ORCID Profile
0000-0002-5129-7719
Current Organisation
Monash University
Does something not look right? The information on this page has been harvested from data sources that may not be up to date. We continue to work with information providers to improve coverage and quality. To report an issue, use the Feedback Form.
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)
Climate Change Processes | Atmospheric Sciences | Atmospheric Dynamics | Physical Oceanography | Palaeoclimatology | Ecological Impacts of Climate Change | Geology | Ecological Applications | Landscape Ecology | Atmospheric Sciences not elsewhere classified | Meteorology | Cloud Physics | Tectonics
ANZSRC Socio-Economic Objective (SEO)
Climate Change Models | Effects of Climate Change and Variability on Australia (excl. Social Impacts) | Atmospheric Processes and Dynamics | Climate Variability (excl. Social Impacts) | Ecosystem Assessment and Management at Regional or Larger Scales | Natural Hazards in Coastal and Estuarine Environments | Global Effects of Climate Change and Variability (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. Social Impacts) | Expanding Knowledge in the Environmental Sciences | Expanding Knowledge in the Earth Sciences | Expanding Knowledge in the Information and Computing Sciences | Flora, Fauna and Biodiversity at Regional or Larger Scales |
Related Links
Publications
Atmosphere-only GCM simulations with prescribed land surface temperatures
Publisher: Copernicus GmbH
Date: 19-01-2016
DOI: 10.5194/GMD-2016-6
Abstract: Abstract. General circulation models (GCMs) are valuable tools for understanding how the global ocean-atmosphere-land surface system interacts and are routinely evaluated relative to observational datasets. Conversely, observational datasets can also be used to constrain GCMs in order to identify systematic errors in their simulated climates. One such ex le is to prescribe sea surface temperatures (SSTs) such that 70% of the Earth’s surface temperature field is observationally constrained (known as an Atmospheric Model Intercomparison Project, AMIP, simulation). Nevertheless, in such simulations, land surface temperatures are typically allowed to vary freely and therefore any errors that develop over the land may affect the global circulation. In this study therefore, a method for prescribing the land surface temperatures within a GCM (the Australian Community Climate and Earth System Simulator, ACCESS) is presented. Simulations with this prescribed land temperature model produce a mean climate state that is comparable to a simulation with freely varying land temperatures for ex le the diurnal cycle of tropical convection is maintained. The model is then developed further to incorporate a selection of "proof of concept" sensitivity experiments where the land surface temperatures are changed globally and regionally. The resulting changes to the global circulation in these sensitivity experiments are found to be consistent with other idealised model experiments described in the wider scientific literature. Finally, a list of other potential applications are described at the end of the study to highlight the usefulness of such a model to the scientific community.
Amplification of El Niño by cloud longwave coupling to atmospheric circulation
Publisher: Springer Science and Business Media LLC
Date: 04-01-2016
DOI: 10.1038/NGEO2630
An evaluation of the CMIP3 and CMIP5 simulations in their skill of simulating the spatial structure of SST variability
Publisher: Springer Science and Business Media LLC
Date: 09-05-2014
The Tropospheric Land–Sea Warming Contrast as the Driver of Tropical Sea Level Pressure Changes
Publisher: American Meteorological Society
Date: 15-02-2013
DOI: 10.1175/JCLI-D-11-00731.1
Abstract: This article addresses the causes of the large-scale tropical sea level pressure (SLP) changes during climate change. The analysis presented here is based on model simulations, observed trends, and the seasonal cycle. In all three cases the regional changes of tropospheric temperature (Ttropos) and SLP are strongly related to each other [considerably more strongly than (sea) surface temperature and SLP]. This relationship basically follows the Bjerknes circulation theorem, with relatively low regional SLP where there is relatively high Ttropos and vice versa. A simple physical model suggests a tropical SLP response to horizontally inhomogeneous warming in the tropical Ttropos, with a sensitivity coefficient of about −1.7 hPa K−1. This relationship explains a large fraction of observed and predicted changes in the tropical SLP. It is shown that in climate change model simulations the tropospheric land–sea warming contrast is the most significant structure in the regional Ttropos changes relative to the tropical mean changes. Since the land–sea warming contrast exists in the absence of any atmospheric circulation changes, it can be argued that the large-scale response of tropical SLP changes is to first order a response to the tropical land–sea warming contrast. Furthermore, as the land–sea warming contrast is mostly moisture dependent, the models predict a stronger warming and decreasing SLP in the drier regions from South America to Africa and a weaker warming and increasing SLP over the wetter Indo-Pacific warm pool region. This suggests an increase in the potential for deep convection conditions over the Atlantic sector and a decrease over the Indo-Pacific warm pool region in the future.
The Annual Peak in the SST Anomaly Spectrum
Publisher: American Meteorological Society
Date: 15-06-2008
Abstract: The manner in which monthly mean sea surface temperature anomalies (SSTAs) show enhanced variance at the annual period in the extratropics (an annual peak in the variance spectrum) is illustrated by observations and model simulations. A mechanism, related to the reemergence of winter SST anomalies, is proposed to explain the annual peak in SST spectrum. The idea is supported by the analysis of a hierarchy of models, including Intergovernmental Panel on Climate Change model simulations. The results of the model experiments further suggest that the annual peak is either weak or absent if decadal SST variability is forced by local air–sea interaction. However, if ocean subsurface temperature variability forces decadal SST variability, the annual peak is much stronger. Strong annual peaks may therefore be seen as an indication of ocean-forced decadal SST variability in the extratropics.
A simple model perturbed physics study of the simulated climate sensitivity uncertainty and its relation to control climate biases
Publisher: Springer Science and Business Media LLC
Date: 10-04-2015
Tropical Atmosphere–Ocean Interactions in a Conceptual Framework
Publisher: American Meteorological Society
Date: 02-2009
Abstract: Statistical analysis of observations (including atmospheric reanalysis and forced ocean model simulations) is used to address two questions: First, does an analogous mechanism to that of El Niño–Southern Oscillation (ENSO) exist in the equatorial Atlantic or Indian Ocean? Second, does the intrinsic variability in these basins matter for ENSO predictability? These questions are addressed by assessing the existence and strength of the Bjerknes and delayed negative feedbacks in each tropical basin, and by fitting conceptual recharge oscillator models, both with and without interactions among the basins. In the equatorial Atlantic the Bjerknes and delayed negative feedbacks exist, although weaker than in the Pacific. Equatorial Atlantic variability is well described by the recharge oscillator model, with an oscillatory mixed ocean dynamics–sea surface temperature (SST) mode present in boreal spring and summer. The dynamics of the tropical Indian Ocean, however, appear to be quite different: no recharge–discharge mechanism is found. Although a positive Bjerknes-like feedback from July to September is found, the role of heat content seems secondary. Results also show that Indian Ocean interaction with ENSO tends to d the ENSO oscillation and is responsible for a frequency shift to shorter periods. However, the retrospective forecast skill of the conceptual model is hardly improved by explicitly including Indian Ocean SST. The interaction between ENSO and the equatorial Atlantic variability is weaker. However, a feedback from the Atlantic on ENSO appears to exist, which slightly improves the retrospective forecast skill of the conceptual model.
