circulation in this region can be captured and its influence on local aerosol populations understood.
Impact of smoke from biomass burning on air quality in rural communities in southern Australia
Publisher: Elsevier BV
Date: 08-2011
Urban Air Quality in a Coastal City: Wollongong during the MUMBA Campaign
Publisher: MDPI AG
Date: 17-12-2018
DOI: 10.3390/ATMOS9120500
Abstract: We present findings from the Measurements of Urban, Marine and Biogenic Air (MUMBA) c aign, which took place in the coastal city of Wollongong in New South Wales, Australia. We focus on a few key air quality indicators, along with a comparison to regional scale chemical transport model predictions at a spatial resolution of 1 km by 1 km. We find that the CSIRO chemical transport model provides accurate simulations of ozone concentrations at most times, but underestimates the ozone enhancements that occur during extreme temperature events. The model also meets previously published performance standards for fine particulate matter less than 2.5 microns in diameter (PM2.5), and the larger aerosol fraction (PM10). We explore the observed composition of the atmosphere within this urban air-shed during the MUMBA c aign and discuss the different influences on air quality in the city. Our findings suggest that further improvements to our ability to simulate air quality in this coastal city can be made through more accurate anthropogenic and biogenic emissions inventories and better understanding of the impact of extreme temperatures on air quality. The challenges in modelling air quality within the urban air-shed of Wollongong, including difficulties in accurate simulation of the local meteorology, are likely to be replicated in many other coastal cities in the Southern Hemisphere.
Seasonal in situ observations of glyoxal and methylglyoxal over the temperate oceans of the Southern Hemisphere
Publisher: Copernicus GmbH
Date: 12-01-2015
Abstract: Abstract. The dicarbonyls glyoxal and methylglyoxal have been measured with 2,4-dinitrophenylhydrazine (2,4-DNPH) cartridges and high-performance liquid chromatography (HPLC), optimised for dicarbonyl detection, in clean marine air over the temperate Southern Hemisphere (SH) oceans. Measurements of a range of dicarbonyl precursors (volatile organic compounds, VOCs) were made in parallel. These are the first in situ measurements of glyoxal and methylglyoxal over the remote temperate oceans. Six 24 h s les were collected in summer (February–March) over the Chatham Rise in the south-west Pacific Ocean during the Surface Ocean Aerosol Production (SOAP) voyage in 2012, while 34 24 h s les were collected at Cape Grim Baseline Air Pollution Station in the late winter (August–September) of 2011. Average glyoxal mixing ratios in clean marine air were 7 ppt at Cape Grim and 23 ppt over Chatham Rise. Average methylglyoxal mixing ratios in clean marine air were 28 ppt at Cape Grim and 10 ppt over Chatham Rise. The mixing ratios of glyoxal at Cape Grim are the lowest observed over the remote oceans, while mixing ratios over Chatham Rise are in good agreement with other temperate and tropical observations, including concurrent Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations. Methylglyoxal mixing ratios at both sites are comparable to the only other marine methylglyoxal observations available over the tropical Northern Hemisphere (NH) ocean. Ratios of glyoxal : methylglyoxal 1 over Chatham Rise but 1 at Cape Grim suggest that a different formation and/or loss processes or rates dominate at each site. Dicarbonyl precursor VOCs, including isoprene and monoterpenes, are used to calculate an upper-estimate yield of glyoxal and methylglyoxal in the remote marine boundary layer and explain at most 1–3 ppt of dicarbonyls observed, corresponding to 10% and 17% of the observed glyoxal and 29 and 10% of the methylglyoxal at Chatham Rise and Cape Grim, respectively, highlighting a significant but as yet unknown production mechanism. Surface-level glyoxal observations from both sites were converted to vertical columns and compared to average vertical column densities (VCDs) from GOME-2 satellite retrievals. Both satellite columns and in situ observations are higher in summer than winter however, satellite vertical column densities exceeded the surface observations by more than 1.5 × 1014 molecules cm−2 at both sites. This discrepancy may be due to the incorrect assumption that all glyoxal observed by satellite is within the boundary layer, or it may be due to challenges retrieving low VCDs of glyoxal over the oceans due to interferences by liquid water absorption or the use of an inappropriate normalisation reference value in the retrieval algorithm. This study provides much-needed data to verify the presence of these short-lived gases over the remote ocean and provide further evidence of an as yet unidentified source of both glyoxal and also methylglyoxal over the remote oceans.
Measurement Report: Understanding the seasonal cycle of Southern Ocean aerosols
Publisher: Copernicus GmbH
Date: 07-09-2022
DOI: 10.5194/ACP-2022-568
Abstract: Abstract. The remoteness and extreme conditions of the Southern Ocean and Antarctic region have meant that observations in this region are rare, and typically restricted to summertime during research or resupply voyages. Observations of aerosols outside of the summer season are typically limited to long-term stations, such as Kennaook/Cape Grim (KCG, 40.7° S, 144.7° E) which is situated in the northern latitudes of the Southern Ocean, and Antarctic research stations, such as the Japanese operated Syowa (SYO, 69.0° S, 39.6° E). Measurements in the mid-latitudes of the Southern Ocean are important, particularly in light of recent observations that highlighted the latitudinal gradient that exists across the region in summertime. Here we present two years (March 2016–March 2018) of observations from Macquarie Island (MQI, 54.5° S, 159.0° E) of aerosol (condensation nuclei larger than 10 nm, CN10) and cloud condensation nuclei (CCN at various supersaturations) concentrations. This important multi-year data set is characterised, and its features are compared with the long-term data sets from KCG and SYO together with those from recent, regionally relevant voyages. CN10 concentrations were the highest at KCG by a factor of ∼50 % across all non-winter seasons compared to the other two stations which were similar (summer medians of 530 cm-3, 426 cm-3 and 468 cm-3 at KCG, MQI and SYO, respectively). In wintertime, seasonal minima at KCG and MQI were similar (142 cm-3 and 152 cm-3, respectively), with SYO being distinctly lower (87 cm-3), likely the result of the reduction in sea spray aerosol generation due to the sea-ice ocean cover around the site. CN10 seasonal maxima were observed at the stations at different times of year, with KCG and MQI exhibiting January maxima and SYO having a distinct February high. Comparison of CCN0.5 data between KCG and MQI showed similar overall trends with summertime maxima and wintertime minima, however KCG exhibited slightly (∼10 %) higher concentrations in summer (medians of 158 cm-3 and 145 cm-3, respectively), whereas KCG showed ∼40 % lower concentrations than MQI in winter (medians of 57 cm-3 and 92 cm-3, respectively). Spatial and temporal trends in the data were analysed further by contrasting data to coincident observations that occurred aboard several voyages of the RSV Aurora Australis and the RV Investigator. Results from this study are important for validating and improving our models, highlight the heterogeneity of this pristine region, and the need for further long-term observations that capture the seasonal cycles.
Supplementary material to "Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols"
Publisher: Copernicus GmbH
Date: 27-11-2019
The contribution of coral-reef-derived dimethyl sulfide to aerosol burden over the Great Barrier Reef
Publisher: Copernicus GmbH
Date: 22-02-2022
Abstract: Abstract. Coral reefs have been found to produce the sulfur compound dimethyl sulfide (DMS), a climatically relevant aerosol precursor predominantly associated with phytoplankton. Until recently, the role of coral-reef-derived DMS within the climate system had not been quantified. A study preceding the present work found that DMS produced by corals had negligible long-term climatic forcing at the global–regional scale. However, at sub-daily timescales more typically associated with aerosol and cloud formation, the influence of coral-reef-derived DMS on local aerosol radiative effects remains unquantified. The Weather Research and Forecasting model coupled with Chemistry (WRF-Chem) has been used in this work to study the role of coral-reef-derived DMS at sub-daily timescales for the first time. WRF-Chem was run to coincide with an October 2016 field c aign over the Great Barrier Reef, Queensland, Australia, against which the model was evaluated. After updating and scaling the DMS surface water climatology, the model reproduced DMS and sulfur concentrations well. The inclusion of coral-reef-derived DMS resulted in no significant change in sulfate aerosol mass or total aerosol number. Subsequently, no direct or indirect aerosol effects were detected. The results suggest that the co-location of the Great Barrier Reef with significant anthropogenic aerosol sources along the Queensland coast prevents coral-reef-derived aerosol from having a modulating influence on local aerosol burdens in the current climate.
The MUMBA campaign: Measurements of urban, marine and biogenic air
Publisher: Copernicus GmbH
Date: 06-06-2017
Abstract: Abstract. The Measurements of Urban, Marine and Biogenic Air (MUMBA) c aign took place in Wollongong, New South Wales (a small coastal city approximately 80 km south of Sydney, Australia) from 21 December 2012 to 15 February 2013. Like many Australian cities, Wollongong is surrounded by dense eucalyptus forest, so the urban airshed is heavily influenced by biogenic emissions. Instruments were deployed during MUMBA to measure the gaseous and aerosol composition of the atmosphere with the aim of providing a detailed characterisation of the complex environment of the ocean–forest–urban interface that could be used to test the skill of atmospheric models. The gases measured included ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, methane and many of the most abundant volatile organic compounds. The aerosol characterisation included total particle counts above 3 nm, total cloud condensation nuclei counts, mass concentration, number concentration size distribution, aerosol chemical analyses and elemental analysis.The c aign captured varied meteorological conditions, including two extreme heat events, providing a potentially valuable test for models of future air quality in a warmer climate. There was also an episode when the site s led clean marine air for many hours, providing a useful additional measure of the background concentrations of these trace gases within this poorly s led region of the globe. In this paper we describe the c aign, the meteorology and the resulting observations of atmospheric composition in general terms in order to equip the reader with a sufficient understanding of the Wollongong regional influences to use the MUMBA datasets as a case study for testing a chemical transport model. The data are available from PANGAEA (doi.pangaea.de/10.1594/PANGAEA.871982).
Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea ice
Publisher: Copernicus GmbH
Date: 25-02-2016
Abstract: Abstract. Better characterisation of aerosol processes in pristine, natural environments, such as Antarctica, have recently been shown to lead to the largest reduction in uncertainties in our understanding of radiative forcing. Our understanding of aerosols in the Antarctic region is currently based on measurements that are often limited to boundary layer air masses at spatially sparse coastal and continental research stations, with only a handful of studies in the vast sea-ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the icebreaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the polar front, with mean polar cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low-pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air masses quickly from the free troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea-ice boundary layer air masses travelled equatorward into the low-albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei which, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.
Authors Response to Referee 2
Publisher: Copernicus GmbH
Date: 04-08-2019
Gas-phase products and secondary aerosol yields from the ozonolysis of ten different terpenes
Publisher: American Geophysical Union (AGU)
Date: 05-04-2006
DOI: 10.1029/2005JD006437
Hygroscopicity of secondary organic aerosols formed by oxidation of cycloalkenes, monoterpenes, sesquiterpenes, and related compounds
Publisher: Copernicus GmbH
Date: 29-06-2006
Abstract: Abstract. A series of experiments has been conducted in the Caltech indoor smog chamber facility to investigate the water uptake properties of aerosol formed by oxidation of various organic precursors. Secondary organic aerosol (SOA) from simple and substituted cycloalkenes (C5-C8) is produced in dark ozonolysis experiments in a dry chamber (RH~5%). Biogenic SOA from monoterpenes, sesquiterpenes, and oxygenated terpenes is formed by photooxidation in a humid chamber (~50% RH). Using the hygroscopicity tandem differential mobility analyzer (HTDMA), we measure the diameter-based hygroscopic growth factor (GF) of the SOA as a function of time and relative humidity. All SOA studied is found to be slightly hygroscopic, with smaller water uptake than that of typical inorganic aerosol substances. The aerosol water uptake increases with time early in the experiments for the cycloalkene SOA, but decreases with time for the sesquiterpene SOA. This behavior could indicate competing effects between the formation of more highly oxidized polar compounds (more hygroscopic), and formation of longer-chained oligomers (less hygroscopic). All SOA also exhibit a smooth water uptake with RH with no deliquescence or efflorescence. The water uptake curves are found to be fitted well with an empirical three-parameter functional form. The measured pure organic GF values at 85% RH are between 1.09–1.16 for SOA from ozonolysis of cycloalkenes, 1.01–1.04 for sesquiterpene photooxidation SOA, and 1.06–1.10 for the monoterpene and oxygenated terpene SOA. The GF of pure SOA (GForg) in experiments in which inorganic seed aerosol is used is determined by assuming volume-weighted water uptake (Zdanovskii-Stokes-Robinson or "ZSR" approach) and using the size-resolved organic mass fraction measured by the Aerodyne Aerosol Mass Spectrometer. Knowing the water content associated with the inorganic fraction yields GForg values. However, for each precursor, the GForg values computed from different HTDMA-classified diameters agree with each other to varying degrees. Comparing growth factors from different precursors, we find that GForg is inversely proportional to the precursor molecular weight and SOA yield, which is likely a result of the fact that higher-molecular weight precursors tend to produce larger and less hygroscopic oxidation products.
