ORCID Profile
0000-0002-9710-9832
Current Organisations
Karolinska Institute
,
PPD SKANDINAVIEN
,
CSIRO
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Publisher: CSIRO Publishing
Date: 09-03-2023
DOI: 10.1071/RJ22028
Abstract: Since the mid-1970s, approximately 250 000 ha of rangelands in semi-arid far south-western NSW, Australia, have been converted to cropping land use, resulting in substantial wind erosion. Wind erosion is of concern because of its adverse impacts on soils, agricultural production, aviation, energy supply, human health and ecosystem function. Over recent decades, multi-faceted extension programs have promoted sustainable land management practices to reduce wind erosion. Repeated biannual paddock surveys were undertaken between 2003 and 2022 to determine (1) the best land management practices (BMPs), that is, those that would reduce erosion while maintaining productivity and profitability, and (2) whether the use of the BMPs changed over time. The BMPs that reduce wind erosion included chemical fallow, standing stubble, and perennial pastures. Between 2003 and 2022, the proportion of sites with BMPs increased from 14% to 75%, and the proportion of sites with wind erosion fell from 23% to 9%. Practices that reduced ground cover and led to frequent erosion have declined, including tilled pasture, tilled stubble and grazed stubble. In drier years, livestock grazing crop stubble exacerbated the erosion hazard. In an attempt to understand where landholders obtain their information for land management practice change, the Western Local Land Services (LLS) conducted a social benchmarking survey in 2020 that indicated that the LLS was the third source of information for practice change after neighbours and other landholders, and stock and station agents. Although the LLS is a source of information, this study could not determine a causal link between LLS programs and practice change. Further research is required to test whether extension programs can reduce the overgrazing of stubble.
Publisher: CSIRO Publishing
Date: 27-04-2023
DOI: 10.1071/RJ22059
Abstract: This study assessed whether dust-storm frequency during major droughts in New South Wales (NSW), Australia, has changed and what may have caused any change. The frequency of days with dust storms, i.e. when visibility is m, is presented for the dust storm year (July to June), with the maximum number of dust storms for three major droughts, namely, 2017/20, Millennial and World War II droughts. Community attitudes, government policy and land management practices have changed since the 1940s, and these factors were reviewed to determine whether they explain changes in dust-storm frequency. Two data sources were used: meteorological weather codes from the Australian Bureau of Meteorology and dust particulate matter µm (PM10) from the DustWatch/Rural Air Quality Monitoring Network. The particulate-matter data were converted to dust-storm days (DSD) to create a yearly time series. The meteorological data records were coded as dust storms and required no modification. Results showed that 1944/45 was the dustiest year, with 4.4 times more DSD than in 2019/20 and 9.9 times more DSD than in 2009/10. One reason for the higher DSD in 2019/20 than in 2009/10 was the area protected from wind erosion by vegetation cover above 50%. In 2019/20, 69% of NSW was protected from wind erosion, compared with 79% in 2009/10. We suggest the primary reasons for lower DSD in 2019/20 and 2009/10 than in 1944/45 were community attitudes, government policy and land management practices these, in combination, help maintain vegetation cover. Since the 1940s, the focus of land management has changed from ‘taming the land’ to ‘sustainably using the land’. Government policy in the 2000s is focused on supporting farming businesses and communities to manage and prepare so as to successfully manage drought. Land management practices that maintain ground cover are now widely practised.
Publisher: American Geophysical Union (AGU)
Date: 07-09-2023
DOI: 10.1029/2023JD038584
Abstract: Large‐scale classical dust cycle models, developed more than two decades ago, assume for simplicity that the Earth’s land surface is devoid of vegetation, reduce dust emission estimates using a vegetation cover complement, and calibrate estimates to observed atmospheric dust optical depth (DOD). Consequently, these models are expected to be valid for use with dust‐climate projections in Earth System Models. We reveal little spatial relation between DOD frequency and satellite observed dust emission from point sources (DPS) and a difference of up to two orders of magnitude. We compared DPS data to an exemplar traditional dust emission model (TEM) and the albedo‐based dust emission model (AEM) which represents aerodynamic roughness over space and time. Both models over‐estimated dust emission probability but showed strong spatial relations to DPS, suitable for calibration. Relative to the AEM calibrated to the DPS, the TEM over‐estimated large dust emission over vast vegetated areas and produced considerable false change in dust emission. It is difficult to avoid the conclusion that calibrating dust cycle models to DOD has hidden for more than two decades, these TEM modelling weaknesses. The AEM overcomes these weaknesses without using masks or vegetation cover data. Considerable potential therefore exists for ESMs driven by prognostic albedo, to reveal new insights of aerosol effects on, and responses to, contemporary and environmental change projections.
Publisher: Frontiers Media SA
Date: 12-09-2018
Publisher: MDPI AG
Date: 22-01-2021
Abstract: Dust storms originating from Central Australia and western New South Wales frequently cause high particle concentrations at many sites across New South Wales, both inland and along the coast. This study focussed on a dust storm event in February 2019 which affected air quality across the state as detected at many ambient monitoring stations in the Department of Planning, Industry and Environment (DPIE) air quality monitoring network. The WRF-Chem (Weather Research and Forecast Model—Chemistry) model is used to study the formation, dispersion and transport of dust across the state of New South Wales (NSW, Australia). Wildfires also happened in northern NSW at the same time of the dust storm in February 2019, and their emissions are taken into account in the WRF-Chem model by using Fire Inventory from NCAR (FINN) as emission input. The model performance is evaluated and is shown to predict fairly accurate the PM2.5 and PM10 concentration as compared to observation. The predicted PM2.5 concentration over New South Wales during 5 days from 11 to 15 February 2019 is then used to estimate the impact of the February 2019 dust storm event on three health endpoints, namely mortality, respiratory and cardiac disease hospitalisation rates. The results show that even though as the daily average of PM2.5 over some parts of the state, especially in western and north western NSW near the centre of the dust storm and wild fires, are very high (over 900 µg/m3), the population exposure is low due to the sparse population. Generally, the health impact is similar in order of magnitude to that caused by biomass burning events from wildfires or from hazardous reduction burnings (HRBs) near populous centres such as in Sydney in May 2016. One notable difference is the higher respiratory disease hospitalisation for this dust event (161) compared to the fire event (24).
Publisher: Elsevier BV
Date: 02-2023
Location: Australia
No related grants have been discovered for John Leys.