The effects of remote SST forcings on ENSO dynamics, variability and diversity
Publisher: Springer Science and Business Media LLC
Date: 09-12-2016
Multidecadal changes in ENSO properties in the recharge oscillator conceptual model
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-21756
Abstract: & & & span& We use a simple conceptual recharge oscillator model for the tropical Pacific to identify multidecadal changes in El Ni& #241 o-Southern Oscillation (ENSO) statistics and dynamics during the observational record. The model, defined by only two variables, sea surface temperature (SST) and warm water volume (WWV), is fitted to the observations for the period 1901-2010. The variability of ENSO has increased during the 20& sup& th& /sup& century. The model simulates similar changes in variance of SST and WWV. The cross-correlation between SST and WWV also shows significant changes during the observational record. From the 1970s onwards, both observations and model output show that the SST drives WWV anomalies with a lead-time of 10 months and the WWV feedbacks onto the SST with a lead-time of about 8 months. The latter is reminiscent of a recharge-discharge mechanism of the upper ocean heat content. Before the 1970s only the impact of SST on WWV, through implied wind changes, is observed and is reproduced by the model. The periodicity of ENSO has also changed ENSO has become more frequent changing from a 7-yr periodicity in the beginning of 20& sup& th& /sup& century to a 5-yr periodicity in the recent decades. We find that the full recharge-discharge mechanism of the equatorial upper ocean heat content that characterizes the dynamics of the ReOsc model is only observed from the 1970s onwards and is likely to be a consequence of a stronger observed coupling between WWV and SST and of the leading role of the thermocline feedback. The& /span& & span& degrading quality in the observations for earlier periods can also partly explain the decadal changes in the ENSO interactions. We find that the Atlantic Multidecadal Variability and global warming can partly explain the observed and simulated multidecadal changes in ENSO properties.& /span& & &
An ensemble of AMIP simulations with prescribed land surface temperatures
Publisher: Copernicus GmbH
Date: 18-04-2018
DOI: 10.5194/GMD-2018-77
Abstract: Abstract. General circulation models (GCMs) are routinely run under Atmospheric Modelling Intercomparison Project (AMIP) conditions with prescribed sea surface temperatures (SSTs) and sea ice concentrations (SICs) from observations. These AMIP simulations are often used to evaluate the role of the land and/or atmosphere in causing the development of systematic errors in such GCMs. Extensions to the original AMIP experiment have also been developed to evaluate the response of the global climate to increased SSTs (prescribed) and carbon-dioxide (CO2) as part of the Cloud Feedback Model Intercomparison Project (CFMIP). None of these international modelling initiatives has undertaken a set of experiments where the land conditions are also prescribed, which is the focus of the work presented in this paper. Experiments are performed initially with freely varying land conditions (surface temperature and, soil temperature and mositure) under five different configurations (AMIP, AMIP with uniform 4 K added to SSTs, AMIP SST with quadrupled CO2, AMIP SST and quadrupled CO2 without the plant stomata response, and increasing the solar constant by 3.3 %). Then, the land surface temperatures from the free-land experiments are used to perform a set of “AMIP-prescribed land” (PL) simulations, which are evaluated against their free-land counterparts. The PL simulations agree well with the free-land experiments, which indicates that the land surface is prescribed in a way that is consistent with the original free-land configuration. Further experiments are also performed with different combinations of SSTs, CO2 concentrations, solar constant and land conditions. For ex le, SST and land conditions are used from the AMIP simulation with quadrupled CO2 in order to simulate the atmospheric response to increased CO2 concentrations without the surface temperature changing. The results of all these experiments have been made publicly available for further analysis. The main aims of this paper are to provide a description of the method used and an initial validation of these AMIP-prescribed land experiments.
Conceptual understanding of climate change with a globally resolved energy balance model
Publisher: Springer Science and Business Media LLC
Date: 18-03-2011
The fingerprint of global warming in the Tropical Pacific
Publisher: Springer Science and Business Media LLC
Date: 04-02-2016
The Monash Simple Climate Model Experiments (MSCM-DB v1.0): An interactive database of mean climate, climate change and scenario simulations
Publisher: Copernicus GmbH
Date: 08-2018
DOI: 10.5194/GMD-2018-143
Abstract: Abstract. This study introduces the Monash Simple Climate Model (MSCM) experiment database. The model simulations are based on the Globally Resolved Energy Balance (GREB) model. They provide a basis to study three different aspects of climate model simulations: (1) understanding the processes that control the mean climate, (2) the response of the climate to a doubling of the CO2 concentration, and (3) scenarios of external CO2 concentration and solar radiation forcings. A series of sensitivity experiments in which elements of the climate system are turned off in various combinations are used to address (1) and (2). This database currently provides more than 1,300 experiments and has an online web interface for fast analysis of the experiments and for open access to the data. We briefly outline the design of all experiments, give a discussion of some results, and put the findings into the context of previously published results from similar experiments. We briefly discuss the quality and limitations of the MSCM experiments and also give an outlook on possible further developments. The GREB model simulation of the mean climate processes is quite realistic, but does have uncertainties in the order of 20–30 %. The GREB model without flux corrections has a root mean square error in mean state of about 10 °C, which is larger than those of general circulation models (2 °C). However, the MSCM experiments show good agreement to previously published studies. Although GREB is a very simple model, it delivers good first-order estimates, is very fast, highly accessible, and can be used to quickly try many different sensitivity experiments or scenarios.
Erratum to: ENSO influence on the North Atlantic European climate: a non-linear and non-stationary approach
Publisher: Springer Science and Business Media LLC
Date: 08-04-2016
Simulated future changes in ENSO dynamics in the framework of the linear recharge oscillator model
Publisher: Springer Science and Business Media LLC
Date: 26-04-2019
Factors influencing the skill of synthesized satellite wind products in the tropical Pacific
Publisher: American Geophysical Union (AGU)
Date: 02-2017
DOI: 10.1002/2016JC012340
What Controls ENSO‐Amplitude Diversity in Climate Models?
Publisher: American Geophysical Union (AGU)
Date: 24-02-2018
DOI: 10.1002/2017GL076849
The Ocean’s Role in Continental Climate Variability and Change
Publisher: American Meteorological Society
Date: 15-09-2009
Abstract: A characteristic feature of global warming is the land–sea contrast, with stronger warming over land than over oceans. Recent studies find that this land–sea contrast also exists in equilibrium global change scenarios, and it is caused by differences in the availability of surface moisture over land and oceans. In this study it is illustrated that this land–sea contrast exists also on interannual time scales and that the ocean–land interaction is strongly asymmetric. The land surface temperature is more sensitive to the oceans than the oceans are to the land surface temperature, which is related to the processes causing the land–sea contrast in global warming scenarios. It suggests that the ocean’s natural variability and change is leading to variability and change with enhanced magnitudes over the continents, causing much of the longer-time-scale (decadal) global-scale continental climate variability. Model simulations illustrate that continental warming due to anthropogenic forcing (e.g., the warming at the end of the last century or future climate change scenarios) is mostly (80%–90%) indirectly forced by the contemporaneous ocean warming, not directly by local radiative forcing.
Land‐sea thermal contrast determines the trend of Walker circulation simulated in atmospheric general circulation models
Publisher: American Geophysical Union (AGU)
Date: 15-06-2017
DOI: 10.1002/2017GL073778
Multidecadal variability of ENSO in a recharge oscillator framework
Publisher: IOP Publishing
Date: 16-06-2022
Abstract: We use a conceptual recharge oscillator model to identify changes in El Niño and the Southern Oscillation (ENSO) statistics and dynamics during the observational record. The variability of ENSO has increased during the 20th century. The cross-correlation between sea surface temperature (SST) and warm water volume (WWV) has also changed during the observational record. From the 1970s onwards, the SST drives WWV anomalies with a lead-time of ten months and the WWV feedbacks onto the SST with a lead-time of eight months. This is reminiscent of a recharge-discharge mechanism of the upper ocean heat content. The full recharge-discharge mechanism is only observed from the 1970s onwards. This could be the result of the degradation of the quality of observations in the early part of the 20th century. However, it may also be a consequence of decadal changes in the coupling between WWV and SST. Additional analysis fitting the recharge oscillator model to the coupled state-of-the-art climate models indicates that ENSO properties show little decadal changes in the climate models. The disagreement in changes in ENSO properties between the reanalysis and the climate models can be due to errors in the available observational data or due to the models missing the low frequency variability and decadal wind trends. Longer and more reliable observational records would be required to validate our results.
Supplementary material to "An ensemble of AMIP simulations with prescribed land surface temperatures"
Publisher: Copernicus GmbH
Date: 18-04-2018
The role of local atmospheric forcing on the modulation of the ocean mixed layer depth in reanalyses and a coupled single column ocean model
Publisher: Springer Science and Business Media LLC
Date: 03-02-2016
Pantropical climate interactions.
Publisher: American Association for the Advancement of Science (AAAS)
Date: 03-2019
Abstract: The El Niño-Southern Oscillation (ENSO), which originates in the Pacific, is the strongest and most well-known mode of tropical climate variability. Its reach is global, and it can force climate variations of the tropical Atlantic and Indian Oceans by perturbing the global atmospheric circulation. Less appreciated is how the tropical Atlantic and Indian Oceans affect the Pacific. Especially noteworthy is the multidecadal Atlantic warming that began in the late 1990s, because recent research suggests that it has influenced Indo-Pacific climate, the character of the ENSO cycle, and the hiatus in global surface warming. Discovery of these pantropical interactions provides a pathway forward for improving predictions of climate variability in the current climate and for refining projections of future climate under different anthropogenic forcing scenarios.