Authors Response to Referee 1
Publisher: Copernicus GmbH
Date: 04-08-2019
Global variability of aerosol optical properties retrieved from the network of GAW near-surface observatories
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-3568
Abstract: & & Atmospheric aerosols are known to play a key role in Earth& #8217 s radiative budget, although the quantification of their climate forcing is still highly uncertain. In order to improve the scientific understanding of their climatic effect, in-situ ground-based aerosol properties observations are needed by the research community. Such data would also allow the global assessment of the effect of environmental policies over both the short and the long term.& & & & To develop a robust and consistent view over time of the worldwide variability of aerosol properties, data resulting from a fully-characterized value chain, including uncertainty estimation, is needed.& & & & The present work is part of a wider project, having among its goals the investigation of the variability of climate-relevant aerosol properties observed at all sites connected to the Global Atmospheric Watch network, whose data are publicly available from the World Data Centre for Aerosols and follow the aforementioned specifications.& & & & This work focuses on aerosol optical proprieties, i.e. the aerosol light scattering coefficient (& #963 & sub& sp& /sub& ), the aerosol light absorption coefficient (& #963 & sub& ap& /sub& ), single scattering albedo (& #969 & sub& o& /sub& ) and both scattering and absorption & #197 ngstr& #246 m exponents (& #229 & sub& sp& /sub& and & #229 & sub& ap& /sub& ).& & & & The analysis includes 108 yearly datasets collected either during 2016 or 2017 at different sites: 53 for absorption and 55 for scattering coefficient datasets, respectively. For 29 of these sites it was also possible to compute single scattering albedo.& & & & The spatial variability in extensive and intensive optical properties was analysed in terms of each site& #8217 s geographical location (either polar, continental, coastal or mountain) and its footprint (from pristine to urban, representing increasing levels of anthropogenic influence).& & & & The results highlight the impact of anthropogenic emissions and biomass burning on absolute levels and annual variability. The effect of sea spray or long range transport of dust is also evident for several sites, along with the influence of regional emissions. The largest seasonality in aerosol loading was observed at mountain sites under mixed footprint conditions, while the lowest seasonality occurred at urban sites. Urban sites also exhibited the highest & #963 sp and & #963 ap values. The lowest levels in & #963 & sub& sp& /sub& and & #963 & sub& ap& /sub& were observed at some polar sites, along with few coastal and mountain sites, despite their typically mixed footprint.& & & & & strong& Acknowledgements& /strong& & & & & The authors acknowledge WMO-GAW World Data Centre on Aerosol for providing data available at ebas.nilu.no& &
Overview of the NOAA/ESRL Federated Aerosol Network
Publisher: American Meteorological Society
Date: 2019
Abstract: To estimate global aerosol radiative forcing, measurements of aerosol optical properties are made by the National Oceanic and Atmospheric Administration (NOAA) Earth System Research Laboratory (ESRL)’s Global Monitoring Division (GMD) and their collaborators at 30 monitoring locations around the world. Many of the sites are located in regions influenced by specific aerosol types (Asian and Saharan desert dust, Asian pollution, biomass burning, etc.). This network of monitoring stations is a shared endeavor of NOAA and many collaborating organizations, including the World Meteorological Organization (WMO)’s Global Atmosphere Watch (GAW) program, the U.S. Department of Energy (DOE), several U.S. and foreign universities, and foreign science organizations. The result is a long-term cooperative program making atmospheric measurements that are directly comparable with those from all the other network stations and with shared data access. The protocols and software developed to support the program facilitate participation in GAW’s atmospheric observation strategy, and the sites in the NOAA/ESRL network make up a substantial subset of the GAW aerosol observations. This paper describes the history of the NOAA/ESRL Federated Aerosol Network, details about measurements and operations, and some recent findings from the network measurements.
Emissions of Selected Semivolatile Organic Chemicals from Forest and Savannah Fires
Publisher: American Chemical Society (ACS)
Date: 18-01-2016
Abstract: The emission factors (EFs) for a broad range of semivolatile organic chemicals (SVOCs) from subtropical eucalypt forest and tropical savannah fires were determined for the first time from in situ investigations. Significantly higher (t test, P < 0.01) EFs (μg kg
The Health Impacts of Ethanol Blend Petrol
Publisher: MDPI AG
Date: 21-02-2011
DOI: 10.3390/EN4020352
Biomass burning at Cape Grim: exploring photochemistry using multi-scale modelling
Publisher: Copernicus GmbH
Date: 05-10-2017
DOI: 10.5194/ACP-17-11707-2017
Abstract: Abstract. We have tested the ability of a high-resolution chemical transport model (CTM) to reproduce biomass burning (BB) plume strikes and ozone (O3) enhancements observed at Cape Grim in Tasmania, Australia, from the Robbins Island fire. The CTM has also been used to explore the contribution of near-field BB emissions and background sources to O3 observations under conditions of complex meteorology. Using atmospheric observations, we have tested model sensitivity to meteorology, BB emission factors (EFs) corresponding to low, medium, and high modified combustion efficiency (MCE), and spatial variability. The use of two different meteorological models (TAPM–CTM and CCAM–CTM) varied the first (BB1) plume strike time by up to 15 h and the duration of impact between 12 and 36 h, and it varied the second (BB2) plume duration between 50 and 57 h. Meteorology also had a large impact on simulated O3, with one model (TAPM–CTM) simulating four periods of O3 enhancement, while the other model (CCAM) simulating only one period. Varying the BB EFs, which in turn varied the non-methane organic compound (NMOC) ∕ oxides of nitrogen (NOx) ratio, had a strongly non-linear impact on simulated O3 concentration, with either destruction or production of O3 predicted in different simulations. As shown in previous work (Lawson et al., 2015), minor rainfall events have the potential to significantly alter EF due to changes in combustion processes. Models that assume fixed EF for O3 precursor species in an environment with temporally or spatially variable EF may be unable to simulate the behaviour of important species such as O3. TAPM–CTM is used to further explore the contribution of the Robbins Island fire to the observed O3 enhancements during BB1 and BB2. Overall, TAPM–CTM suggests that the dominant source of O3 observed at Cape Grim was aged urban air (age = 2 days), with a contribution of O3 formed from local BB emissions. This work shows the importance of assessing model sensitivity to meteorology and EF and the large impact these variables can have in particular on simulated destruction or production of O3 in regional atmospheric chemistry simulations. This work also shows the importance of using models to elucidate the contribution from different sources to atmospheric composition, where this is difficult using observations alone.
Optical, physical and chemical characteristics of Australian continental aerosols: results from a field experiment
Publisher: Copernicus GmbH
Date: 02-07-2010
Abstract: Abstract. Mineral dust is one of the major components of the world's aerosol mix, having a number of impacts within the Earth system. However, the climate forcing impact of mineral dust is currently poorly constrained, with even its sign uncertain. As Australian deserts are more reddish than those in the Northern Hemisphere, it is important to better understand the physical, chemical and optical properties of this important aerosol. We have investigated the properties of Australian desert dust at a site in SW Queensland, which is strongly influenced by both dust and biomass burning aerosol. Three years of ground-based monitoring of spectral optical thickness has provided a statistical picture of gross aerosol properties. The aerosol optical depth data showed a clear though moderate seasonal cycle with an annual mean of 0.06 ± 0.03. The Angstrom coefficient showed a stronger cycle, indicating the influence of the winter-spring burning season in Australia's north. AERONET size distributions showed a generally bimodal character, with the coarse mode assumed to be mineral dust, and the fine mode a mixture of fine dust, biomass burning and marine biogenic material. In November 2006 we undertook a field c aign which collected 4 sets of size-resolved aerosol s les for laboratory analysis – ion beam analysis and ion chromatography. Ion beam analysis was used to determine the elemental composition of all filter s les, although elemental ratios were considered the most reliable output. Scatter plots showed that Fe, Al and Ti were well correlated with Si, and Co reasonably well correlated with Si, with the Fe/Al ratio somewhat higher than values reported from Northern Hemisphere sites (as expected). Scatter plots for Ca, Mn and K against Si showed clear evidence of a second population, which in some cases could be identified with a particular s le day or size fraction. These data may be used to attempt to build a signature of soil in this region of the Australian interior. Ion chromatography was used to quantify water soluble ions for 2 of our s le sets, complementing the picture provided by ion beam analysis. The strong similarities between the MSA and SO42− size distributions argue strongly for a marine origin of much of the SO42−. The similarity of the Na+, Cl− and Mg2+ size distributions also argue for a marine contribution. Further, we believe that both NO3− and NH4+ are the result of surface reactions with appropriate gases.
Observations of the Boundary Layer in the Cape Grim Coastal Region: Interaction with Wind and the Influences of Continental Sources
Publisher: MDPI AG
Date: 12-01-2023
DOI: 10.3390/RS15020461
Abstract: A comparative study and evaluation of boundary layer height (BLH) estimation was conducted during an experimental c aign conducted at the Cape Grim Air Pollution station, Australia, from 1 June to 13 July 2019. The temporal and spatial distributions of BLH were studied using data from a ceilometer, sodar, in situ meteorological measurements, and back-trajectory analyses. Generally, the BLH under continental sources is lower than that under marine sources. The BLH is featured with a shallow depth of 515 ± 340 m under the Melbourne/East Victoria continental source. Especially the mixed continental sources (Melbourne/East Victoria and Tasmania direction) lead to a rise in radon concentration and lower BLH. In comparison, the boundary layer reaches a higher averaged BLH value of 730 ± 305 m when marine air is prevalent. The BLH derived from ERA5 is positively biased compared to the ceilometer observations, except when the boundary layer is stable. The height at which wind profiles experience rapid changes corresponds to the BLH value. The wind flow within the boundary layer increased up to ∼200 m, where it then meandered up to ∼300 m. Furthermore, the statistic shows that BLH is positively associated with near-surface wind speed. This study firstly provides information on boundary layer structure in Cape Grim and the interaction with wind, which may aid in further evaluating their associated impacts on the climate and ecosystem.
The molecular ecology of biological invasions: what do we know about non-additive genotypic effects and invasion success?
Publisher: Springer Science and Business Media LLC
Date: 11-10-2013
ACE-Asia intercomparison of a thermal-optical method for the determination of particle-phase organic and elemental carbon
Publisher: American Chemical Society (ACS)
Date: 23-01-2003
DOI: 10.1021/ES020622F
Abstract: A laboratory intercomparison of organic carbon (OC) and elemental carbon (EC) measurements of atmospheric particulate matter s les collected on quartz filters was conducted among eight participants of the ACE-Asia field experiment The intercomparison took place in two stages: the first round of the intercomparison was conducted when filter s les collected during the ACE-Asia experiment were being analyzed for OC and EC, and the second round was conducted after the ACE-Asia experiment and included selected s les from the ACE-Asia experiment Each participant operated ECOC analyzers from the same manufacturer and utilized the same analysis protocol for their measurements. The precision of OC measurements of quartz fiber filters was a function of the filter's carbon loading but was found to be in the range of 4-13% for OC loadings of 1.0-25 microg of C cm(-2). For measurements of EC, the precision was found to be in the range of 6-21% for EC loadings in the range of 0.7-8.4 microg of C cm(-2). It was demonstrated for three ambient s les, four source s les, and three complex mixtures of organic compounds that the relative amount of total evolved carbon allocated as OC and EC (i.e., the ECOC split) is sensitive to the temperature program used for analysis, and the magnitude of the sensitivity is dependent on the types of aerosol particles collected. The fraction of elemental carbon measured in wood smoke and an extract of organic compounds from a wood smoke s le were sensitive to the temperature program used for the ECOC analysis. The ECOC split for the three ambient s les and a coal fly ash s le showed moderate sensitivity to temperature program, while a carbon black s le and a s le of secondary organic aerosol were measured to have the same split of OC and EC with all temperature programs that were examined.
Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania, 41° S
Publisher: Copernicus GmbH
Date: 07-2015
DOI: 10.5194/ACPD-15-17599-2015
Abstract: Abstract. Biomass burning (BB) plumes were measured at the Cape Grim Baseline Air Pollution Station during the 2006 Precursors to Particles c aign, when emissions from a fire on nearby Robbins Island impacted the station. Measurements made included non methane organic compounds (NMOCs) (PTR-MS), particle number size distribution, condensation nuclei (CN) 3 nm, black carbon (BC) concentration, cloud condensation nuclei (CCN) number, ozone (O3), methane (CH4), carbon monixide (CO), hydrogen (H2), carbon dioxide (CO2), nitrous oxide (N2O), halocarbons and meteorology. During the first plume strike event (BB1), a four hour enhancement of CO (max ~ 2100 ppb), BC (~ 1400 ng m−3) and particles 3 nm (~ 13 000 cm−3) with dominant particle mode of 120 nm were observed overnight. Dilution of the plume resulted in a drop in the dominant particle mode to 50 nm, and then growth to 80 nm over 5 h. This was accompanied by an increase in O3, suggesting that photochemical processing of air and condensation of low volatility oxidation products may be driving particle growth. The ability of particles 80 nm (CN80) to act as CCN at 0.5 % supersaturation was investigated. The ΔCCN / ΔCN80 ratio was lowest during the fresh BB plume (56 %), higher during the particle growth event (77 %) and higher still (104 %) in background marine air. Particle size distributions indicate that changes to particle chemical composition, rather than particle size, are driving these changes. Hourly average CCN during both BB events were between 2000–5000 CCN cm−3, which were enhanced above typical background levels by a factor of 6–34, highlighting the dramatic impact BB plumes can have on CCN number in clean marine regions. During the 29 h of the second plume strike event (BB2) CO, BC and a range of NMOCs including acetonitrile and hydrogen cyanide (HCN) were clearly enhanced and some enhancements in O3 were observed (ΔO3 / ΔCO 0.001–0.074). A shortlived increase in NMOCs by a factor of 10 corresponded with a large CO enhancement, an increase of the NMOC / CO emission ratio (ER) by a factor of 2–4 and a halving of the BC / CO ratio. Rainfall on Robbins Island was observed by radar during this period which likely resulted in a lower fire combustion efficiency, and higher emission of compounds associated with smouldering. This highlights the importance of relatively minor meterological events on BB emissions. Emission factors (EF) were derived for a range of trace gases, some never before reported for Australian conditions, (including hydrogen, phenol and toluene) using a calculated ER to CO and a published CO EF. The EF derived for most species are comparable to other temperate Australian studies but lower than Northern Hemisphere temperate studies. This work demonstrates the substantial impact that BB plumes have on the composition of marine air, and the significant changes that can occur as the plume is diluted and interacts with other emission sources. We also provide new trace gas and particle EF for temperate southern Australia.
Flux chamber study of particle formation from Durvillaea potatorum
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/EN07006
Abstract: Environmental context. Kelp at Mace Head, Ireland, produces large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp (Durvillaea potatorum) but its role in particle formation appears limited. A flux chamber was used to better understand the response of Durvillaea potatorum to light stress and ozone. Abstract. Brown kelp, in particular Laminara digitata at Mace Head, Ireland, has been shown to emit iodine when under stress, resulting in new particle formation. The Cape Grim Baseline Air Pollution Station, Tasmania, is surrounded by rocky reefs that support large colonies of the brown kelp Durvillaea potatorum. During an intensive c aign in February 2006 at Cape Grim, levels of IO, OIO and methyl iodide remained at background levels and no particle formation events could be associated with locally generated precursor iodine species. In order to better understand the limitations of the local kelp to provide a source of precursor species, s les of Durvillaea potatorum were collected from the beach below the Cape Grim Station and tested for their capacity to initiate particle formation using a flux chamber technique. Particles were observed only when the kelp was exposed to both very high levels ( ppb) of ozone and natural solar radiation. There was a high correlation between ozone level and particles produced. The particles resulting from exposure to high levels of ozone were aromatic and volatile. Durvillaea potatorum appears to plays a very limited role in contributing to particle formation at Cape Grim, but it does represent a source of atmospheric iodine under photo-oxidative stress, of 18 pmol g–1 (fresh weight) min–1 and is likely to have a significant role in atmospheric chemistry at this site.