Separating the Influences of Land Warming, the Direct CO2 Effect, the Plant Physiological Effect, and SST Warming on Regional Precipitation Changes
Publisher: American Geophysical Union (AGU)
Date: 23-01-2019
DOI: 10.1029/2018JD029423
Assessing ENSO Simulations and Predictions Using Adjoint Ocean State Estimation
Publisher: American Meteorological Society
Date: 15-11-2004
DOI: 10.1175/3211.1
Abstract: Simulations and seasonal forecasts of tropical Pacific SST and subsurface fields that are based on the global Consortium for Estimating the Circulation and Climate of the Ocean (ECCO) ocean-state estimation procedure are investigated. As compared to similar results from a traditional ENSO simulation and forecast procedure, the hindcast of the constrained ocean state is significantly closer to observed surface and subsurface conditions. The skill of the 12-month lead SST forecast in the equatorial Pacific is comparable in both approaches. The optimization appears to have better skill in the SST anomaly correlations, suggesting that the initial ocean conditions and forcing corrections calculated by the ocean-state estimation do have a positive impact on the predictive skill. However, the optimized forecast skill is currently limited by the low quality of the statistical atmosphere. Progress is expected from optimizing a coupled model over a longer time interval with the coupling statistics being part of the control vector.
Asymmetries in the ENSO phase space
Publisher: Springer Science and Business Media LLC
Date: 11-08-2022
DOI: 10.1007/S00382-022-06392-0
Abstract: El Niño Southern Oscillation (ENSO) dynamics are best described by the recharge oscillator model, in which the eastern tropical Pacific sea surface temperatures ( T ) and subsurface heat content (thermocline depth h ) have an out-of-phase relationship. This defines a 2-dimensional phase space diagram between T and h . In an idealized, stochastically forced d ed oscillator, the mean phase space diagram should be a perfectly symmetrical circle with a clockwise propagation over time. However, the observed phase space shows strong asymmetries. In this study we illustrate how the ENSO phase space can be used to discuss the phase-dependency of ENSO dynamics. A normalized spherical coordinate system allows the definition of phase-depending ENSO growth rates and phase transition speeds. Based on these we discuss the implications of the observed asymmetries with regards to the dynamics and predictability of ENSO with a particular focus on the variations in the growth rate and coupling of ENSO along the oscillation cycle. Using linear and non-linear recharge oscillator models we will show how dynamics and noise are driving ENSO at different phases of the ENSO cycles. The results illustrate that the ENSO cycle with positive phase transitions is present in all phases but has strong variations in its strength. Much of these variations result from presenting the ENSO phase space with estimates of h based on the iso-thermal depth, that is not ideal as it is not out-of-phase with T . Future work should address how h can be estimated better, including aspects such as the vertical temperature gradients and the meridional or zonal range. We further illustrated that a non-linear growth rate of T can explain most of the observed non-linear phase space characteristics.
Asymmetries in the ENSO Phase Space
Publisher: Research Square Platform LLC
Date: 22-03-2022
DOI: 10.21203/RS.3.RS-1456774/V1
Abstract: El Niño Southern Oscillation (ENSO) dynamics are best described by the recharge oscillator model, in which the eastern tropical Pacific sea surface temperatures ( T ) and subsurface heat content (thermocline depth h ) have an out-of-phase relationship. This defines a 2dimensional phase space diagram between T and h . In an idealized, stochastically forced d ed oscillator, the phase space diagram should be a perfectly symmetrical circle with a clockwise propagation over time. However, the observed phase space shows strong asymmetries. In this study we illustrate how the ENSO phase space can be used to discuss the phase-dependency of ENSO dynamics. A normalized spherical coordinate system allows the definition of phase-depending ENSO growth rates and phase transition speeds. Based on these we discuss the implications of the observed asymmetries with regards to the dynamics and predictability of ENSO with a particular focus on the variations in the growth rate and coupling of ENSO along the oscillation cycle. Using linear and non-linear recharge oscillator models we will show how dynamics and noise are driving ENSO at different phases of the ENSO cycles. The results illustrate that the ENSO cycle with positive phase transitions is present in all phases but has strong variations in its strength. Much of these variations result from presenting the ENSO phase space with estimates of h based on the iso-thermal depth, which is not ideal as it is not out-of-phase with T . We further illustrated that a non-linear growth rate of T can explain most of the observed non-linear phase space characteristics.
Revisiting ENSO Atmospheric Teleconnections and Challenges
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-16656
Abstract: & & The warming of the equatorial Pacific associated with the El Ni& #241 o& #8211 Southern Oscillation (ENSO) causes profound impacts on rainfall and temperature in the tropics and extratropics. El Ni& #241 o drives changes in the Walker and Hadley circulations, warms the tropics and affects the neighboring ocean basins, favoring a short-term rise in global temperatures. We will present an overview of the atmospheric teleconnections driven by ENSO and its ersity focusing on the impacts over land and remote ocean basins. During El Ni& #241 o, dry conditions are generally observed in the Maritime Continent, northern South America, South Asia and South Africa, while wet weather typically occurs in southwestern North America, western Antarctica, and east Africa. Global effects during La Ni& #241 a are overall the opposite to El Ni& #241 o, however this assumption is not true for all regions. ENSO atmospheric teleconnections are non-linear in part due to different locations of the anomalous equatorial warming (Eastern versus Central Pacific events) superimposed on the Pacific mean state, as well as interactions with the annual cycle, off-equatorial regions, remote ocean basins, and other modes of climate variability. Adding to this complex behavior, ENSO teleconnections are non-stationary either due to deterministic low-frequency modulations or stochastic variability, the latter being a factor generally overlooked in the literature.& As the world warms in response to greenhouse gas forcing, ENSO atmospheric teleconnections are expected to change, despite large uncertainties in ENSO projections. We will discuss the limitations of climate models in representing realistic teleconnections from the tropical Pacific to remote regions and some of the challenges for future projections.& &
Interdecadal interactions between the tropics and midlatitudes in the Pacific Basin
Publisher: American Geophysical Union (AGU)
Date: 03-1999
DOI: 10.1029/1999GL900042
The influence of global sea surface temperature variability on the large-scale land surface temperature
Publisher: Springer Science and Business Media LLC
Date: 10-2014
The slab ocean El Niño
Publisher: American Geophysical Union (AGU)
Date: 10-2010
DOI: 10.1029/2010GL044888
El Niño and La Niña amplitude asymmetry caused by atmospheric feedbacks
Publisher: American Geophysical Union (AGU)
Date: 09-2010
DOI: 10.1029/2010GL044444
Walker Circulation controls ENSO Atmospheric Feedbacks in Uncoupled and Coupled Climate Model Simulations
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-8835
Abstract: & & & span& & span& Many climate models strongly underestimate the two most important atmospheric feedbacks operating in El Ni& #241 o/Southern Oscillation (ENSO), the positive ( lifying) zonal surface wind feedback and negative (d ing) surface-heat flux feedback (hereafter ENSO atmospheric feedbacks, EAF), h ering realistic representation of ENSO dynamics in these models. Here we show that the atmospheric components of climate models participating in the 5& /span& & /span& & sup& & span& & span& th& /span& & /span& & /sup& & span& & span& phase of the Coupled Model Intercomparison Project (CMIP5) when forced by observed sea surface temperatures (SST), already underestimate EAF on average by 23%, but less than their coupled counterparts (on average by 54%). There is a pronounced tendency of atmosphere models to simulate stronger EAF, when they exhibit a stronger mean deep convection and enhanced cloud cover over the western equatorial Pacific (WEP), indicative of a stronger rising branch of the Pacific Walker Circulation (PWC). Further, differences in the mean deep convection over the WEP between the coupled and uncoupled models explain a large part of the differences in EAF, with the deep convection in the coupled models strongly depending on the equatorial Pacific SST bias. Experiments with a single atmosphere model support the relation between the equatorial Pacific atmospheric mean state, the SST bias and the EAF. An implemented cold SST bias in the observed SST forcing weakens deep convection and reduces cloud cover in the rising branch of the PWC, causing weaker EAF. A warm SST bias has the opposite effect. Our results elucidate how biases in the mean state of the PWC and equatorial SST h er a realistic simulation of the EAF. & /span& & /span& & &
Correction to “El Niño and La Niña amplitude asymmetry caused by atmospheric feedbacks”
Publisher: American Geophysical Union (AGU)
Date: 2011
DOI: 10.1029/2010GL045541
Wind Spatial Structure Triggers ENSO’s Oceanic Warm Water Volume Changes
Publisher: American Meteorological Society
Date: 03-2021
Abstract: This study demonstrates that the generalization that strong anomalous equatorial Pacific westerly (easterly) winds during El Niño (La Niña) events display strong adjusted warm water volume (WWV) discharges (recharges) is often incorrect. Using ocean model simulations, we categorize the oceanic adjusted responses to strong anomalous equatorial winds into two categories: (i) transitioning (consistent with the above generalization) and (ii) neutral adjusted responses (with negligible WWV recharge and discharge). During the 1980–2016 period only 47% of strong anomalous equatorial winds are followed by transitioning adjusted responses, while the remaining are followed by neutral adjusted responses. Moreover, 55% (only 30%) of the strongest winds lead to transitioning adjusted responses during the pre-2000 (post-2000) period in agreement with the previously reported post-2000 decline of WWV lead time to El Niño–Southern Oscillation (ENSO) events. The prominent neutral adjusted WWV response is shown to be largely excited by anomalous wind stress forcing with a weaker curl (on average consistent with a higher ratio of off-equatorial to equatorial wind events) and weaker Rossby wave projection than the transitioning adjusted response. We also identify a prominent ENSO phase asymmetry where strong anomalous equatorial westerly winds (i.e., El Niño events) are roughly 1.6 times more likely to strongly discharge WWV than strong anomalous equatorial easterly winds (i.e., La Niña events) are to strongly recharge WWV. This ENSO phase asymmetry may be added to the list of mechanisms proposed to explain why El Niño events have a stronger tendency to be followed by La Niña events than vice versa.
Analysis of the non-linearity in the pattern and time evolution of El Niño southern oscillation
Publisher: Springer Science and Business Media LLC
Date: 09-08-2012
Evaluating EOF modes against a stochastic null hypothesis
Publisher: Springer Science and Business Media LLC
Date: 18-10-2006
The Role of Indian Ocean Sea Surface Temperature in Forcing East African Rainfall Anomalies during December–January 1997/98
Publisher: American Meteorological Society
Date: 12-1999
Analysis of observed and simulated SST spectra in the midlatitudes
Publisher: Springer Science and Business Media LLC
Date: 07-2002
Origins of the midlatitude Pacific decadal variability
Publisher: American Geophysical Union (AGU)
Date: 15-05-1999
DOI: 10.1029/1999GL900278
The eastward shift of the Walker Circulation in response to global warming and its relationship to ENSO variability
Publisher: Springer Science and Business Media LLC
Date: 11-03-2014
GREB-ISM v1.0: A coupled ice sheet model for the Globally Resolved Energy Balance model for global simulations on timescales of 100 kyr
Publisher: Copernicus GmbH
Date: 10-05-2022
Abstract: Abstract. We introduce a newly developed global ice sheet model coupled to the Globally Resolved Energy Balance (GREB) climate model for the simulation of global ice sheet evolution on timescales of 100 kyr or longer (GREB-ISM v1.0). Ice sheets and ice shelves are simulated on a global grid, fully interacting with the climate simulation of surface temperature, precipitation, albedo, land–sea mask, topography and sea level. Thus, it is a fully coupled atmosphere, ocean, land and ice sheet model. We test the model in ice sheet stand-alone and fully coupled simulations. The ice sheet model dynamics behave similarly to other hybrid SIA (shallow ice approximation) and SSA (shallow shelf approximation) models, but the West Antarctic Ice Sheet accumulates too much ice using present-day boundary conditions. The coupled model simulations produce global equilibrium ice sheet volumes and calving rates like those observed for present-day boundary conditions. We designed a series of idealized experiments driven by oscillating solar radiation forcing on periods of 20, 50 and 100 kyr in the Northern Hemisphere. These simulations show clear interactions between the climate system and ice sheets, resulting in slow buildup and fast decay of ice-covered areas and global ice volume. The results also show that Northern Hemisphere ice sheets respond more strongly to timescales longer than 100 kyr. The coupling to the atmosphere and sea level leads to climate interactions between the Northern and Southern Hemispheres. The model can run global simulations of 100 kyr d−1 on a desktop computer, allowing the simulation of the whole Quaternary period (2.6 Myr) within 1 month.
Is the Indian Ocean SST variability a homogeneous diffusion process?
Publisher: Springer Science and Business Media LLC
Date: 08-01-2009
Reduced Complexity Model Intercomparison Project Phase 1: introduction and evaluation of global-mean temperature response
Publisher: Copernicus GmbH
Date: 31-10-2020
Abstract: Abstract. Reduced-complexity climate models (RCMs) are critical in the policy and decision making space, and are directly used within multiple Intergovernmental Panel on Climate Change (IPCC) reports to complement the results of more comprehensive Earth system models. To date, evaluation of RCMs has been limited to a few independent studies. Here we introduce a systematic evaluation of RCMs in the form of the Reduced Complexity Model Intercomparison Project (RCMIP). We expect RCMIP will extend over multiple phases, with Phase 1 being the first. In Phase 1, we focus on the RCMs' global-mean temperature responses, comparing them to observations, exploring the extent to which they emulate more complex models and considering how the relationship between temperature and cumulative emissions of CO2 varies across the RCMs. Our work uses experiments which mirror those found in the Coupled Model Intercomparison Project (CMIP), which focuses on complex Earth system and atmosphere–ocean general circulation models. Using both scenario-based and idealised experiments, we examine RCMs' global-mean temperature response under a range of forcings. We find that the RCMs can all reproduce the approximately 1 ∘C of warming since pre-industrial times, with varying representations of natural variability, volcanic eruptions and aerosols. We also find that RCMs can emulate the global-mean temperature response of CMIP models to within a root-mean-square error of 0.2 ∘C over a range of experiments. Furthermore, we find that, for the Representative Concentration Pathway (RCP) and Shared Socioeconomic Pathway (SSP)-based scenario pairs that share the same IPCC Fifth Assessment Report (AR5)-consistent stratospheric-adjusted radiative forcing, the RCMs indicate higher effective radiative forcings for the SSP-based scenarios and correspondingly higher temperatures when run with the same climate settings. In our idealised setup of RCMs with a climate sensitivity of 3 ∘C, the difference for the ssp585–rcp85 pair by 2100 is around 0.23∘C(±0.12 ∘C) due to a difference in effective radiative forcings between the two scenarios. Phase 1 demonstrates the utility of RCMIP's open-source infrastructure, paving the way for further phases of RCMIP to build on the research presented here and deepen our understanding of RCMs.
Impacts of the tropical Indian and Atlantic Oceans on ENSO
Publisher: American Geophysical Union (AGU)
Date: 06-2006
DOI: 10.1029/2006GL025871
Reduced complexity model intercomparison project phase 1: Protocol, results and initial observations
Publisher: Copernicus GmbH
Date: 21-01-2020
DOI: 10.5194/GMD-2019-375
Abstract: Abstract. Here we present results from the first phase of the Reduced Complexity Model Intercomparison Project (RCMIP). RCMIP is a systematic examination of reduced complexity climate models (RCMs), which are used to complement and extend the insights from more complex Earth System Models (ESMs), in particular those participating in the Sixth Coupled Model Intercomparison Project (CMIP6). In Phase 1 of RCMIP, with 14 participating models namely ACC2, AR5IR (2 and 3 box versions), CICERO-SCM, ESCIMO, FaIR, GIR, GREB, Hector, Held et al. two layer model, MAGICC, MCE, OSCAR and WASP, we highlight the structural differences across various RCMs and show that RCMs are capable of reproducing global-mean surface air temperature (GSAT) changes of ESMs and historical observations. We find that some RCMs are capable of emulating the GSAT response of CMIP6 models to within a root-mean square error of 0.2 °C (of the same order of magnitude as ESM internal variability) over a range of scenarios. Running the same model configurations for both RCP and SSP scenarios, we see that the SSPs exhibit higher effective radiative forcing throughout the second half of the 21st Century. Comparing our results to the difference between CMIP5 and CMIP6 output, we find that the change in scenario explains approximately 46 % of the increase in higher end projected warming between CMIP5 and CMIP6. This suggests that changes in ESMs from CMIP5 to CMIP6 explain the rest of the increase, hence the higher climate sensitivities of available CMIP6 models may not be having as large an impact on GSAT projections as first anticipated. A second phase of RCMIP will complement RCMIP Phase 1 by exploring probabilistic results and emulation in more depth to provide results available for the IPCC's Sixth Assessment Report author teams.
The role of ocean dynamics in producing decadal climate variability in the North Pacific
Publisher: Springer Science and Business Media LLC
Date: 11-2001
Interannual to Decadal Variability in the Tropical Atlantic
Publisher: American Meteorological Society
Date: 02-2000
The seasonally changing cloud feedbacks contribution to the ENSO seasonal phase-locking
Publisher: Springer Science and Business Media LLC
Date: 18-02-2016
ENSO Atmospheric Teleconnections and Their Response to Greenhouse Gas Forcing
Publisher: American Geophysical Union (AGU)
Date: 17-02-2018
DOI: 10.1002/2017RG000568
May common model biases reduce CMIP5’s ability to simulate the recent Pacific La Niña-like cooling?