A Clean Air Plan for Sydney: An Overview of the Special Issue on Air Quality in New South Wales
Publisher: MDPI AG
Date: 04-12-2019
Abstract: This paper presents a summary of the key findings of the special issue of Atmosphere on Air Quality in New South Wales and discusses the implications of the work for policy makers and in iduals. This special edition presents new air quality research in Australia undertaken by (or in association with) the Clean Air and Urban Landscapes hub, which is funded by the National Environmental Science Program on behalf of the Australian Government’s Department of the Environment and Energy. Air pollution in Australian cities is generally low, with typical concentrations of key pollutants at much lower levels than experienced in comparable cities in many other parts of the world. Australian cities do experience occasional exceedances in ozone and PM2.5 (above air pollution guidelines), as well as extreme pollution events, often as a result of bushfires, dust storms, or heatwaves. Even in the absence of extreme events, natural emissions play a significant role in influencing the Australian urban environment, due to the remoteness from large regional anthropogenic emission sources. By studying air quality in Australia, we can gain a greater understanding of the underlying atmospheric chemistry and health risks in less polluted atmospheric environments, and the health benefits of continued reduction in air pollution. These conditions may be representative of future air quality scenarios for parts of the Northern Hemisphere, as legislation and cleaner technologies reduce anthropogenic air pollution in European, American, and Asian cities. However, in many instances, current legislation regarding emissions in Australia is significantly more lax than in other developed countries, making Australia vulnerable to worsening air pollution in association with future population growth. The need to avoid complacency is highlighted by recent epidemiological research, reporting associations between air pollution and adverse health outcomes even at air pollutant concentrations that are lower than Australia’s national air quality standards. Improving air quality is expected to improve health outcomes at any pollution level, with specific benefits projected for reductions in long-term exposure to average PM2.5 concentrations.
Characterization of aerosols over the Great Barrier Reef: The influence of transported continental sources
Publisher: Elsevier BV
Date: 11-2019
DOI: 10.1016/J.SCITOTENV.2019.07.007
Abstract: The rapid environmental changes in Australia prompt a more thorough investigation of the influence of transportation, local emissions, and optical-chemical properties on aerosol production across the region. A month-long intensive measurement c aign was conducted during spring 2016 at Mission Beach, a remote coastal site west of the Great Barrier Reef (GBR) on the north-east coast of Australia. One aerosol pollution episode was investigated in early October. This event was governed by meteorological conditions and characterized by the increase in black carbon (BC) mass concentration (averaged value of 0.35 ± 0.20 μg m
Are road verges corridors for weed invasion? Insights from the fine‐scale spatial genetic structure of R aphanus raphanistrum
Publisher: Wiley
Date: 21-06-2013
DOI: 10.1111/WRE.12033
Preface for Atmos. Env. Special issue on IBBI
Publisher: Elsevier BV
Date: 11-2015
Lower Hunter Particle Characterisation Study
Publisher: CSIRO
Date: 2016
Endotoxin health risk associated with high pressure cleaning using reclaimed water
Publisher: Elsevier BV
Date: 04-2017
Atmospheric reactive mercury concentrations in coastal Australia and the Southern Ocean
Publisher: Elsevier BV
Date: 2020
Risk in the mist? Deriving data to quantify microbial health risks associated with aerosol generation by water-efficient devices during typical domestic water-using activities
Publisher: IWA Publishing
Date: 12-2009
DOI: 10.2166/WST.2009.722
Abstract: The aim of this study was to address existing data gaps and to determine the size distribution of aerosols associated with water-efficient devices during typical domestic activities. This information is important to assist in understanding infection spread during water-using activities and in designing water regulations. Three water-using scenarios were evaluated: i) showering using a water-efficient showerhead ii) use of a high pressure spray unit for cleaning cars and iii) toilet flushing using a dual flush low volume flush device. For each scenario a control condition (conventional lower efficiency device) was selected for benchmarking purposes. Shower module results highlighted the complexity of particle generation and removal processes and showed that more than 90% of total particle mass in the breathing zone was attributed to particle diameters greater than 6 μm. Conversely, results for car washing experiments showed that particle diameters up to 6 μm constituted the major part of the total mass generated by both water-efficient and conventional devices. Even under worse case scenario conditions for toilet flushing, particle measurements were at or below the level of detection of the measuring instrumentation. The data provide information that assists in health risk assessment and in determining future research directions, including methodological aspects.
Air quality in Australia
Publisher: Springer Nature Singapore
Date: 2023
A global analysis of climate-relevant aerosol properties retrieved from the network of GAW near-surface observatories
Publisher: Copernicus GmbH
Date: 11-02-2020
DOI: 10.5194/AMT-2019-499
Abstract: Abstract. Aerosol particles are essential constituents of the Earth’s atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence time resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in-situ near-surface segment of the atmospheric observations system. This paper will provide the widest effort so far to document variability of climate-relevant in-situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High quality data from more than 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single scattering albedo and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information including data provision procedures, quality control and analysis, data policy and usage of the ground-based aerosol measurements network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully-characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.
Supplementary material to "Composition, size and cloud condensation nuclei activity of biomass burning aerosol from north Australian savannah fires"
Publisher: Copernicus GmbH
Date: 07-10-2016
Summer aerosol measurements over the East Antarctic seasonal ice zone
Publisher: Copernicus GmbH
Date: 26-11-2020
Abstract: Abstract. Aerosol measurements over the Southern Ocean have been identified as critical to an improved understanding of aerosol-radiation and aerosol-cloud interactions, as there currently exists significant discrepancies between model results and measurements in this region. Previous springtime measurements from the East Antarctic seasonal ice zone revealed a significant increase in aerosol number concentrations when crossing the atmospheric polar front into the Polar cell. A return voyage in summer 2017 made a more extensive range of aerosols measurements, including in particular aerosol number concentrations and submicron size distributions. Again, significantly greater aerosol number concentrations were observed in the Polar cell than in the Ferrel cell. Unlike the previous spring voyage however, the polar front was unable to be identified by a step change in aerosol concentration. A possible explanation is that atmospheric mixing across the polar front occurs to a greater degree in summer, therefore weakening the atmospheric boundary at the front. This atmospheric mixing in summer complicates the determination of the polar front location. These changes, together with the increased source of precursors from phytoplankton emissions, are likely to explain the seasonal differences observed in the magnitude of aerosol populations between the Ferrel and Polar cell. In the present analysis, meteorological variables were used to identify different air-masses and then aerosol measurements were compared based on these identifications. CN3 concentrations measured during wind directions indicative of Polar cell airmasses (median 594 cm−3) were larger than those measured during wind directions indicative of Ferrel cell air (median 265 cm−3). CN3 and CCN concentrations were larger during periods where the absolute humidity was less than 4.3 gH2O/m3, indicative of free tropospheric or Antarctic continental airmasses, compared to other periods of the voyage. These results indicate that a persistently more concentrated aerosol population is present in the Polar cell over the East Antarctic seasonal ice zone, although the observed difference between the two cells may vary seasonally.
Seasonality of the particle number concentration and size distribution: a global analysis retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
Publisher: Copernicus GmbH
Date: 25-11-2021
DOI: 10.5194/ACP-21-17185-2021
Abstract: Abstract. Aerosol particles are a complex component of the atmospheric system which influence climate directly by interacting with solar radiation, and indirectly by contributing to cloud formation. The variety of their sources, as well as the multiple transformations they may undergo during their transport (including wet and dry deposition), result in significant spatial and temporal variability of their properties. Documenting this variability is essential to provide a proper representation of aerosols and cloud condensation nuclei (CCN) in climate models. Using measurements conducted in 2016 or 2017 at 62 ground-based stations around the world, this study provides the most up-to-date picture of the spatial distribution of particle number concentration (Ntot) and number size distribution (PNSD, from 39 sites). A sensitivity study was first performed to assess the impact of data availability on Ntot's annual and seasonal statistics, as well as on the analysis of its diel cycle. Thresholds of 50 % and 60 % were set at the seasonal and annual scale, respectively, for the study of the corresponding statistics, and a slightly higher coverage (75 %) was required to document the diel cycle. Although some observations are common to a majority of sites, the variety of environments characterizing these stations made it possible to highlight contrasting findings, which, among other factors, seem to be significantly related to the level of anthropogenic influence. The concentrations measured at polar sites are the lowest (∼ 102 cm−3) and show a clear seasonality, which is also visible in the shape of the PNSD, while diel cycles are in general less evident, due notably to the absence of a regular day–night cycle in some seasons. In contrast, the concentrations characteristic of urban environments are the highest (∼ 103–104 cm−3) and do not show pronounced seasonal variations, whereas diel cycles tend to be very regular over the year at these stations. The remaining sites, including mountain and non-urban continental and coastal stations, do not exhibit as obvious common behaviour as polar and urban sites and display, on average, intermediate Ntot (∼ 102–103 cm−3). Particle concentrations measured at mountain sites, however, are generally lower compared to nearby lowland sites, and tend to exhibit somewhat more pronounced seasonal variations as a likely result of the strong impact of the atmospheric boundary layer (ABL) influence in connection with the topography of the sites. ABL dynamics also likely contribute to the diel cycle of Ntot observed at these stations. Based on available PNSD measurements, CCN-sized particles (considered here as either nm or nm) can represent from a few percent to almost all of Ntot, corresponding to seasonal medians on the order of ∼ 10 to 1000 cm−3, with seasonal patterns and a hierarchy of the site types broadly similar to those observed for Ntot. Overall, this work illustrates the importance of in situ measurements, in particular for the study of aerosol physical properties, and thus strongly supports the development of a broad global network of near surface observatories to increase and homogenize the spatial coverage of the measurements, and guarantee as well data availability and quality. The results of this study also provide a valuable, freely available and easy to use support for model comparison and validation, with the ultimate goal of contributing to improvement of the representation of aerosol–cloud interactions in models, and, therefore, of the evaluation of the impact of aerosol particles on climate.
Sources of Particulate Matter in the Hunter Valley, New South Wales, Australia
Publisher: MDPI AG
Date: 18-12-2019
Abstract: Exposure to particulate matter results in adverse health outcomes, especially in sensitive members of the community. Many communities that co-exist with industry are concerned about the perceived impact of emissions from that industry on their health. Such concerns have resulted in two studies in the Hunter Valley of New South Wales, Australia. The chemical composition of s les of particulate matter, collected over two 12-month s ling periods (2012 and 2014–2015) at six sites in the Hunter Valley and across two size fractions (PM2.5 and PM2.5–10) were input to a receptor model to determine the source of particulate matter influencing particle composition at the sites. Fourteen factors were found to contribute to particle mass. Of these, three source profiles common to all sites, size fractions, and s ling periods were sea salt, industry-aged sea salt and soil. Four source profiles were common across all sites for PM2.5 including secondary sulphate, secondary nitrate, mixed industry/vehicles, and woodsmoke. One source profile (other biomass smoke) was only identified in PM2.5 at Singleton and Muswellbrook, two source profiles (mixed industry/shipping and vehicles) were only identified in PM2.5 at Newcastle, Beresfield, Mayfield, and Stockton, and one source (primary nitrate) was only identified at Stockton in PM2.5. Three sources (bioaerosol, light absorbing particles (coal dust), and industry) were only identified in the PM2.5–10 size fraction at Mayfield and Stockton. The contribution of the soil factor to PM2.5 mass was consistent across the sites, while the fresh sea salt factor decreased with distance from the coast from 23% at Stockton to 3% at Muswellbrook, and smoke increased with distance from the coast. Primary industry was greatest at Stockton (due to the influence of ammonium nitrate emitted from a prilling tower) and lowest inland at Muswellbrook. In general, primary emissions across the sites accounted for 30% of the industry sources. The largest contribution to PM2.5 was from secondary sources at all sites except at Muswellbrook, where woodsmoke and industry sources each made an equal contribution of 40%. In general, secondary reactions accounted for approximately 70% of the industry source, although at Stockton, with the presence of the prilling tower, this split was 50% primary and 50% secondary and at Muswellbrook, the split was 20% primary and 80% secondary. These findings add to the evidence base required to inform policies and programs that will improve air quality in the Hunter Valley.
Suitability of high-volume aerosol samplers for ultra-trace aerosol iron measurements in pristine air masses: blanks, recoveries and bugs
Publisher: Copernicus GmbH
Date: 08-04-2016
DOI: 10.5194/AMT-2016-12
Abstract: Abstract. Atmospheric inputs of soluble iron (Fe) to the global ocean are an important factor determining marine primary productivity and nitrogen fixation. To investigate soluble aerosol Fe and fractional Fe solubility, marine aerosol s ling has been conducted from a number of platforms including aerosol towers, ship and buoy platforms. A number of these studies have used commercially available high-volume aerosol s lers to collect aerosols from large volumes of air. These s lers are attractive for s ling air from low Fe air masses since they can rapidly concentrate large volumes improving detection limits. Here we investigate the use of a high-volume s ler from the Cape Grim Baseline Air Pollution Station (CGBAPS), Tasmania, Australia to s le aerosol Fe from baseline Southern Ocean air-masses. The study followed the United States Environmental Protection Agency (EPA) standard for the s ling of ambient air using high-volume s ler, and the recommendations and protocols from GEOTRACES community for s ling, s le preparation and digestion of trace element aerosols. Analysis and inspection of exposure blank (one month exposure) filters for Fe, and other metals, revealed significant contamination resulting from passive deposition of local soil, plants and insects. The results of the study suggest that high-volume aerosol s lers may not be suitable for low concentration air masses over the Southern Ocean without some mechanism to hermetically seal the s ler when the baseline s ling criteria are not met.
Comprehensive aerosol and gas data set from the Sydney Particle Study
Publisher: Copernicus GmbH
Date: 13-05-2019
DOI: 10.5194/ESSD-2019-56
Abstract: Abstract. The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February/March 2011 and April/May 2012. The aim of this study was to increase scientific knowledge of the processes leading to particle formation and transformations in Sydney. In this paper we describe the methods used to collect and analyse particle and gaseous s les, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties and gaseous concentrations. This paper also provides a description of the data collected and is a meta data record for the data sets published in Keywood et al. (2016a) 0.4225/08/57903B83D6A5D and Keywood et al. (2016b) 0.4225/08/5791B5528BD63.
Supplementary material to "Seasonality of the particle number concentration and size distribution: a global analysis retrieved from the network of Global Atmosphere Watch (GAW) near-surface o
Publisher: Copernicus GmbH
Date: 07-01-2021
Identification of platform exhaust on the RV Investigator
Publisher: Copernicus GmbH
Date: 17-09-2018
DOI: 10.5194/AMT-2018-214
Abstract: Abstract. Ship-based measurements are an important component in developing an understanding of the global atmosphere. A common problem that impacts the quality of atmospheric data collected from marine research vessels is exhaust from both diesel combustion and waste incineration from the ship itself. Described here is an algorithm, developed for the recently commissioned Australian blue-water Research Vessel (RV) Investigator, that identifies exhaust periods in s led air. The RV Investigator, with two dedicated atmospheric laboratories, represents an unprecedented opportunity for high quality measurements of the marine atmosphere. The algorithm avoids using ancillary data such as wind speed and direction, and instead utilises components of the exhaust itself – aerosol number concentration, black carbon concentration, and carbon monoxide and carbon dioxide mixing ratios. The exhaust signal is identified within each of these parameters in idually before they are combined and an additional window filter is applied. The algorithm relies heavily on statistical methods, rather than setting thresholds that are too rigid to accommodate potential temporal changes. The algorithm is more effective than traditional wind-based filters in removing exhaust data without removing exhaust-free data which commonly occurs with traditional filters. With suitable testing, the algorithm has the potential to be applied to other ship-based atmospheric measurements where suitable measurements exist.
Dry season aerosol iron solubility in tropical northern Australia
Publisher: Copernicus GmbH
Date: 14-10-2016
DOI: 10.5194/ACP-16-12829-2016
Abstract: Abstract. Marine nitrogen fixation is co-limited by the supply of iron (Fe) and phosphorus in large regions of the global ocean. The deposition of soluble aerosol Fe can initiate nitrogen fixation and trigger toxic algal blooms in nitrate-poor tropical waters. We present dry season soluble Fe data from the Savannah Fires in the Early Dry Season (SAFIRED) c aign in northern Australia that reflects coincident dust and biomass burning sources of soluble aerosol Fe. The mean soluble and total aerosol Fe concentrations were 40 and 500 ng m−3 respectively. Our results show that while biomass burning species may not be a direct source of soluble Fe, biomass burning may substantially enhance the solubility of mineral dust. We observed fractional Fe solubility up to 12 % in mixed aerosols. Thus, Fe in dust may be more soluble in the tropics compared to higher latitudes due to higher concentrations of biomass-burning-derived reactive organic species in the atmosphere. In addition, biomass-burning-derived particles can act as a surface for aerosol Fe to bind during atmospheric transport and subsequently be released to the ocean upon deposition. As the aerosol loading is dominated by biomass burning emissions over the tropical waters in the dry season, additions of biomass-burning-derived soluble Fe could have harmful consequences for initiating nitrogen-fixing toxic algal blooms. Future research is required to quantify biomass-burning-derived particle sources of soluble Fe over tropical waters.
Indoor air quality in typical temperate zone Australian dwellings
Publisher: Elsevier BV
Date: 07-2012
Skill-Testing Chemical Transport Models across Contrasting Atmospheric Mixing States Using Radon-222
Publisher: MDPI AG
Date: 28-11-2018
DOI: 10.20944/PREPRINTS201811.0607.V1
Abstract: We propose a new technique to prepare statistically-robust benchmarking data for evaluating chemical transport model meteorology and air quality parameters within the urban boundary layer. The approach employs atmospheric class-typing, using nocturnal radon measurements to assign atmospheric mixing classes, and can be applied temporally (across the diurnal cycle), or spatially (to create angular distributions of pollutants as a top-down constraint on emissions inventories). In this study only a short (& -month) c aign is used, but grouping of the relative mixing classes based on nocturnal mean radon concentrations can be adjusted according to dataset length (i.e., number of days per category), or desired range of within-class variability. Calculating hourly distributions of observed and simulated values across diurnal composites of each class-type helps to: (i) bridge the gap between scales of simulation and observation, (ii) represent the variability associated with spatial and temporal heterogeneity of sources and meteorology without being confused by it, and (iii) provide an objective way to group results over whole diurnal cycles that separates & lsquo natural complicating factors& rsquo (synoptic non-stationarity, rainfall, mesoscale motions, extreme stability, etc.) from problems related to parameterizations, or between-model differences. We demonstrate the utility of this technique using output from a suite of seven contemporary regional forecast and chemical transport models. Meteorological model skill varied across the diurnal cycle for all models, with an additional dependence on the atmospheric mixing class that varied between models. From an air quality perspective, model skill regarding the duration and magnitude of morning and evening & rush hour& pollution events varied strongly as a function of mixing class. Model skill was typically the lowest when public exposure would have been the highest, which has important implications for assessing potential health risks in new and rapidly evolving urban regions, and also for prioritizing the areas of model improvement for future applications.
Cloud condensation nuclei over the Southern Ocean: wind dependence and seasonal cycles
Publisher: Copernicus GmbH
Date: 03-04-2017
Abstract: Abstract. Multi-decadal observations of aerosol microphysical properties from regionally representative sites can be used to challenge regional or global numerical models that simulate atmospheric aerosol. Presented here is an analysis of multi-decadal observations at Cape Grim (Australia) that characterise production and removal of the background marine aerosol in the Southern Ocean marine boundary layer (MBL) on both short-term weather-related and underlying seasonal scales.A trimodal aerosol distribution comprises Aitken nuclei ( 100 nm), cloud condensation nuclei (CCN)/accumulation (100–350 nm) and coarse-particle ( 350 nm) modes, with the Aitken mode dominating number concentration. Whilst the integrated particle number in the MBL over the clean Southern Ocean is only weakly dependent on wind speed, the different modes in the aerosol size distribution vary in their relationship with wind speed. The balance between a positive wind dependence in the coarse mode and negative dependence in the accumulation/CCN mode leads to a relatively flat wind dependence in summer and moderately strong positive wind dependence in winter. The changeover in wind dependence of these two modes occurs in a very small size range at the mode intersection, indicative of differences in the balance of production and removal in the coarse and accumulation/CCN modes.Whilst a marine biological source of reduced sulfur appears to dominate CCN concentration over the summer months (December to February), other components contribute to CCN over the full annual cycle. Wind-generated coarse-mode sea salt is an important CCN component year round and is the second-most-important contributor to CCN from autumn through to mid-spring (March to November). A portion of the non-seasonally dependent contributor to CCN can clearly be attributed to wind-generated sea salt, with the remaining part potentially being attributed to long-range-transported material. Under conditions of greater supersaturation, as expected in more convective cyclonic systems and their associated fronts, Aitken mode particles become increasingly important as CCN.
Comparison of mercury concentrations measured at several sites in the Southern Hemisphere
Publisher: Copernicus GmbH
Date: 19-03-2015
Abstract: Abstract. Our knowledge of the distribution of mercury concentrations in air of the Southern Hemisphere was until recently based mostly on intermittent measurements made during ship cruises. In the last few years continuous mercury monitoring has commenced at several sites in the Southern Hemisphere, providing new and more refined information. In this paper we compare mercury measurements at several remote sites in the Southern Hemisphere made over a period of at least 1 year at each location. Averages of monthly medians show similar although small seasonal variations at both Cape Point and Amsterdam Island. A pronounced seasonal variation at Troll research station in Antarctica is due to frequent mercury depletion events in the austral spring. Due to large scatter and large standard deviations of monthly average median mercury concentrations at Cape Grim, no systematic seasonal variation could be found there. Nevertheless, the annual average mercury concentrations at all sites during the 2007–2013 period varied only between 0.85 and 1.05 ng m−3. Part of this variability is likely due to systematic measurement uncertainties which we propose can be further reduced by improved calibration procedures. We conclude that mercury is much more uniformly distributed throughout the Southern Hemisphere than the distributions suggested by measurements made onboard ships. This finding implies that smaller trends can be detected in shorter time periods. We also report a change in the trend sign at Cape Point from decreasing mercury concentrations in 1996–2004 to increasing concentrations since 2007.
Supplementary material to "A global analysis of climate-relevant aerosol properties retrieved from the network of GAW near-surface observatories"
Publisher: Copernicus GmbH
Date: 11-02-2020
Identification of platform exhaust on the RV <i>Investigator</i>
Publisher: Copernicus GmbH
Date: 04-06-2019
Abstract: Abstract. Oceans cover over 70 % of the Earth's surface. Ship-based measurements are an important component in developing an understanding of atmosphere of this vast region. A common problem that impacts the quality of atmospheric data collected from marine research vessels is exhaust from both diesel combustion and waste incineration from the ship itself. Described here is an algorithm, developed for the recently commissioned Australian blue-water research vessel (RV) Investigator, that identifies exhaust periods in s led air. The RV Investigator, with two dedicated atmospheric laboratories, represents an unprecedented opportunity for high-quality measurements of the marine atmosphere. The algorithm avoids using ancillary data such as wind speed and direction, and instead utilises components of the exhaust itself – aerosol number concentration, black carbon concentration, and carbon monoxide and carbon dioxide mixing ratios. The exhaust signal is identified within each of these parameters in idually before they are combined and an additional window filter is applied. The algorithm relies heavily on statistical methods, rather than setting thresholds that are too rigid to accommodate potential temporal changes. The algorithm is more effective than traditional wind-based filters in removing exhaust data without removing exhaust-free data, which commonly occurs with traditional filters. In application to the current dataset, the algorithm identifies 26 % of the wind filter's “clean” data as exhaust, and recovers 5 % of data falsely removed by the wind filter. With suitable testing, the algorithm has the potential to be applied to other ship-based atmospheric measurements where suitable measurements exist.
Pearl millet genome sequence provides a resource to improve agronomic traits in arid environments
Publisher: Springer Science and Business Media LLC
Date: 18-09-2017
DOI: 10.1038/NBT.3943
Abstract: Pearl millet [ Cenchrus americanus (L.) Morrone] is a staple food for more than 90 million farmers in arid and semi-arid regions of sub-Saharan Africa, India and South Asia. We report the ∼1.79 Gb draft whole genome sequence of reference genotype Tift 23D 2 B 1 -P1-P5, which contains an estimated 38,579 genes. We highlight the substantial enrichment for wax biosynthesis genes, which may contribute to heat and drought tolerance in this crop. We resequenced and analyzed 994 pearl millet lines, enabling insights into population structure, genetic ersity and domestication. We use these resequencing data to establish marker trait associations for genomic selection, to define heterotic pools, and to predict hybrid performance. We believe that these resources should empower researchers and breeders to improve this important staple crop.
Fallout of chlorine 36 to the Earth's surface in the southern hemisphere
Publisher: American Geophysical Union (AGU)
Date: 04-1998
DOI: 10.1029/97JD03125
Boundary layer new particle formation over East Antarctic sea ice – possible Hg driven nucleation?
Publisher: Copernicus GmbH
Date: 16-07-2015
DOI: 10.5194/ACPD-15-19477-2015
Abstract: Abstract. Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on-board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air-mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3) reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with Total Gaseous Mercury (TGM) were found that, together with other data, suggest a mercury driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (~ 1.5 ng m−3 and & geq 600 W m−2, respectively), such as those observed in the Antarctic sea ice boundary layer in this study or in the global free-troposphere, particularly in the Northern Hemisphere.
The contribution of coral reef-derived dimethyl sulfide to aerosol burden over the Great Barrier Reef: a modelling study
Publisher: Copernicus GmbH
Date: 29-07-2021
DOI: 10.5194/ACP-2021-507
Abstract: Abstract. Coral reefs have been found to produce the sulfur compound dimethyl sulfide (DMS), a climatically relevant aerosol precursor predominantly associated with phytoplankton. Until recently, the role of coral reef-derived DMS within the climate system had not been quantified. A study preceding the present work found that DMS produced by corals had negligible long-term climatic forcing at the global-regional scale. However, at sub-daily time scales more typically associated with aerosol and cloud formation, the influence of coral reef-derived DMS on local aerosol radiative effects remains unquantified. The Weather Research and Forecasting – chemistry model (WRF-Chem) has been used in this work to study the role of coral reef-derived DMS at sub-daily time scales for the first time. WRF-Chem was run to coincide with an October 2016 field c aign over the Great Barrier Reef, Queensland, Australia, against which the model was evaluated. After updating the DMS surface water climatology, the model reproduced DMS and sulfur concentrations well. The inclusion of coral reef-derived DMS resulted in no significant change in sulfate aerosol mass or total aerosol number. Subsequently, no direct or indirect aerosol effects were detected. The results suggest that the co-location of the Great Barrier Reef with significant anthropogenic aerosol sources along the Queensland coast prevents coral reef derived-aerosol from having a modulating influence on local aerosol burdens in the current climate.
An evaluation of PM10 and PM2.5 size selective inlet performance using ambient aerosol
Publisher: Informa UK Limited
Date: 04-1999
Measurements of Secondary Organic Aerosol from Oxidation of Cycloalkenes, Terpenes, and m-Xylene Using an Aerodyne Aerosol Mass Spectrometer
Publisher: American Chemical Society (ACS)
Date: 30-06-2005
DOI: 10.1021/ES048061A
Abstract: The Aerodyne aerosol mass spectrometer (AMS) was used to characterize physical and chemical properties of secondary organic aerosol (SOA) formed during ozonolysis of cycloalkenes and biogenic hydrocarbons and photo-oxidation of m-xylene. Comparison of mass and volume distributions from the AMS and differential mobility analyzers yielded estimates of "effective" density of the SOA in the range of 0.64-1.45 g/cm3, depending on the particular system. Increased contribution of the fragment at m/z 44, C02+ ion fragment of oxygenated organics, and higher "delta" values, based on ion series analysis of the mass spectra, in nucleation experiments of cycloalkenes suggest greater contribution of more oxygenated molecules to the SOA as compared to those formed under seeded experiments. Dominant negative "delta" values of SOA formed during ozonolysis of biogenics indicates the presence of terpene derivative structures or cyclic or unsaturated oxygenated compounds in the SOA. Evidence of acid-catalyzed heterogeneous chemistry, characterized by greater contribution of higher molecular weight fragments to the SOA and corresponding changes in "delta" patterns, is observed in the ozonolysis of alpha-pinene. Mass spectra of SOA formed during photooxidation of m-xylene exhibit features consistent with the presence of furandione compounds and nitro organics. This study demonstrates that mixtures of SOA compounds produced from similar precursors result in broadly similar AMS mass spectra. Thus, fragmentation patterns observed for biogenic versus anthropogenic SOA may be useful in determining the sources of ambient SOA.