Publisher: Springer Science and Business Media LLC
Date: 18-04-2018
A Hydrological Cycle Model for the Globally Resolved Energy Balance Model (GREB) v1.0
Publisher: Copernicus GmbH
Date: 18-06-2018
DOI: 10.5194/GMD-2018-131
Abstract: Abstract. In this study, we describe the development of the hydrological cycle for the Globally Resolved Energy Balance (GREB) model. Starting from a very simple zero order hydrological cycle model included in the GREB model, we develop three new models: precipitation, evaporation and horizontal transport of water vapour. Precipitation is modelled based on the actual simulated specific and relative humidity in GREB and the prescribed boundary condition of vertical velocity. The evaporation bulk formula is slightly refined by considering differences in the sensitivity to winds between land and oceans, and by improving the estimates of the wind magnitudes. Horizontal transport of water vapour is improved by approximating moisture convergence by vertical velocity. The new parameterisations are fitted against observations (GPCP) and reanalysis data sets (ERA-Interim). The new hydrological cycle is evaluated against CMIP model simulation, reduction in correction terms and by three different sensitivity experiments (Annual Cycle, El Nino Southern Oscillation and Climate Change). The skill of the hydrological cycle in the GREB model is now within the range of more complex CMIP5 CGCMs and capable of simulating key features of the climate system within the range of uncertainty of CMIP5 model simulations. The results illustrate that the new GREB model’s hydrological cycle is a useful model to study the climate’s hydrological response to external forcings and also to study inter-model differences or biases.
Analysis of the simulated feedbacks on large-scale ice sheets from ice-sheet climate interactions
Publisher: Copernicus GmbH
Date: 15-03-2023
DOI: 10.5194/EGUSPHERE-2023-370
Abstract: Abstract. In study presented here we focus on the large climate-ice sheet feedbacks on global scales on time scales of 100,000 yrs. We conducted a series of idealised sensitivity experiments under CO2 and solar radiation reduction scenarios with the Globally Resolved Energy Balance - Ice Sheet Model v1.0 (GREB-ISM v1.0), to study the characteristics of five climate-ice sheet feedbacks, including albedo, snowfall, ice latent heat, topography and sea level feedbacks. We analysed the relative importance of each of these feedbacks on the ice sheet growth and on the climate system (surface temperature). The results indicate that the inclusion of ice sheets will delay the response to the external forcing and facilitate the climate cooling in the high latitude and altitude areas in the Northern Hemisphere, but also causes a small amount of warming elsewhere, due to the blocking of atmospheric heat transport. As for in idual feedbacks, the albedo feedback is the most dominant positive feedback in favour of ice sheet build-up and cooler climates, whereas snowfall feedback is the greatest negative feedback that reduces the growth of ice sheets. The large ice latent heat required to melt ice allows to maintain ice sheets from one cold seasons to the next and therefore provides a positive feedback for ice sheet growth. The ice sheets impact on the topography is also a positive feedback but with smaller impact than the albedo feedback. The sea level change influences ice sheets by shifting their location, in particular allowing ice sheets growth in the Arctic Ocean, while reducing it over central north Asia.
An ensemble of AMIP simulations with prescribed land surface temperatures
Publisher: Copernicus GmbH
Date: 26-09-2018
Abstract: Abstract. General circulation models (GCMs) are routinely run under Atmospheric Modelling Intercomparison Project (AMIP) conditions with prescribed sea surface temperatures (SSTs) and sea ice concentrations (SICs) from observations. These AMIP simulations are often used to evaluate the role of the land and/or atmosphere in causing the development of systematic errors in such GCMs. Extensions to the original AMIP experiment have also been developed to evaluate the response of the global climate to increased SSTs (prescribed) and carbon dioxide (CO2) as part of the Cloud Feedback Model Intercomparison Project (CFMIP). None of these international modelling initiatives has undertaken a set of experiments where the land conditions are also prescribed, which is the focus of the work presented in this paper. Experiments are performed initially with freely varying land conditions (surface temperature, and soil temperature and moisture) under five different configurations (AMIP, AMIP with uniform 4 K added to SSTs, AMIP SST with quadrupled CO2, AMIP SST and quadrupled CO2 without the plant stomata response, and increasing the solar constant by 3.3 %). Then, the land surface temperatures from the free land experiments are used to perform a set of “AMIP prescribed land” (PL) simulations, which are evaluated against their free land counterparts. The PL simulations agree well with the free land experiments, which indicates that the land surface is prescribed in a way that is consistent with the original free land configuration. Further experiments are also performed with different combinations of SSTs, CO2 concentrations, solar constant and land conditions. For ex le, SST and land conditions are used from the AMIP simulation with quadrupled CO2 in order to simulate the atmospheric response to increased CO2 concentrations without the surface temperature changing. The results of all these experiments have been made publicly available for further analysis. The main aims of this paper are to provide a description of the method used and an initial validation of these AMIP prescribed land experiments.
MEETING SUMMARIES
Publisher: American Meteorological Society
Date: 11-2015
Analysis of the Model Climate Sensitivity Spread Forced by Mean Sea Surface Temperature Biases
Publisher: American Meteorological Society
Date: 09-05-2012
DOI: 10.1175/JCLI-D-11-00600.1
Abstract: Uncertainties in the numerical realization of the physical climate system in coarse-resolution climate models in the Coupled Model Intercomparison Project phase 3 (CMIP3) cause large spread in the global mean and regional response litude to a given anthropogenic forcing scenario, and they cause the climate models to have mean state climates different from the observed and different from each other. In a series of sensitivity simulations with an atmospheric general circulation model coupled to a Slab Ocean Model, the role of differences in the control mean sea surface temperature (SST) in simulating the global mean and regional response litude is explored. The model simulations are forced into the control mean state SST of 24 CMIP3 climate models, and 2xCO2 forcing experiments are started from the different control states. The differences in the SST mean state cause large differences in other climate variables, but they do not reproduce most of the large spread in the mean state climate over land and ice-covered regions found in the CMIP3 model simulations. The spread in the mean SST climatology leads to a spread in the global mean and regional response litude of about 10%, which is about half as much as the spread in the response of the CMIP3 climate models and is therefore of considerable size. Since the SST climatology biases are only a small part of the models’ mean state climate biases, it is likely that the climate model’s mean state climate biases are accounting for a large part of the model’s climate sensitivity spread.
Analysis of the Slab Ocean El Nino atmospheric feedbacks in observed and simulated ENSO dynamics
Publisher: Springer Science and Business Media LLC
Date: 04-02-2014
Increased frequency of extreme La Niña events under greenhouse warming
Publisher: Springer Science and Business Media LLC
Date: 26-01-2015
DOI: 10.1038/NCLIMATE2492
Atmosphere-only GCM (ACCESS1.0) simulations with prescribed land surface temperatures
Publisher: Copernicus GmbH
Date: 07-06-2016
Abstract: Abstract. General circulation models (GCMs) are valuable tools for understanding how the global ocean–atmosphere–land surface system interacts and are routinely evaluated relative to observational data sets. Conversely, observational data sets can also be used to constrain GCMs in order to identify systematic errors in their simulated climates. One such ex le is to prescribe sea surface temperatures (SSTs) such that 70 % of the Earth's surface temperature field is observationally constrained (known as an Atmospheric Model Intercomparison Project, AMIP, simulation). Nevertheless, in such simulations, land surface temperatures are typically allowed to vary freely, and therefore any errors that develop over the land may affect the global circulation. In this study therefore, a method for prescribing the land surface temperatures within a GCM (the Australian Community Climate and Earth System Simulator, ACCESS) is presented. Simulations with this prescribed land surface temperature model produce a mean climate state that is comparable to a simulation with freely varying land temperatures for ex le, the diurnal cycle of tropical convection is maintained. The model is then developed further to incorporate a selection of “proof of concept” sensitivity experiments where the land surface temperatures are changed globally and regionally. The resulting changes to the global circulation in these sensitivity experiments are found to be consistent with other idealized model experiments described in the wider scientific literature. Finally, a list of other potential applications is described at the end of the study to highlight the usefulness of such a model to the scientific community.