Determination of nicotine in water by gradient ion chromatography
Publisher: Elsevier BV
Date: 10-1998
DOI: 10.1016/S0021-9673(98)00632-3
Abstract: A sensitive gradient ion chromatographic method has been demonstrated for determination of nicotine in aqueous solution. The method provides an improvement in detection limit, plus a reduction in analysis time, compared with a previously published ion chromatographic method.
Chemical Characterization of Isoprene- and Monoterpene-Derived Secondary Organic Aerosol Tracers in Remote Marine Aerosols over a Quarter Century
Publisher: American Chemical Society (ACS)
Date: 29-04-2019
Supplementary material to "Multidecadal trend analysis of aerosol radiative properties at a global scale"
Publisher: Copernicus GmbH
Date: 14-01-2020
Factors controlling winter-time aerosol light scattering in Launceston, Tasmania
Publisher: Elsevier BV
Date: 04-2001
Marine productivity and synoptic meteorology drive summer-time variability in Southern Ocean aerosols
Publisher: Copernicus GmbH
Date: 10-07-2020
Abstract: Abstract. Cloud–radiation interactions over the Southern Ocean are not well constrained in climate models, in part due to uncertainties in the sources, concentrations, and cloud-forming potential of aerosol in this region. To date, most studies in this region have reported measurements from fixed terrestrial stations or a limited set of instrumentation and often present findings as broad seasonal or latitudinal trends. Here, we present an extensive set of aerosol and meteorological observations obtained during an austral summer cruise across the full width of the Southern Ocean south of Australia. Three episodes of continental-influenced air masses were identified, including an apparent transition between the Ferrel atmospheric cell and the polar cell at approximately 64∘ S, and accompanied by the highest median cloud condensation nuclei (CCN) concentrations, at 252 cm−3. During the other two episodes, synoptic-scale weather patterns erted air masses across distances greater than 1000 km from the Australian and Antarctic coastlines, respectively, indicating that a large proportion of the Southern Ocean may be periodically influenced by continental air masses. In all three cases, a highly cloud-active accumulation mode dominated the size distribution, with up to 93 % of the total number concentration activating as CCN. Frequent cyclonic weather conditions were observed at high latitudes and the associated strong wind speeds led to predictions of high concentrations of sea spray aerosol. However, these modelled concentrations were not achieved due to increased aerosol scavenging rates from precipitation and convective transport into the free troposphere, which decoupled the air mass from the sea spray flux at the ocean surface. CCN concentrations were more strongly impacted by high concentrations of large-diameter Aitken mode aerosol in air masses which passed over regions of elevated marine biological productivity, potentially contributing up to 56 % of the cloud condensation nuclei concentration. Weather systems were vital for aerosol growth in biologically influenced air masses and in their absence ultrafine aerosol diameters were less than 30 nm. These results demonstrate that air mass meteorological history must be considered when modelling sea spray concentrations and highlight the potential importance of sub-grid-scale variability when modelling atmospheric conditions in the remote Southern Ocean.
A western Sahara centre of domestication inferred from pearl millet genomes
Publisher: Springer Science and Business Media LLC
Date: 06-08-2018
DOI: 10.1038/S41559-018-0643-Y
Abstract: There have been intense debates over the geographic origin of African crops and agriculture. Here, we used whole-genome sequencing data to infer the domestication origin of pearl millet (Cenchrus americanus). Our results supported an origin in western Sahara, and we dated the onset of cultivated pearl millet expansion in Africa to 4,900 years ago. We provided evidence that wild-to-crop gene flow increased cultivated genetic ersity leading to ersity hotspots in western and eastern Sahel and adaptive introgression of 15 genomic regions. Our study reconciled genetic and archaeological data for one of the oldest African crops.
Southern Ocean latitudinal gradients of cloud condensation nuclei
Publisher: Copernicus GmbH
Date: 30-08-2021
DOI: 10.5194/ACP-21-12757-2021
Abstract: Abstract. The Southern Ocean region is one of the most pristine in the world and serves as an important proxy for the pre-industrial atmosphere. Improving our understanding of the natural processes in this region is likely to result in the largest reductions in the uncertainty of climate and earth system models. While remoteness from anthropogenic and continental sources is responsible for its clean atmosphere, this also results in the dearth of atmospheric observations in the region. Here we present a statistical summary of the latitudinal gradient of aerosol (condensation nuclei larger than 10 nm, CN10) and cloud condensation nuclei (CCN at various supersaturations) concentrations obtained from five voyages spanning the Southern Ocean between Australia and Antarctica from late spring to early autumn (October to March) of the 2017/18 austral seasons. Three main regions of influence were identified: the northern sector (40–45∘ S), where continental and anthropogenic sources coexisted with background marine aerosol populations the mid-latitude sector (45–65∘ S), where the aerosol populations reflected a mixture of biogenic and sea-salt aerosol and the southern sector (65–70∘ S), south of the atmospheric polar front, where sea-salt aerosol concentrations were greatly reduced and aerosol populations were primarily biologically derived sulfur species with a significant history in the Antarctic free troposphere. The northern sector showed the highest number concentrations with median (25th to 75th percentiles) CN10 and CCN0.5 concentrations of 681 (388–839) cm−3 and 322 (105–443) cm−3, respectively. Concentrations in the mid-latitudes were typically around 350 cm−3 and 160 cm−3 for CN10 and CCN0.5, respectively. In the southern sector, concentrations rose markedly, reaching 447 (298–446) cm−3 and 232 (186–271) cm−3 for CN10 and CCN0.5, respectively. The aerosol composition in this sector was marked by a distinct drop in sea salt and increase in both sulfate fraction and absolute concentrations, resulting in a substantially higher CCN0.5/CN10 activation ratio of 0.8 compared to around 0.4 for mid-latitudes. Long-term measurements at land-based research stations surrounding the Southern Ocean were found to be good representations at their respective latitudes however this study highlighted the need for more long-term measurements in the region. CCN observations at Cape Grim (40∘39′ S) corresponded with CCN measurements from northern and mid-latitude sectors, while CN10 observations only corresponded with observations from the northern sector. Measurements from a simultaneous 2-year c aign at Macquarie Island (54∘30′ S) were found to represent all aerosol species well. The southernmost latitudes differed significantly from both of these stations, and previous work suggests that Antarctic stations on the East Antarctic coastline do not represent the East Antarctic sea-ice latitudes well. Further measurements are needed to capture the long-term, seasonal and longitudinal variability in aerosol processes across the Southern Ocean.
Skill-Testing Chemical Transport Models across Contrasting Atmospheric Mixing States Using Radon-222
Publisher: MDPI AG
Date: 11-01-2019
Abstract: We propose a new technique to prepare statistically-robust benchmarking data for evaluating chemical transport model meteorology and air quality parameters within the urban boundary layer. The approach employs atmospheric class-typing, using nocturnal radon measurements to assign atmospheric mixing classes, and can be applied temporally (across the diurnal cycle), or spatially (to create angular distributions of pollutants as a top-down constraint on emissions inventories). In this study only a short ( -month) c aign is used, but grouping of the relative mixing classes based on nocturnal mean radon concentrations can be adjusted according to dataset length (i.e., number of days per category), or desired range of within-class variability. Calculating hourly distributions of observed and simulated values across diurnal composites of each class-type helps to: (i) bridge the gap between scales of simulation and observation, (ii) represent the variability associated with spatial and temporal heterogeneity of sources and meteorology without being confused by it, and (iii) provide an objective way to group results over whole diurnal cycles that separates ‘natural complicating factors’ (synoptic non-stationarity, rainfall, mesoscale motions, extreme stability, etc.) from problems related to parameterizations, or between-model differences. We demonstrate the utility of this technique using output from a suite of seven contemporary regional forecast and chemical transport models. Meteorological model skill varied across the diurnal cycle for all models, with an additional dependence on the atmospheric mixing class that varied between models. From an air quality perspective, model skill regarding the duration and magnitude of morning and evening “rush hour” pollution events varied strongly as a function of mixing class. Model skill was typically the lowest when public exposure would have been the highest, which has important implications for assessing potential health risks in new and rapidly evolving urban regions, and also for prioritizing the areas of model improvement for future applications.
Comparison of mercury concentrations measured at several sites in the Southern Hemisphere
Publisher: Copernicus GmbH
Date: 03-12-2014
DOI: 10.5194/ACPD-14-30611-2014
Abstract: Abstract. Our knowledge of the distribution of mercury concentrations in air of the Southern Hemisphere was until recently based mostly on intermittent measurements made during ship cruises. In the last few years continuous mercury monitoring has commenced at several sites in the Southern Hemisphere providing new and more refined information. In this paper we compare mercury measurements at several sites in the Southern Hemisphere made over a period of at least one year at each location. Averages of monthly medians show similar although small seasonal variations at both Cape Point and Amsterdam Island. A pronounced seasonal variation at Troll Research Station in Antarctica is due to frequent mercury depletion events in the austral spring. Due to large scatter and large standard deviations of monthly average median mercury concentrations at Cape Grim no systematic seasonal variation could be found there. Nevertheless, the annual average mercury concentrations at all sites during the 2007–2013 period varied only between 0.85 and 1.05 ng m−3. Part of this variability is likely due to systematic measurement uncertainties which we propose can be further reduced by improved calibration procedures. We conclude that mercury is much more uniformly distributed throughout the Southern Hemisphere than the distributions suggested by measurements made onboard ships. This finding implies (a) that trends observed at one or a few sites in the Southern Hemisphere are likely to be representative for the whole hemisphere, and (b) that smaller trends can be detected in shorter time periods. We also report a change of the trend sign at Cape Point from decreasing mercury concentrations in 1996–2004 to increasing concentrations since 2007.
Upper Hunter Valley Particle Characterization Study
Publisher: CSIRO
Date: 2013
A global analysis of climate-relevant aerosol properties retrieved from the network of GAW near-surface observatories
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-2147
Abstract: & & Aerosol particles are essential constituents of the Earth& #8217 s atmosphere, impacting the earth radiation balance directly by scattering and absorbing solar radiation, and indirectly by acting as cloud condensation nuclei. In contrast to most greenhouse gases, aerosol particles have short atmospheric residence time resulting in a highly heterogeneous distribution in space and time. There is a clear need to document this variability at regional scale through observations involving, in particular, the in-situ near-surface segment of the atmospheric observations system. This paper will provide the widest effort so far to document variability of climate-relevant in-situ aerosol properties (namely wavelength dependent particle light scattering and absorption coefficients, particle number concentration and particle number size distribution) from all sites connected to the Global Atmosphere Watch network. High quality data from more than 90 stations worldwide have been collected and controlled for quality and are reported for a reference year in 2017, providing a very extended and robust view of the variability of these variables worldwide. The range of variability observed worldwide for light scattering and absorption coefficients, single scattering albedo and particle number concentration are presented together with preliminary information on their long-term trends and comparison with model simulation for the different stations. The scope of the present paper is also to provide the necessary suite of information including data provision procedures, quality control and analysis, data policy and usage of the ground-based aerosol measurements network. It delivers to users of the World Data Centre on Aerosol, the required confidence in data products in the form of a fully-characterized value chain, including uncertainty estimation and requirements for contributing to the global climate monitoring system.& &
Observations of Clouds, Aerosols, Precipitation, and Surface Radiation over the Southern Ocean: An Overview of CAPRICORN, MARCUS, MICRE, and SOCRATES
Publisher: American Meteorological Society
Date: 04-2021
Abstract: Weather and climate models are challenged by uncertainties and biases in simulating Southern Ocean (SO) radiative fluxes that trace to a poor understanding of cloud, aerosol, precipitation, and radiative processes, and their interactions. Projects between 2016 and 2018 used in situ probes, radar, lidar, and other instruments to make comprehensive measurements of thermodynamics, surface radiation, cloud, precipitation, aerosol, cloud condensation nuclei (CCN), and ice nucleating particles over the SO cold waters, and in ubiquitous liquid and mixed-phase clouds common to this pristine environment. Data including soundings were collected from the NSF–NCAR G-V aircraft flying north–south gradients south of Tasmania, at Macquarie Island, and on the R/V Investigator and RSV Aurora Australis . Synergistically these data characterize boundary layer and free troposphere environmental properties, and represent the most comprehensive data of this type available south of the oceanic polar front, in the cold sector of SO cyclones, and across seasons. Results show largely pristine environments with numerous small and few large aerosols above cloud, suggesting new particle formation and limited long-range transport from continents, high variability in CCN and cloud droplet concentrations, and ubiquitous supercooled water in thin, multilayered clouds, often with small-scale generating cells near cloud top. These observations demonstrate how cloud properties depend on aerosols while highlighting the importance of dynamics and turbulence that likely drive heterogeneity of cloud phase. Satellite retrievals confirmed low clouds were responsible for radiation biases. The combination of models and observations is examining how aerosols and meteorology couple to control SO water and energy budgets.
Biomass burning at Cape Grim: exploring photochemistry using multi-scale modelling
Publisher: Copernicus GmbH
Date: 05-12-2016
DOI: 10.5194/ACP-2016-932
Abstract: Abstract. We have tested the ability of high resolution chemical transport modelling (CTM) to reproduce biomass burning (BB) plume strikes observed at Cape Grim in Tasmania Australia from the Robbins Island fire. The model has also been used to explore the contribution of near-field BB emissions and background sources to ozone (O3) under conditions of complex meteorology. Using atmospheric observations, we have tested model sensitivity to meteorology, BB emission factors (EF) corresponding to low, medium and high modified combustion efficiency (MCE) and spatial variability. The use of two different meteorological models varied the first (BB1) plume strike time by up to 15 hours, and duration of impact between 12 and 36 hours, while the second plume strike (BB2) was simulated well using both meteorological models. Meteorology also had a large impact on simulated O3, with one model (TAPM-CTM) simulating 4 periods of O3 enhancement, while the other model (CCAM) simulating only one period. Varying the BB EFs which in turn varied the non methanic-organic compound (NMOC) / oxides of nitrogen (NOx) ratio had a strongly non-linear impact on O3 concentration, with either destruction or production of O3 predicted in different simulations. As shown in the previous work (Lawson et al., 2015), minor rainfall events have the potential to significantly alter EF due to changes in combustion processes. Models which assume fixed EF for O3 precursor species in an environment with temporally or spatially variable EF may be unable to simulate the behaviour of important species such as O3. TAPM-CTM is used to explore the contribution of the Robbins Island fire to the observed O3 enhancements during BB1 and BB2. Overall, the model suggests the dominant source of O3 observed at Cape Grim was aged urban air (age = 2 days), with a contribution of O3 formed from local BB emissions. The model indicates that in an area surrounding Cape Grim, between 25–43 % of O3 enhancement during BB1 was formed from BB emissions while the fire led to a net depletion in O3 during BB2. This work shows the importance of assessing model sensitivity to meteorology and EF, and the large impact these variables can have in particular on simulated destruction or production of O3. This work also demonstrates how a model can be used to elucidate the degree of contribution from different sources to atmospheric composition, where this is difficult using observations alone.
Fractional iron solubility of atmospheric iron inputs to the Southern Ocean
Publisher: Elsevier BV
Date: 12-2015
Seasonality of the particle number concentration and size distribution: a global analysis retrieved from the network of Global Atmosphere Watch (GAW) near-surface observatories
Publisher: Copernicus GmbH
Date: 07-01-2021
Abstract: Abstract. Aerosol particles are a complex component of the atmospheric system that influences climate directly by interacting with solar radiation, and indirectly by contributing to cloud formation. The variety of their sources, as well as the multiple transformations they may undergo during their transport, result in significant spatial and temporal variability of their properties. Documenting this variability is essential to provide a proper representation of aerosols and cloud condensation nuclei (CCN) in climate models. Using measurements conducted in 2016 or 2017 at 62 ground based stations around the world, this study provides the most up-to-date picture of the spatial distribution of particle number concentration (Ntot) and number size distribution (PNSD, from 39 sites). A sensitivity study was first performed to assess the impact of data availability on Ntot's annual and seasonal statistics, as well as on the analysis of its diel cycle. Thresholds of 50 % and 60 % were set at the seasonal and annual scale, respectively, for the study of the corresponding statistics, and a slightly higher coverage (75 %) was required to document the diel cycle. Although some observations are common to a majority of sites, the variety of environments characterizing these stations made it possible to highlight contrasting findings, which, among other factors, seem to be significantly related to the level of anthropogenic influence. The concentrations measured at polar sites are the lowest (~102 cm−3) and show a clear seasonality, which is also visible in the shape of the PNSD, while diel cycles are in general barely marked, due notably to the absence of a regular day-night cycle in some seasons. In contrast, the concentrations characteristic of urban environments are the highest (~103–104 cm−3) and do not show pronounced seasonal variations, whereas diel cycles tend to be very regular over the year at these stations. The remaining sites, including mountain and non-urban continental and coastal stations, do not exhibit as obvious common behaviour as polar and urban sites and display, on average, intermediate Ntot (~102–103 cm−3). Particle concentrations measured at mountain sites, however, are generally lower compared to nearby lowland sites, and tend to exhibit somewhat more pronounced seasonal variations as a likely result of the strong impact of the atmospheric boundary layer (ABL) influence in connection with the topography of the sites. ABL dynamics also likely contribute to the diel cycle of Ntot observed at these stations. Based on available PNSD measurements, CCN-sized particles (i.e. 50–100 nm) can represent from a few percent to almost all of Ntot, corresponding to seasonal medians in the order of ~10 to 1000 cm−3, with seasonal patterns and a hierarchy of the site types broadly similar to those observed for Ntot. Overall, this work illustrates the importance of in-situ measurements, in particular for the study of aerosol physical properties, and thus strongly supports the development of a broad global network of near surface observatories to increase and homogenize the spatial coverage of the measurements, and guarantee as well data availability and quality. The results of this study also provide a valuable, freely available and easy to use support for model comparison and validation, with the ultimate goal of contributing to improvement of the representation of aerosol-cloud interactions in models, and, therefore, of the evaluation of the impact of aerosol particles on climate.
Dry season aerosol iron solubility in tropical northern Australia
Publisher: Copernicus GmbH
Date: 17-06-2016
DOI: 10.5194/ACP-2016-419
Abstract: Abstract. Marine nitrogen fixation is co-limited by the supply of iron and phosphorus in large areas of the global ocean. Up to 75 % of marine nitrogen fixation may be limited by iron supply due to the relatively high iron requirements of planktonic diazotrophs (Berman-Frank et al., 2001). The deposition of soluble aerosol iron can initiate nitrogen fixation and trigger toxic algal blooms in nitrate-poor tropical waters. There is a large variability in estimates of soluble iron, related to the mixing of aerosol iron sources. Most studies assume that mineral dust represents the primary source of soluble iron in the atmosphere. However, seasonal biomass burning in tropical regions is a potential source of aerosol iron that could explain the large variability of soluble iron in those regions. To investigate aerosol iron sources to the adjacent tropical waters of Australia, the fractional solubility of aerosol iron was determined during the Savannah Fires in the Early Dry Season (SAFIRED) c aign at Gunn Point, Northern Territory, Australia during the dry season in 2014. The source of particulate matter less than 10 µm (PM10) aerosol iron was a mixture of mineral dust, fresh biomass burning aerosol, sea spray and anthropogenic pollution. The mean soluble and total aerosol iron concentrations were 40 and 500 ng m−3 respectively. Fractional Fe solubility was relativity high for the majority of the c aign and averaged 8 % but dropped to 3 % during the largest and most proximal fire event. Fractional Fe solubility and proxies for biomass burning (elemental carbon, levoglucosan, oxalate and carbon monoxide) were unrelated throughout the c aign. An explanation of the lack of correlation between fractional Fe solubility and elemental carbon at the biomass burning source is due to the physical properties of elemental carbon, i.e., fresh elemental carbon aerosols are initially hydrophobic, however they can disperse in water after aging and coating with water soluble species in the atmosphere. Combustion aerosols are thought to have a high factional Fe solubility, which can increase during atmospheric transport from the source. Although, biomass burning derived particles may not be a direct source of soluble iron, they can act indirectly as a surface for aerosols iron to bind during atmospheric transport and subsequently be released to the ocean upon deposition. In addition, biomass burning derived aerosols can indirectly impact the fractional solubility of mineral dust. Fractional Fe solubility was highest during dust events at Gunn Point, and could have been enhanced by mixing with biomass burning derived aerosols. Iron in dust may be more soluble in the tropics compared to higher latitudes due to the presence higher concentrations of biomass burring derived reactive organic species in the atmosphere, such as oxalate, and their potential to enhance the fractional Fe solubility of mineral dust. As the aerosol loading is dominated by biomass burning emissions over the tropical waters in the dry season, additions of biomass burning derived soluble iron could have harmful consequences for initiating nitrogen fixing toxic algal blooms. Future research is required to quantify biomass burning derived particle sources of soluble iron over tropical waters.
Key challenges for tropospheric chemistry in the Southern Hemisphere
Publisher: University of California Press
Date: 2022
DOI: 10.1525/ELEMENTA.2021.00050
Abstract: This commentary paper from the recently formed International Global Atmospheric Chemistry (IGAC) Southern Hemisphere Working Group outlines key issues in atmospheric composition research that particularly impact the Southern Hemisphere. In this article, we present a broad overview of many of the challenges for understanding atmospheric chemistry in the Southern Hemisphere, before focusing in on the most significant factors that differentiate it from the Northern Hemisphere. We present sections on the importance of biogenic emissions and fires in the Southern Hemisphere, showing that these emissions often dominate over anthropogenic emissions in many regions. We then describe how these and other factors influence air quality in different parts of the Southern Hemisphere. Finally, we describe the key role of the Southern Ocean in influencing atmospheric chemistry and conclude with a description of the aims and scope of the newly formed IGAC Southern Hemisphere Working Group.
Observation of sea‐salt fraction in sub‐100 nm diameter particles at Cape Grim
Publisher: American Geophysical Union (AGU)
Date: 04-03-2015
DOI: 10.1002/2014JD022601
Secondary organic aerosol formation from cyclohexene ozonolysis: Effect of OH scavenger and the role of radical chemistry
Publisher: American Chemical Society (ACS)
Date: 15-05-2004
DOI: 10.1021/ES049725J
Abstract: To isolate secondary organic aerosol (SOA) formation in ozone-alkene systems from the additional influence of hydroxyl (OH) radicals formed in the gas-phase ozone-alkene reaction, OH scavengers are employed. The detailed chemistry associated with three different scavengers (cyclohexane, 2-butanol, and CO) is studied in relation to the effects of the scavengers on observed SOA yields in the ozone-cyclohexene system. Our results confirm those of Docherty and Ziemann that the OH scavenger plays a role in SOA formation in alkene ozonolysis. The extent and direction of this influence are shown to be dependent on the specific alkene. The main influence of the scavenger arises from its independent production of HO2 radicals, with CO producing the most HO2, 2-butanol an intermediate amount, and cyclohexane the least. This work provides evidence for the central role of acylperoxy radicals in SOA formation from the ozonolysis of alkenes and generally underscores the importance of gas-phase radical chemistry beyond the initial ozone-alkene reaction.
The MUMBA campaign: measurements of urban, marine and biogenic air
Publisher: Copernicus GmbH
Date: 23-02-2017
DOI: 10.5194/ESSD-2017-14
Abstract: Abstract. The Measurements of Urban, Marine and Biogenic Air (MUMBA) c aign took place in Wollongong, New South Wales (a small coastal city approximately 80 km south of Sydney, Australia), from 21st December 2012 to 15th February 2013. Like many Australian cities, Wollongong is surrounded by dense eucalyptus forest and so the urban air-shed is heavily influenced by biogenic emissions. Instruments were deployed during MUMBA to measure the gaseous and aerosol composition of the atmosphere with the aim of providing a detailed characterisation of the complex environment of the ocean/forest/urban interface that could be used to test the skill of atmospheric models. Gases measured included ozone, oxides of nitrogen, carbon monoxide, carbon dioxide, methane and many of the most abundant volatile organic compounds. Aerosol characterisation included total particle counts above 3 nm, total cloud condensation nuclei counts mass concentration, number concentration size distribution, aerosol chemical analyses and elemental analysis. The c aign captured varied meteorological conditions, including two extreme heat events, providing a potentially valuable test for models of future air quality in a warmer climate. There was also an episode when the site s led clean marine air for many hours, providing a useful additional measure of background concentrations of these trace gases within this poorly s led region of the globe. In this paper we describe the c aign, the meteorology and the resulting observations of atmospheric composition in general terms, in order to equip the reader with sufficient understanding of the Wollongong regional influences to use the MUMBA datasets as a case study for testing a chemical transport model. The data is available from PANGAEA (see doi.pangaea.de/10.1594/PANGAEA.871982).
The WMO Vegetation Fire and Smoke Pollution Warning Advisory and Assessment System (VFSP-WAS): Concept, current capabilities, research and development challenges and the way ahead
Publisher: Copernicus GmbH
Date: 04-03-2021
DOI: 10.5194/EGUSPHERE-EGU21-16504
Abstract: & & Vegetation fires & #8211 including the application of fire in land use, land-use change and uncontrolled wildfire & #8211 affect the functioning of the Earth System and impose significant threats to public health and security.& This paper presents the concept of a Vegetation Fire and Smoke Pollution Warning Advisory and Assessment System (VFSP-WAS& sup& *& /sup& ). It describes the scientific rationale for the system and provides guidance for addressing the issues of vegetation fire and smoke pollution, including key research challenges. The paper& proposes the establishment of VFSP-WAS regional centers and describes& Potential ex les of& this VFSP-WAS concept are described from two regions in (South-East Asia and North America) where regional centers will partner with Regional Fire Monitoring / Fire Management Resource Centers.& & & & *) community.wmo.int/activity-areas/gaw/science/modelling-applications/vfsp-was& & &
Long-distance dispersal maximizes evolutionary potential during rapid geographic range expansion
Publisher: Wiley
Date: 06-11-2013
DOI: 10.1111/MEC.12538
Abstract: Conventional wisdom predicts that sequential founder events will cause genetic ersity to erode in species with expanding geographic ranges, limiting evolutionary potential at the range margin. Here, we show that invasive European starlings (Sturnus vulgaris) in South Africa preserve genetic ersity during range expansion, possibly as a result of frequent long-distance dispersal events. We further show that unfavourable environmental conditions trigger enhanced dispersal, as indicated by signatures of selection detected across the expanding range. This brings genetic variation to the expansion front, counterbalancing the cumulative effects of sequential founding events and optimizing standing genetic ersity and thus evolutionary potential at range margins during spread. Therefore, dispersal strategies should be highlighted as key determinants of the ecological and evolutionary performances of species in novel environments and in response to global environmental change.