Ocean mixed layer depth: A subsurface proxy of ocean‐atmosphere variability
Publisher: American Geophysical Union (AGU)
Date: 07-2006
DOI: 10.1029/2003JC002157
The leading modes of decadal SST variability in the Southern Ocean in CMIP5 simulations
Publisher: Springer Science and Business Media LLC
Date: 21-12-2015
El Nino-Southern Oscillation complexity
Publisher: Springer Science and Business Media LLC
Date: 07-2018
DOI: 10.1038/S41586-018-0252-6
Abstract: El Niño events are characterized by surface warming of the tropical Pacific Ocean and weakening of equatorial trade winds that occur every few years. Such conditions are accompanied by changes in atmospheric and oceanic circulation, affecting global climate, marine and terrestrial ecosystems, fisheries and human activities. The alternation of warm El Niño and cold La Niña conditions, referred to as the El Niño-Southern Oscillation (ENSO), represents the strongest year-to-year fluctuation of the global climate system. Here we provide a synopsis of our current understanding of the spatio-temporal complexity of this important climate mode and its influence on the Earth system.
An evaluation of ENSO dynamics in CMIP simulations in the framework of the recharge oscillator model
Publisher: Springer Science and Business Media LLC
Date: 18-11-2017
Analysis of the Nonlinearity of El Niño–Southern Oscillation Teleconnections*
Publisher: American Meteorological Society
Date: 07-08-2014
DOI: 10.1175/JCLI-D-13-00757.1
Abstract: El Niño–Southern Oscillation (ENSO) has significant variations and nonlinearities in its pattern and strength. ENSO events vary in their position along the equator, with some located in the central Pacific (CP) and others in the east Pacific (EP). To study how these variations are reflected in global ENSO teleconnections, both observations and idealized atmospheric general circulation model (AGCM) simulations are analyzed. Clear nonlinearities exist in observed teleconnections of sea level pressure (SLP) and precipitation. However, it is difficult to distinguish if these are caused by the different signs, strengths, or spatial patterns of events (strong El Niño events mostly being EP events and strong La Niña events mostly being CP events) or by combinations of these. Therefore, sensitivity experiments are performed with an AGCM forced with idealized EP and CP ENSO sea surface temperature (SST) patterns with varying signs and strengths. The response is generally stronger for warm events than for cold events and the teleconnection patterns vary with changing SST anomaly patterns. EP events show stronger nonlinearities than CP events. The nonlinear responses to ENSO events can be explained as a combination of nonlinear responses to a linear ENSO (fixed pattern but varying signs and strengths) and a linear response to a nonlinear ENSO (varying patterns). Any observed event is a combination of these aspects. While in most tropical regions these add up, leading to stronger nonlinear responses than expected from the single components, in some regions they cancel each other, resulting in little overall nonlinearity. This leads to strong regional differences in ENSO teleconnections.
Strengthening atmospheric circulation and trade winds slowed tropical Pacific surface warming
Publisher: Springer Science and Business Media LLC
Date: 12-07-2023
DOI: 10.1038/S43247-023-00912-4
Abstract: The globally averaged sea-surface temperature (SST) has steadily increased in the last four decades, consistent with the rising atmospheric greenhouse gas concentrations. Parts of the tropical Pacific exhibited less warming than the global average or even cooling, which is not captured by state-of-the-art climate models and the reasons are poorly understood. Here we show that the last four decades featured a strengthening atmospheric circulation and stronger trade winds over the tropical Pacific, which counteracted externally-forced SST warming. Climate models do not simulate the trends in the atmospheric circulation irrespective of whether an external forcing is applied or not and model bias is the likely reason. This study raises questions about model-based tropical Pacific climate change projections and emphasizes the need to enhance understanding of tropical Pacific climate dynamics and response to external forcing in order to project with confidence future climate changes in the tropical Pacific sector and beyond.
Mean-state dependence of ENSO atmospheric feedbacks in climate models
Publisher: Springer Science and Business Media LLC
Date: 15-07-2017
Impact of the Pacific mean SST bias to the Atlantic-Pacific teleconnection
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-7407
Abstract: & & & span& A robust eastern tropical Pacific surface temperature cooling trend along with the strengthening of Pacific trade wind is evident across different observations since late 1990s, which is considered as a pronounced contributor to the slowdown in global surface warming. However, most CMIP5 historical simulations failed to reproduce this La Ni& /span& & #241 & span& a-like change. Previous studies have attributed this discrepancy between the multi-model simulations and the observations to the underrepresentation of Pacific low-frequency variability together with the misrepresentation of inter-basin forcing response. The underlying reasons remain unclear. Here, we investigate a hypothesis that common Pacific mean SST bias may diminish the Pacific-Atlantic atmospheric teleconnection and further contribute to the underestimated eastern Pacific cooling. Model results suggest that the CMIP5-like Pacific bias acts to reduce the Atlantic heating response by strengthening the atmospheric stability over the Atlantic region and therefore weaken the trans-basin variability. In addition, & /span& the Pacific bias simulation with a strong SST cold tongue substantially undermined the positive zonal wind feedback, which also contributes to the underestimated Pacific cooling response. Future efforts aim at reducing the model mean state biases may significantly help to improve the simulation skills of the trans-basin teleconnection, Pacific decadal variability, and the associated Pacific dynamics.& & & & & & &
Paving the way for industry 4.0 maturity of construction enterprises: a state of the art review
Publisher: Emerald
Date: 11-07-2022
DOI: 10.1108/ECAM-11-2021-1001
Abstract: Industry 4.0 is characterised by the exponential pace of technological innovations compelling organisations to transform or be displaced. Industry 4.0 transformation of construction enterprises lacks systematic guidance and notable earlier studies have utilised maturity models to map transformation of enterprises. This paper proposes a conceptual maturity model for construction enterprises for business scenarios leading to Industry 4.0. The requirements for designing maturity models, including comparison with existing models and scientifically documenting the design process, make Systematic Literature Reviews (SLR) appropriate. Two systematic literature reviews (SLRs) are conducted to shortlist a total of 95 papers, which are subjected to subsequent content analysis. The first SLR identifies the following process categories as critical levers of industry 4.0 maturity data management, people and culture, leadership and strategy, collaboration and communication, automation, innovation and change management. The second SLR ascertains that the existing maturity models in construction literature do not adequately correspond to Industry 4.0 business scenarios with limited emphasis on data management, automation, change management and innovation. The findings are assimilated to propose a conceptual Smart Modern Construction Enterprise Maturity Model (SMCeMM). The paper systematises the transformation of construction enterprises in Industry 4.0 and leads to state-of-the-art development of Industry 4.0 and maturity model research in construction. The proposed conceptual model addressed both the demands of the construction industry as well as what is required to navigate Industry 4.0 better.
The Monash Simple Climate Model experiments (MSCM-DB v1.0): an interactive database of mean climate, climate change, and scenario simulations
Publisher: Copernicus GmbH
Date: 03-06-2019
Abstract: Abstract. This study introduces the Monash Simple Climate Model (MSCM) experiment database. The simulations are based on the Globally Resolved Energy Balance (GREB) model to study three different aspects of climate model simulations: (1) understanding processes that control the mean climate, (2) the response of the climate to a doubling of the CO2 concentration, and (3) scenarios of external forcing (CO2 concentration and solar radiation). A series of sensitivity experiments in which elements of the climate system are turned off in various combinations are used to address (1) and (2). This database currently provides more than 1300 experiments and has an online web interface for fast analysis and free access to the data. We briefly outline the design of all experiments, give a discussion of some results, put the findings into the context of previously published results from similar experiments, discuss the quality and limitations of the MSCM experiments, and also give an outlook on possible further developments. The GREB model simulation is quite realistic, but the model without flux corrections has a root mean square error in the mean state of the surface temperature of about 10 ∘C, which is larger than those of general circulation models (2 ∘C). It needs to be noted here that the GREB model does not simulate circulation changes or changes in cloud cover (feedbacks). However, the MSCM experiments show good agreement to previously published studies. Although GREB is a very simple model, it delivers good first-order estimates, is very fast, highly accessible, and can be used to quickly try many different sensitivity experiments or scenarios. It builds a basis on which conceptual ideas can be tested to first order and it provides a null hypothesis for understanding complex climate interactions in the context of response to external forcing or interactions in the climate subsystems.
Comments on “The Relationship between Land–Ocean Surface Temperature Contrast and Radiative Forcing”
Publisher: American Meteorological Society
Date: 05-2012
DOI: 10.1175/JCLI-D-11-00476.1
Abstract: In a recent article, Dommenget discussed the role of sea surface temperature variability for continental climate variability and change. Lambert et al. comment on Dommenget’s article in their article several times, arguing that the sensitivity experiment in Dommenget, in which the SST response to surface land temperature changes are discussed, is inconsistent with their and other previously published studies. In this comment, the results of Dommenget’s sensitivity experiments are discussed in more detail and the experiments are extended for longer response times. It is shown that the discussion of how the oceans’ response to land forcing is time-scale dependent, with a very weak response to land forcing on interannual time scales, as discussed in Dommenget, and that it has about a twice as strong of a near-equilibrium response to land forcing on time scales longer than 100 yr. The asymmetric land–sea interaction, with the ocean forcing the land much more strongly than the land forces the oceans, as discussed in Dommenget, is confirmed by this study.
ENSO dynamics and diversity resulting from the recharge oscillator interacting with the slab ocean
Publisher: Springer Science and Business Media LLC
Date: 28-05-2015
Supplementary material to "The Monash Simple Climate Model Experiments (MSCM-DB v1.0): An interactive database of mean climate, climate change and scenario simulations"
Publisher: Copernicus GmbH
Date: 08-2018
ENSO phase space dynamics with an improved estimate of the thermocline depth
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-2477
Abstract: The recharge oscillator model of the El Ni& #241 o Southern Oscillation (ENSO) describes the ENSO dynamics as an interaction and oscillation between the eastern tropical Pacific sea surface temperatures (T) and subsurface heat content (thermocline depth h), describing a cycle of ENSO phases. h is often approximated on the basis of the depth of the 20oC isotherm (Z20). In this study we will address how the estimation of h affects the representation of ENSO dynamics. We will compare the ENSO phase space with h estimated based on Z20 and based on the maximum gradient in the temperature profile (Zmxg). The results illustrate that the ENSO phase space is much closer to the idealised recharge oscillator model if based on Zmxg than if based on Z20. Using linear and non-linear recharge oscillator models fitted to the observed data illustrates that the Z20 estimate leads to artificial phase dependent structures in the ENSO phase space, which result from an in-phase correlation between h and T. Based on the Zmxg estimate the ENSO phase space diagram show very clear non-linear aspects in growth rates and phase speeds. Based on this estimate we can describe the ENSO cycle dynamics as a non-linear cycle that grows during the recharge and El Nino state, and decays during the La Nina states. The most extreme ENSO states are during the El Nino and discharge states, while the La Nina and recharge states do not have extreme states. It further has faster phase speeds after the El Nino state and slower phase speeds during and after the La Nina states. The analysis suggests that the ENSO phase speed is significantly positive in all phases, suggesting that ENSO is indeed a cycle. However, the phase speeds are closest to zero during and after the La Nina state, indicating that the ENSO cycle is most likely to stall in these states.
A Cautionary Note on the Interpretation of EOFs
Publisher: American Meteorological Society
Date: 2002
A Caveat Note on Tuning in the Development of Coupled Climate Models
Publisher: American Geophysical Union (AGU)
Date: 2018
DOI: 10.1002/2017MS000947
The weakening of the tropical circulation is caused by the lifting of the tropopause height
Publisher: Springer Science and Business Media LLC
Date: 09-08-2023
DOI: 10.1007/S00382-023-06909-1
Abstract: In this study we analyse the physical processes causing the weakening of the tropical circulation in the Coupled Model Intercomparison Project 6 (CMIP6). We apply a diagnostic model for the large-scale tropical circulation (vertical motion) based on the moist static energy for the first baroclinic mode (MSEB) and evaluate the sensitivity of the tropical circulation changes to the changes in advection of moisture and heat, the net radiation, the moist static stability, the baroclinic mode, and to the height of the tropopause. Based on the CMIP6 model simulations we find that the tropical circulation weakens by about 10-15% over the twenty-first century. The analysis of the MSEB model suggests that the primary cause for this weakening of the tropical circulation is the lifting of the tropopause height. This effect is fairly uniform throughout the tropics and present in all model simulations. The tropopause height increase shifts the first baroclinic mode away from lower levels with unstable air masses into high levels of the troposphere where stable air masses lead to a stabilisation of the large-scale circulation. Other factors such as changes in the advection of moisture and heat, increased net heating or increased instability of the lower tropospheric gross moist stability do have strong regional differences, and mostly increase tropical circulations, counteracting the weakening caused by the lifting of the tropopause.
Asymmetries in the ENSO phase space
Publisher: Copernicus GmbH
Date: 27-03-2022
DOI: 10.5194/EGUSPHERE-EGU22-3263
Abstract: & & El Ni& #241 o Southern Oscillation (ENSO) dynamics are best described by the recharge oscillator model, in which the eastern tropical Pacific sea surface temperatures (& strong& & em& T& /em& & /strong& ) and subsurface heat content (thermocline depth & strong& & em& h& /em& & /strong& ) have an out-of-phase relationship. This defines a 2-dimensional phase space diagram between & strong& & em& T& /em& & /strong& and & strong& & em& h& /em& & /strong& . In an idealized d ed oscillator, the phase space diagram should be a perfectly symmetrical circle with a clockwise propagation over time. However, the observed phase space shows strong asymmetries in this diagram. In this study we will illustrate how the ENSO phase space can be used to discuss the phase-dependency of ENSO dynamics. The normalized spherical coordinate system allows to define a phase-depending ENSO growth rates and phase transition speeds. Based on these we discuss the implications of the observed asymmetries are for the dynamics and predictability of ENSO, with a particular focus on the variations in the growth rate and coupling of ENSO along the oscillation cycle.& Using linear and non-linear recharge oscillator models we will show how noise and internal dynamics are driving ENSO at different phases of the ENSO cycles. We will illustrate that a non-linear growth rate of & strong& & em& T& /em& & /strong& can explain most of the observed non-linear phase space characteristics.& &
Atmospheric response to sea surface temperature anomalies during El Nino 1997/98 as simulated by ECHAM4
Publisher: Wiley
Date: 15-07-2000
DOI: 10.1256/SMSQJ.56709
The Impact of North Atlantic–Arctic Multidecadal Variability on Northern Hemisphere Surface Air Temperature
Publisher: American Meteorological Society
Date: 11-2010
Abstract: The twentieth-century Northern Hemisphere surface climate exhibits a long-term warming trend largely caused by anthropogenic forcing, with natural decadal climate variability superimposed on it. This study addresses the possible origin and strength of internal decadal climate variability in the Northern Hemisphere during the recent decades. The authors present results from a set of climate model simulations that suggest natural internal multidecadal climate variability in the North Atlantic–Arctic sector could have considerably contributed to the Northern Hemisphere surface warming since 1980. Although covering only a few percent of the earth’s surface, the Arctic may have provided the largest share in this. It is hypothesized that a stronger meridional overturning circulation in the Atlantic and the associated increase in northward heat transport enhanced the heat loss from the ocean to the atmosphere in the North Atlantic region and especially in the North Atlantic portion of the Arctic because of anomalously strong sea ice melt. The model results stress the potential importance of natural internal multidecadal variability originating in the North Atlantic–Arctic sector in generating interdecadal climate changes, not only on a regional scale, but also possibly on a hemispheric and even a global scale.
authors respond to all referee comments (RCs)
Publisher: Copernicus GmbH
Date: 15-11-2018
A hydrological cycle model for the Globally Resolved Energy Balance (GREB) model v1.0
Publisher: Copernicus GmbH
Date: 24-01-2019
Abstract: Abstract. This study describes the development of the hydrological cycle model for the Globally Resolved Energy Balance (GREB) model. Starting from a rudimentary hydrological cycle model included in the GREB model, we develop three new models: precipitation, evaporation and horizontal transport of water vapour. Precipitation is modelled based on the actual simulated specific and relative humidity in GREB and the prescribed boundary condition of vertical velocity. The evaporation bulk formula is slightly refined by considering differences in the sensitivity to winds between land and oceans, and by improving the estimates of the wind magnitudes. Horizontal transport of water vapour is improved by approximating moisture convergence by vertical velocity. The new parameterisations are fitted against the Global Precipitation Climatology Project (GPCP) data set and reanalysis data sets (ERA-Interim). The new hydrological cycle model is evaluated against the Coupled Model Intercomparison Project phase 5 (CMIP5) model simulations, reduction in correction terms and by three different sensitivity experiments (annual cycle, El Niño–Southern Oscillation and climate change). The skill of the hydrological cycle model in the GREB model is now within the range of more complex CMIP5 coupled general circulation models and capable of simulating key features of the climate system within the range of uncertainty of CMIP5 model simulations. The results illustrate that the new GREB model's hydrological cycle is a useful model to study the climate's hydrological response to external forcings and also to study inter-model differences or biases.