Authors repsonse to Reviewer 1
Publisher: Copernicus GmbH
Date: 10-02-2017
Authors Response to Comments from Keith Bigg
Publisher: Copernicus GmbH
Date: 10-02-2017
Multiscale Applications of Two Online-Coupled Meteorology-Chemistry Models during Recent Field Campaigns in Australia, Part I: Model Description and WRF/Chem-ROMS Evaluation Using Surface and Satellite Data and Sensitivity to Spatial Grid Resolutions
Publisher: MDPI AG
Date: 08-04-2019
Abstract: Air pollution and associated human exposure are important research areas in Greater Sydney, Australia. Several field c aigns were conducted to characterize the pollution sources and their impacts on ambient air quality including the Sydney Particle Study Stages 1 and 2 (SPS1 and SPS2), and the Measurements of Urban, Marine, and Biogenic Air (MUMBA). In this work, the Weather Research and Forecasting model with chemistry (WRF/Chem) and the coupled WRF/Chem with the Regional Ocean Model System (ROMS) (WRF/Chem-ROMS) are applied during these field c aigns to assess the models’ capability in reproducing atmospheric observations. The model simulations are performed over quadruple-nested domains at grid resolutions of 81-, 27-, 9-, and 3-km over Australia, an area in southeastern Australia, an area in New South Wales, and the Greater Sydney area, respectively. A comprehensive model evaluation is conducted using surface observations from these field c aigns, satellite retrievals, and other data. This paper evaluates the performance of WRF/Chem-ROMS and its sensitivity to spatial grid resolutions. The model generally performs well at 3-, 9-, and 27-km resolutions for sea-surface temperature and boundary layer meteorology in terms of performance statistics, seasonality, and daily variation. Moderate biases occur for temperature at 2-m and wind speed at 10-m in the mornings and evenings due to the inaccurate representation of the nocturnal boundary layer and surface heat fluxes. Larger underpredictions occur for total precipitation due to the limitations of the cloud microphysics scheme or cumulus parameterization. The model performs well at 3-, 9-, and 27-km resolutions for surface O3 in terms of statistics, spatial distributions, and diurnal and daily variations. The model underpredicts PM2.5 and PM10 during SPS1 and MUMBA but overpredicts PM2.5 and underpredicts PM10 during SPS2. These biases are attributed to inaccurate meteorology, precursor emissions, insufficient SO2 conversion to sulfate, inadequate dispersion at finer grid resolutions, and underprediction in secondary organic aerosol. The model gives moderate biases for net shortwave radiation and cloud condensation nuclei but large biases for other radiative and cloud variables. The performance of aerosol optical depth and latent/sensible heat flux varies for different simulation periods. Among all variables evaluated, wind speed at 10-m, precipitation, surface concentrations of CO, NO, NO2, SO2, O3, PM2.5, and PM10, aerosol optical depth, cloud optical thickness, cloud condensation nuclei, and column NO2 show moderate-to-strong sensitivity to spatial grid resolutions. The use of finer grid resolutions (3- or 9-km) can generally improve the performance for those variables. While the performance for most of these variables is consistent with that over the U.S. and East Asia, several differences along with future work are identified to pinpoint reasons for such differences.
Observations of Ice Nucleating Particles Over Southern Ocean Waters
Publisher: American Geophysical Union (AGU)
Date: 05-11-2018
DOI: 10.1029/2018GL079981
Upper Hunter Valley Particle Characterization Study : 3rd Progress Report
Publisher: CSIRO
Date: 2013
Particle formation in a complex environment
Publisher: MDPI AG
Date: 14-05-2019
Abstract: A field aerosol measurement c aign as part of the Measurements of Urban, Marine and Biogenic Air (MUMBA) c aign was conducted between 16 January 2013 and 15 February 2013 in the coastal city of Wollongong, Australia. The objectives of this research were to study the occurrence frequency, characteristics and factors that influence new particle formation processes. Particle formation and growth events were observed from particle number size distribution data in the range of 14 nm–660 nm measured using a scanning particle mobility sizer (SMPS). Four weak Class I particle formation and growth event days were observed, which is equivalent to 13% of the total observation days. The events occurred during the day, starting after 8:30 Australian Eastern Standard time with an average duration of five hours. The events also appeared to be positively linked to the prevailing easterly to north easterly sea breezes that carry pollutants from sources in and around Sydney. This suggests that photochemical reactions and a combination of oceanic and anthropogenic air masses are among the factors that influenced these events.
Modelling PM10 concentrations and carrying capacity associated with woodheater emissions in Launceston, Tasmania
Publisher: Elsevier BV
Date: 09-2006
Measurements of air quality at a hydraulic fracturing site in the Surat Basin, Queensland- Draft Final Report Task 2 Report for Project W.12 Air, water and soil impacts of hydraulic fracturing: Phase 2
Publisher: CSIRO
Date: 2019
Aerosol samplers and chemical composition
Publisher: Australian Bureau of Meteorology and CSIRO Marine and Atmospheric Research
Date: 2014
DOI: 10.25919/CH48-2E05
Multidecadal trend analysis of aerosol radiative properties at a global scale
Publisher: Copernicus GmbH
Date: 14-01-2020
Abstract: Abstract. In order to assess the global evolution of aerosol parameters affecting climate change, a long-term trend analyses of aerosol optical properties were performed on time series from 52 stations situated across five continents. The time series of measured scattering, backscattering and absorption coefficients as well as the derived single scattering albedo, backscattering fraction, scattering and absorption Ångström exponents covered at least 10 years and up to 40 years for some stations. The non-parametric seasonal Mann–Kendall (MK) statistical test associated with several prewhitening methods and with the Sen's slope were used as main trend analysis methods. Comparisons with General Least Mean Square associated with Autoregressive Bootstrap (GLS/ARB) and with standard Least Mean Square analysis (LMS) enabled confirmation of the detected MK statistically significant trends and the assessment of advantages and limitations of each method. Currently, scattering and backscattering coefficients trends are mostly decreasing in Europe and North America and are not statistically significant in Asia, while polar stations exhibit a mix of increasing and decreasing trends. A few increasing trends are also found at some stations in North America and Australia. Absorption coefficients time series also exhibit primarily decreasing trends. For single scattering albedo, 52 % of the sites exhibit statistically significant positive trends, mostly in Asia, Eastern/Northern Europe and Arctic, 18 % of sites exhibit statistically significant negative trends, mostly in central Europe and central North America, while the remaining 30 % of sites have trends, which are not statistically significant. In addition to evaluating trends for the overall time series, the evolution of the trends in sequential 10 year segments was also analyzed. For scattering and backscattering, statistically significant increasing 10 year trends are primarily found for earlier periods (10 year trends ending in 2010–2015) for polar stations and Mauna Loa. For most of the stations, the present-day statistically significant decreasing 10 year trends of the single scattering albedo were preceded by not statistically significant and statistically significant increasing 10 year trends. The effect of air pollution abatement policies in continental North America is very obvious in the 10 year trends of the scattering coefficient – there is a shift to statistically significant negative trends in 2010–2011 for all stations in the eastern and central US. This long-term trend analysis of aerosol radiative properties with a broad spatial coverage enables a better global view of potential aerosol effects on climate changes.
Composition, size and cloud condensation nuclei activity of biomass burning aerosol from northern Australian savannah fires
Publisher: Copernicus GmbH
Date: 14-03-2017
Abstract: Abstract. The vast majority of Australia's fires occur in the tropical north of the continent during the dry season. These fires are a significant source of aerosol and cloud condensation nuclei (CCN) in the region, providing a unique opportunity to investigate the biomass burning aerosol (BBA) in the absence of other sources. CCN concentrations at 0.5 % supersaturation and aerosol size and chemical properties were measured at the Australian Tropical Atmospheric Research Station (ATARS) during June 2014. CCN concentrations reached over 104 cm−3 when frequent and close fires were burning – up to 45 times higher than periods with no fires. Both the size distribution and composition of BBA appeared to significantly influence CCN concentrations. A distinct diurnal trend in the proportion of BBA activating to cloud droplets was observed, with an activation ratio of 40 ± 20 % during the night and 60 ± 20 % during the day. BBA was, on average, less hygroscopic during the night (κ = 0. 04 ± 0.03) than during the day (κ = 0.07 ± 0.05), with a maximum typically observed just before midday. Size-resolved composition of BBA showed that organics comprised a constant 90 % of the aerosol volume for aerodynamic diameters between 100 and 200 nm. While this suggests that the photochemical oxidation of organics led to an increase in the hygroscopic growth and an increase in daytime activation ratios, it does not explain the decrease in hygroscopicity after midday. Modelled CCN concentrations assuming typical continental hygroscopicities produced very large overestimations of up to 200 %. Smaller, but still significant, overpredictions up to ∼ 100 % were observed using aerosol mass spectrometer (AMS)- and hygroscopicity tandem differential mobility analyser (H-TDMA)-derived hygroscopicities as well as c aign night and day averages. The largest estimations in every case occurred during the night, when the small variations in very weakly hygroscopic species corresponded to large variations in the activation diameters. Trade winds carry the smoke generated from these fires over the Timor Sea, where aerosol–cloud interactions are likely to be sensitive to changes in CCN concentrations, perturbing cloud albedo and lifetime. Dry season fires in northern Australia are therefore potentially very important in cloud processes in this region.
Shipborne observations of the radiative effect of Southern Ocean clouds
Publisher: American Geophysical Union (AGU)
Date: 04-01-2017
DOI: 10.1002/2016JD026061
Impact of biomass burning sources on seasonal aerosol air quality
Publisher: Elsevier BV
Date: 03-2013
Bushfire smoke plume composition and toxicological assessment from the 2019–2020 Australian Black Summer
Publisher: Springer Science and Business Media LLC
Date: 08-12-2022
DOI: 10.1007/S11869-022-01237-5
Abstract: Many of the population centres in southeast Australia were swathed in bushfire smoke during the 2019–2020 austral summer. Bushfires burning during what is now known as the Black Summer was historically large and severe, and the fire season historically long. The chemical composition in the gas and aerosol phase of aged plumes measured near Wollongong, NSW in early 2020 is reported in this work. Enhancement ratios to carbon monoxide are presented for thirteen species (acetaldehyde, acetone, acetonitrile, black carbon aerosol, benzene, methane, methacrolein + methyl vinyl ketone, methyl ethyl ketone, methanol, ammonium ion PM 1 fraction, nitrate ion PM 1 fraction, organic PM 1 fraction and PM 2.5 ). Observed plume composition is comparable to that measured in fresh smoke from Australian fires reported in the literature. Enhancements of biogenic volatile organic compounds such as isoprene (smoke-effected period mean 1 ppb, maximum 6 ppb) were observed along with elevated concentrations of particulate variables. Enhancement ratios reported here can be used in plume modelling of landscape-scale fires and assist in concentration estimates of infrequently measured atmospheric pollutants. The relative toxicological contribution of species present in the plumes was determined for plume exposure at the measurement site and for concentrated plumes at a population centre case study. Similar results were apparent at both locations. Contributions to the toxicological loading were dominated by respirable particles (~ 52–63% total contribution), formaldehyde (~ 30–39% total contribution) and acrolein. This is a reminder to consider the toxicological contributions in the gas phase when considering health impacts of population exposure to bushfire smoke.
New particle formation in China: Current knowledge and further directions
Publisher: Elsevier BV
Date: 2017
DOI: 10.1016/J.SCITOTENV.2016.10.177
Abstract: New particle formation (NPF) studies have been conducted in China since 2004. Formation of new atmospheric aerosol particles has been observed to take place in erse environments, even under the circumstances of high pre-existing particle loading, challenging the traditional and present understanding of the physicochemical nucleation mechanisms, which have been proposed based on the investigations in clean environments and under laboratory experimental conditions. This paper summarizes the present status and gaps in understanding NPF in China and discusses the main directions opening for future research.
Comprehensive aerosol and gas data set from the Sydney Particle Study
Publisher: Copernicus GmbH
Date: 02-12-2019
DOI: 10.5194/ESSD-11-1883-2019
Abstract: Abstract. The Sydney Particle Study involved the comprehensive measurement of meteorology, particles and gases at a location in western Sydney during February–March 2011 and April–May 2012. The aim of this study was to increase scientific understanding of particle formation and transformations in the Sydney airshed. In this paper we describe the methods used to collect and analyse particle and gaseous s les, as well as the methods employed for the continuous measurement of particle concentrations, particle microphysical properties, and gaseous concentrations. This paper also provides a description of the data collected and is a metadata record for the data sets published in Keywood et al. (2016a, 0.4225/08/57903B83D6A5D) and Keywood et al. (2016b, 0.4225/08/5791B5528BD63).
Supplementary material to "Suitability of high-volume aerosol samplers for ultra-trace aerosol iron measurements in pristine air masses: blanks, recoveries and bugs"
Publisher: Copernicus GmbH
Date: 08-04-2016
Forest Fire Smoke Exposures and Out-of-Hospital Cardiac Arrests in Melbourne, Australia: A Case-Crossover Study
Publisher: Environmental Health Perspectives
Date: 10-2015
DOI: 10.1289/EHP.1408436
Unexpectedly high ultrafine aerosol concentrations above East Antarctic sea-ice
Publisher: Copernicus GmbH
Date: 27-10-2015
DOI: 10.5194/ACPD-15-29125-2015
Abstract: Abstract. The effect of aerosols on clouds and their radiative properties is one of the largest uncertainties in our understanding of radiative forcing. A recent study has concluded that better characterisation of pristine, natural aerosol processes leads to the largest reduction in these uncertainties. Antarctica, being far from anthropogenic activities, is an ideal location for the study of natural aerosol processes. Aerosol measurements in Antarctica are often limited to boundary layer air-masses at spatially sparse coastal and continental research stations, with only a handful of studies in the sea ice region. In this paper, the first observational study of sub-micron aerosols in the East Antarctic sea ice region is presented. Measurements were conducted aboard the ice-breaker Aurora Australis in spring 2012 and found that boundary layer condensation nuclei (CN3) concentrations exhibited a five-fold increase moving across the Polar Front, with mean Polar Cell concentrations of 1130 cm−3 – higher than any observed elsewhere in the Antarctic and Southern Ocean region. The absence of evidence for aerosol growth suggested that nucleation was unlikely to be local. Air parcel trajectories indicated significant influence from the free troposphere above the Antarctic continent, implicating this as the likely nucleation region for surface aerosol, a similar conclusion to previous Antarctic aerosol studies. The highest aerosol concentrations were found to correlate with low pressure systems, suggesting that the passage of cyclones provided an accelerated pathway, delivering air-masses quickly from the free-troposphere to the surface. After descent from the Antarctic free troposphere, trajectories suggest that sea ice boundary layer air-masses travelled equator-ward into the low albedo Southern Ocean region, transporting with them emissions and these aerosol nuclei where, after growth, may potentially impact on the region's radiative balance. The high aerosol concentrations and their transport pathways described here, could help reduce the discrepancy currently present between simulations and observations of cloud and aerosol over the Southern Ocean.
Composition of Clean Marine Air and Biogenic Influences on VOCs during the MUMBA Campaign
Publisher: MDPI AG
Date: 10-09-2019
Abstract: Volatile organic compounds (VOCs) are important precursors to the formation of ozone and fine particulate matter, the two pollutants of most concern in Sydney, Australia. Despite this importance, there are very few published measurements of ambient VOC concentrations in Australia. In this paper, we present mole fractions of several important VOCs measured during the c aign known as MUMBA (Measurements of Urban, Marine and Biogenic Air) in the Australian city of Wollongong (34°S). We particularly focus on measurements made during periods when clean marine air impacted the measurement site and on VOCs of biogenic origin. Typical unpolluted marine air mole fractions during austral summer 2012-2013 at latitude 34°S were established for CO2 (391.0 ± 0.6 ppm), CH4 (1760.1 ± 0.4 ppb), N2O (325.04 ± 0.08 ppb), CO (52.4 ± 1.7 ppb), O3 (20.5 ± 1.1 ppb), acetaldehyde (190 ± 40 ppt), acetone (260 ± 30 ppt), dimethyl sulphide (50 ± 10 ppt), benzene (20 ± 10 ppt), toluene (30 ± 20 ppt), C8H10 aromatics (23 ± 6 ppt) and C9H12 aromatics (36 ± 7 ppt). The MUMBA site was frequently influenced by VOCs of biogenic origin from a nearby strip of forested parkland to the east due to the dominant north-easterly afternoon sea breeze. VOCs from the more distant densely forested escarpment to the west also impacted the site, especially during two days of extreme heat and strong westerly winds. The relative amounts of different biogenic VOCs observed for these two biomes differed, with much larger increases of isoprene than of monoterpenes or methanol during the hot westerly winds from the escarpment than with cooler winds from the east. However, whether this was due to different vegetation types or was solely the result of the extreme temperatures is not entirely clear. We conclude that the clean marine air and biogenic signatures measured during the MUMBA c aign provide useful information about the typical abundance of several key VOCs and can be used to constrain chemical transport model simulations of the atmosphere in this poorly s led region of the world.
Biomass burning emissions of trace gases and particles in marine air at Cape Grim, Tasmania
Publisher: Copernicus GmbH
Date: 07-12-2015
DOI: 10.5194/ACP-15-13393-2015
Abstract: Abstract. Biomass burning (BB) plumes were measured at the Cape Grim Baseline Air Pollution Station during the 2006 Precursors to Particles c aign, when emissions from a fire on nearby Robbins Island impacted the station. Measurements made included non-methane organic compounds (NMOCs) (PTR-MS), particle number size distribution, condensation nuclei (CN) 3 nm, black carbon (BC) concentration, cloud condensation nuclei (CCN) number, ozone (O3), methane (CH4), carbon monoxide (CO), hydrogen (H2), carbon dioxide (CO2), nitrous oxide (N2O), halocarbons and meteorology. During the first plume strike event (BB1), a 4 h enhancement of CO (max ~ 2100 ppb), BC (~ 1400 ng m-3) and particles 3 nm (~ 13 000 cm-3) with dominant particle mode of 120 nm were observed overnight. A wind direction change lead to a dramatic reduction in BB tracers and a drop in the dominant particle mode to 50 nm. The dominant mode increased in size to 80 nm over 5 h in calm sunny conditions, accompanied by an increase in ozone. Due to an enhancement in BC but not CO during particle growth, the presence of BB emissions during this period could not be confirmed. The ability of particles 80 nm (CN80) to act as CCN at 0.5 % supersaturation was investigated. The ΔCCN / ΔCN80 ratio was lowest during the fresh BB plume (56 ± 8 %), higher during the particle growth period (77 ± 4 %) and higher still (104 ± 3 %) in background marine air. Particle size distributions indicate that changes to particle chemical composition, rather than particle size, are driving these changes. Hourly average CCN during both BB events were between 2000 and 5000 CCN cm-3, which were enhanced above typical background levels by a factor of 6–34, highlighting the dramatic impact BB plumes can have on CCN number in clean marine regions. During the 29 h of the second plume strike event (BB2) CO, BC and a range of NMOCs including acetonitrile and hydrogen cyanide (HCN) were clearly enhanced and some enhancements in O3 were observed (ΔO3 / ΔCO 0.001–0.074). A short-lived increase in NMOCs by a factor of 10 corresponded with a large CO enhancement, an increase of the NMOC / CO emission ratio (ER) by a factor of 2–4 and a halving of the BC / CO ratio. Rainfall on Robbins Island was observed by radar during this period which likely resulted in a lower fire combustion efficiency, and higher emission of compounds associated with smouldering. This highlights the importance of relatively minor meteorological events on BB emission ratios. Emission factors (EFs) were derived for a range of trace gases, some never before reported for Australian fires, (including hydrogen, phenol and toluene) using the carbon mass balance method. This provides a unique set of EFs for Australian coastal heathland fires. Methyl halide EFs were higher than EFs reported from other studies in Australia and the Northern Hemisphere which is likely due to high halogen content in vegetation on Robbins Island. This work demonstrates the substantial impact that BB plumes can have on the composition of marine air, and the significant changes that can occur as the plume interacts with terrestrial, aged urban and marine emission sources.
Emission factors of trace gases and particles from tropical savanna fires in Australia
Publisher: American Geophysical Union (AGU)
Date: 10-06-2017
DOI: 10.1002/2016JD025925
Haze in the Klang Valley of Malaysia
Publisher: Copernicus GmbH
Date: 05-06-2003
Abstract: Abstract. Continuous measurements of dry aerosol light scattering (Bsp) were made at two sites in the Klang Valley of Malaysia between December 1998 and December 2000. In addition 24-hour PM2.5 s les were collected on a one-day-in-six cycle and the chemical composition of the aerosol was determined. Periods of excessive haze were defined as 24-hour average Bsp values greater than 150 Mm-1 and these occurred on a number of occasions, between May and September 1999, during May 2000, and between July and September 2000. The evidence for smoke from biomass burning being a significant contributor to aerosol during periods of excessive haze is discussed. For ex le, during periods of excessive haze, the chemical composition of the aerosol showed enhanced concentrations of elemental carbon, organic carbon and non-seasalt potassium. The diurnal cycle of Bsp and PM10 was disturbed from its usual pattern of maxima overnight and minuma during the day with morning and afternoon traffic peaks, and instead showed a maximum peak during the middle of the day. Periods of excessive haze were coincident with the presence of forest fires on Sumatra during the southwest (SW) monsoon period, the influence of which are demonstrated by transport modelling for one week of the SW monsoon of 2000. The study highlights that whilst transboundary smoke is a major contributor to poor visibility in the Klang Valley, smoke from fires on Peninsular Malaysia is also a contributor. In addition the uniform concentration of non-seasalt sulfate in PM2.5 at both sites over the entire s ling period suggests the presence of a domestic source of secondary aerosol production in the Klang Valley.
Precursors to Particles (P2P) at Cape Grim 2006: campaign overview
Publisher: CSIRO Publishing
Date: 2007
DOI: 10.1071/EN07041
Abstract: Environmental context. Understanding the role of clouds in assessing the impact of climate change is a challenging issue. It is thought that plankton and seaweed contribute to the formation of clouds by emitting gases that lead to the particle production necessary for cloud formation. Macroalgae (kelp) at Mace Head, Ireland, produce large quantities of iodine when exposed to sunlight at low tide and this iodine results in the rapid production of particles. Cape Grim, Tasmania, also has large colonies of kelp and the role of Bull Kelp (Durvillaea potatorum) in particle production was assessed. Abstract. Iodine emissions from coastal macroalgae have been found to be important initiators for nucleation events at Mace Head, Ireland. The source of this iodine is the large beds of the brown kelp Laminaria digitata, which are significantly exposed at low tide. On the coast around Cape Grim, Tasmania, there are beds of the brown kelp Durvillaea potatrum. The Precursors to Particles 2006 (P2P 2006) c aign at the Cape Grim Baseline Air Pollution Station in late summer (February) 2006 focused on the role of this local kelp in providing precursor gases to particle formation. Durvillaea potatorum does not produce iodated precursor gases at the levels observed at Mace Head. IO was measured at 0.5 ± 0.3 ppt, while OIO was below detection limits (9 ppt). The dominant atmospheric iodated species was methyl iodide and the average concentration measured at the Cape Grim Station was 1.5 ± 0.3 pptv in baseline conditions, but showed significant variation in discrete s les collected immediately above the ocean surface. Nucleation events were not detected at the Cape Grim Station, except for one period where the plume of a local bushfire interacted with air of marine origin. The passage of four fronts did not result in nucleation bursts and measurements on the beach 94 m below the Cape Grim Station suggested that Durvillaea potatorum was only a weak source of new particles.
Contribution of first- versus second-generation products to secondary organic aerosols formed in the oxidation of biogenic hydrocarbons
Publisher: American Chemical Society (ACS)
Date: 04-03-2006
DOI: 10.1021/ES052269U
Abstract: Biogenic hydrocarbons emitted by vegetation are important contributors to secondary organic aerosol (SOA), but the aerosol formation mechanisms are incompletely understood. In this study, the formation of aerosols and gas-phase products from the ozonolysis and photooxidation of a series of biogenic hydrocarbons (isoprene, 8 monoterpenes, 4 sesquiterpenes, and 3 oxygenated terpenes) are examined. By comparing aerosol growth (measured by Differential Mobility Analyzers, DMAs) and gas-phase concentrations (monitored by a Proton Transfer Reaction Mass Spectrometer, PTR-MS), we study the general mechanisms of SOA formation. Aerosol growth data are presented in terms of a "growth curve", a plot of aerosol mass formed versus the amount of hydrocarbon reacted. From the shapes of the growth curves, it is found that all the hydrocarbons studied can be classified into two groups based entirely on the number of double bonds of the hydrocarbon, regardless of the reaction systems (ozonolysis or photooxidation) and the types of hydrocarbons studied: compounds with only one double bond and compounds with more than one double bond. For compounds with only one double bond, the first oxidation step is rate-limiting, and aerosols are formed mainly from low volatility first-generation oxidation products whereas for compounds with more than one double bond, the second oxidation step may also be rate-limiting and second-generation products contribute substantially to SOA growth. This behavior is characterized by a vertical section in the growth curve, in which continued aerosol growth is observed even after all the parent hydrocarbon is consumed.
Supplementary material to "Current estimates of biogenic emissions from Eucalypts uncertain for Southeast Australia"
Publisher: Copernicus GmbH
Date: 03-2016
Characterization of primary and secondary organic aerosols in Melbourne airshed: The influence of biogenic emissions, wood smoke and bushfires
Publisher: Elsevier BV
Date: 04-2016
Atmospheric short-chain-chlorinated paraffins in Melbourne, Australia – first extensive Southern Hemisphere observations
Publisher: CSIRO Publishing
Date: 2017
DOI: 10.1071/EN16152
Abstract: Environmental contextThis study presents the first comprehensive set of ambient atmospheric concentrations of short-chain-chlorinated paraffins in the Southern Hemisphere. The data show a seasonal cycle with a summer maximum and a winter minimum. The seasonal cycle is consistent with temperature dependence of the vapour pressure of the short-chain-chlorinated paraffins resulting in partitioning between the atmosphere and other reservoirs with a secondary modulation by soil moisture. AbstractThe first extensive measurements of short-chain chlorinated paraffins (SCCPs) in the atmosphere of the Southern Hemisphere are presented. The analytical and s ling methodologies used in this Australian study were verified by systematic testing along with two inter-comparisons with Northern Hemisphere laboratories with established SCCP programs. In the ambient atmosphere of Melbourne, Australia, in 2013–14, there was a clear seasonal cycle in SCCP monthly averaged concentrations, these ranging from 28.4ng m–3 in summer to 1.8ng m–3 in winter. Air temperature was the factor most closely related to the seasonal cycle in SCCPs in Melbourne. The average SCCP concentrations observed indoors were less than those observed outdoors. Atmospheric concentrations of SCCPs in Melbourne are more than two orders of magnitude higher than concentrations in the background atmosphere. Surprisingly, the SCCP concentrations in Melbourne are similar to those observed in cities in Japan, South Korea and the United Kingdom, and less than those observed in China. Direct transport of SCCPs in the atmosphere from the Northern Hemisphere emissions to Melbourne is ruled out. Instead elevated concentrations in the Melbourne air-shed are most likely a result of the long-term import of SCCPs as industrial chemicals and within manufactured materials from the Northern Hemisphere so that the use of SCCPs in Melbourne and their consequent release to the environment has produced environmental reservoirs of SCCPs in Melbourne that are comparable with those in some Northern Hemisphere cities. The increase in SCCP concentrations from winter to summer is consistent with the temperature dependence of partitioning of SCCPs between the atmosphere and other reservoirs. Insufficient information exists on SCCP use and its presence in soils and sediments in Australia to indicate whether the atmospheric presence of SCCPs in Melbourne is a legacy issue due to its import and use as a metal cutting agent in past decades or due to ongoing imports of manufactured materials containing SCCPs today.
Boundary layer new particle formation over East Antarctic sea ice – possible Hg-driven nucleation?
Publisher: Copernicus GmbH
Date: 02-12-2015
DOI: 10.5194/ACP-15-13339-2015
Abstract: Abstract. Aerosol observations above the Southern Ocean and Antarctic sea ice are scarce. Measurements of aerosols and atmospheric composition were made in East Antarctic pack ice on board the Australian icebreaker Aurora Australis during the spring of 2012. One particle formation event was observed during the 32 days of observations. This event occurred on the only day to exhibit extended periods of global irradiance in excess of 600 W m−2. Within the single air mass influencing the measurements, number concentrations of particles larger than 3 nm (CN3) reached almost 7700 cm−3 within a few hours of clouds clearing, and grew at rates of 5.6 nm h−1. Formation rates of 3 nm particles were in the range of those measured at other Antarctic locations at 0.2–1.1 ± 0.1 cm−3 s−1. Our investigations into the nucleation chemistry found that there were insufficient precursor concentrations for known halogen or organic chemistry to explain the nucleation event. Modelling studies utilising known sulfuric acid nucleation schemes could not simultaneously reproduce both particle formation or growth rates. Surprising correlations with total gaseous mercury (TGM) were found that, together with other data, suggest a mercury-driven photochemical nucleation mechanism may be responsible for aerosol nucleation. Given the very low vapour pressures of the mercury species involved, this nucleation chemistry is likely only possible where pre-existing aerosol concentrations are low and both TGM concentrations and solar radiation levels are relatively high (∼ 1.5 ng m−3 and & geq 600 W m−2, respectively), such as those observed in the Antarctic sea ice boundary layer in this study or in the global free troposphere, particularly in the Northern Hemisphere.
Related Organisations
Commonwealth Scientific And Industrial Research Organisation
Location: Australia
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