Predictions of Indian Ocean SST Indices with a Simple Statistical Model: A Null Hypothesis
Publisher: American Meteorological Society
Date: 15-09-2009
Abstract: Several recent general circulation model studies discuss the predictability of the Indian Ocean dipole (IOD) mode, suggesting that it is predictable because of coupled ocean–atmosphere interactions in the Indian Ocean. However, it is not clear from these studies how much of the predictability is due to the response to El Niño. It is shown in this note that a simple statistical model that treats the Indian Ocean as a red noise process forced by tropical Pacific SST shows forecast skills comparable to those of recent general circulation model studies. The results also indicate that some of the eastern tropical Indian Ocean SST predictability in recent studies may indeed be beyond the skill of the simple model proposed in this note, indicating that dynamics in the Indian Ocean may have caused this improved predictability in this region. The model further indicates that the IOD index may be the least predictable index of Indian Ocean SST variability. The model is proposed as a null hypothesis for Indian Ocean SST predictions.
Generation of hyper climate modes
Publisher: American Geophysical Union (AGU)
Date: 2008
DOI: 10.1029/2007GL031087
Exploration of Atmosphere‐Only Model Deficiencies in Reproducing the 1992–2011 Pacific Trade Wind Acceleration
Publisher: American Geophysical Union (AGU)
Date: 09-09-2022
DOI: 10.1029/2022GL099981
Abstract: A robust simulation of tropical Pacific Ocean decadal‐scale zonal wind stress trends can increase the confidence in projections of global surface temperature and regional sea level rise, yet coupled general circulation models simulate weaker trends than observed. When forced with observed sea surface temperatures, the atmospheric component of these models still simulates a weaker zonal wind stress trend during 1992–2008 (and 1992–2011) than observed. Yet, this decadal wind trend bias is not evident at the 850 hPa level. We show that the modelled wind trend bias is related to deficiencies in monthly wind stress variability. Furthermore, the strength of the connectivity between the surface and 850 hPa was also an indicator of the wind stress trend. Models that simulated a more realistic wind stress trend tend to simulate a stronger Pacific zonal sea level pressure gradient intensification than observed and a South Pacific Convergence Zone shift like that observed.
Influences of the tropical Indian and Atlantic Oceans on the predictability of ENSO
Publisher: American Geophysical Union (AGU)
Date: 2012
DOI: 10.1029/2011GL050520
Counteracting global warming by using a locally optimized solar radiation management
Publisher: Wiley
Date: 16-08-2021
Supplementary material to "GREB-ISM v0.3: A coupled ice sheet model for the Global Resolved Energy Balance model for global simulations on time-scales of 100 kyr"
Publisher: Copernicus GmbH
Date: 26-07-2021
GREB-ISM v0.3: A coupled ice sheet model for the Global Resolved Energy Balance model for global simulations on time-scales of 100 kyr
Publisher: Copernicus GmbH
Date: 26-07-2021
DOI: 10.5194/GMD-2021-204
Abstract: Abstract. We introduce a newly developed global ice sheet model coupled to the Globally Resolved Energy Balance (GREB) climate model for the simulation of global ice sheet evolution on time scales of 100 kyr or longer (GREB-ISM v0.3). Ice sheets and ice shelves are simulated on a global grid, fully interacting with the climate simulation of surface temperature, precipitation, albedo, land-sea mask, topography and sea level. Thus, it is a fully coupled atmosphere, ocean, land and ice sheet model. We test the model in ice sheet stand-alone and fully coupled simulations. The ice sheet model dynamics behave similarly to other hybrid SIA (Shallow Ice Approximation) and SSA (Shallow Shelf Approximation) models, but the West Antarctic Ice Sheet accumulates too much ice using present-day boundary conditions. The coupled model simulations produce global equilibrium ice sheet volumes and calving rates similar to observed for present day boundary conditions. We designed a series of idealised experiments driven by oscillating solar radiation forcing on periods of 20 kyr, 50 kyr and 100 kyr in the Northern Hemisphere. These simulations show clear interactions between the climate system and ice sheets, resulting in slow build-up and fast decay of ice-covered areas and global ice volume. The results also show that Northern Hemisphere ice sheets respond more strongly to time scales longer than 100 kyr. The coupling to the atmosphere and sea level leads to climate interactions between the Northern and Southern Hemispheres. The model can run global simulations of 100 kyr per day on a desktop computer, allowing the simulation of the whole Quaternary period (2.6 Myrs) within one month.
Widespread Reemergence of Sea Surface Temperature Anomalies in the Global Oceans, Including Tropical Regions Forced by Reemerging Winds
Publisher: American Geophysical Union (AGU)
Date: 11-08-2018
DOI: 10.1029/2018GL079137
An objective analysis of the observed spatial structure of the tropical Indian Ocean SST variability
Publisher: Springer Science and Business Media LLC
Date: 23-03-2010
The Dynamics of the El-Niño Southern Oscillation (ENSO) Diversity
Publisher: Copernicus GmbH
Date: 15-05-2023
DOI: 10.5194/EGUSPHERE-EGU23-2470
Abstract: This study investigates the observed El-Ni& #241 o Southern Oscillation (ENSO) dynamics for the eastern Pacific (EP) and central Pacific (CP) events. Here we use the recharge oscillator (ReOsc) model concept to describe the ENSO phase space, based on the interaction of sea surface temperatures in the eastern equatorial Pacific (T) and thermocline depth (h), for the different types of ENSO events. We further look at some important statistical characteristics, such as power spectrum and cross-correlation, as essential parameters for understanding the dynamics of ENSO. The results show that the CP and EP events are very different in the ENSO phase space and less well described by the ReOsc model than a T index-based model. The EP events are closer to the idealised ReOsc model, with clear propagation through all phases of the ENSO cycle and strongly skewed towards the El-Ni& #241 o and subsurface ocean heat discharge states. The CP events, in turn, do not have a clear propagation through all phases and are strongly skewed towards the La-Nina state. Also, the CP events have a slower cycle (67 months) than the EP events (50 months). Further, the CP events collapse after the La-Nina phase, whereas the EP events appear to collapse after the discharging phase. The characteristics out-of-phase cross-correlation between T and h is nearly absent for the CP events, suggesting that the interaction between T and h is not as important as for the EP or the canonical ENSO events. Furthermore, the coupling factor of T and h is smaller for the CP events than the EP events, implying that the CP events are not influenced much by T and h interactions. This study will provide new insight to understand these events by developing a dynamical approach to explain the observed ENSO dynamics for the EP and CP events in the ReOsc model framework.
Counteracting global warming by using a locally variable Solar Radiation Management
Publisher: Copernicus GmbH
Date: 23-03-2020
DOI: 10.5194/EGUSPHERE-EGU2020-12307
Abstract: & & Solar Radiation Management (SRM) is regarded as a tool which could potentially mitigate or completely offset global warming by increasing planetary albedo. However, this approach could potentially reduce precipitation as well, as shown in the latest Intergovernmental Panel on Climate Change (ICPP) 5& sup& th& /sup& report. Thus, although SRM might weaken global climate risks, it may enhance those in some regions. Here, using the Globally Resolved Energy Balance (GREB) model, we present experiments designed to completely offset the temperature and precipitation response due to a& CO& sub& & /sub& -doubling experiment (abrupt2& #215 CO2). The main idea around which our study is built upon is to employ a localized and seasonally varying SRM, as opposed to the most recent Geo-Engineering experiments which just apply a global and homogeneous one. In order to achieve such condition, we carry out the computation by using an & #8220 artificial cloud cover& #8221 . The usage of this localized approach allows us to globally cut down temperature warming in the abrupt2& #215 CO2 scenario by 99.8% (which corresponds to an increase of 0.07 & #176 C on a global average basis), while at the same time only having minor changes in precipitation (0.003 mm/day on a global average basis). To achieve this the cloud cover is increased by about 8% on a global average. Moreover, neither temperature nor precipitation response are exacerbated when averaged over any IPCC Special Report on Extremes (SREX) region. Indeed, for temperatures, 90% of SREX regions averages fall within 0.3 & #176 C change, with all regional mean anomalies being under 0.38 & #176 C. Whereas, as far as precipitation is concerned, changes go up to 0.01 mm/day for 90% of SREX regions, with all of them changing by less than 0.02 mm/day. Similar results are achieved for seasonal variations, with Seasonal Cycle (DJF-JJA) having no major changes in both surface temperature and precipitation.& &
Supplementary material to "Reduced complexity model intercomparison project phase 1: Protocol, results and initial observations"
Publisher: Copernicus GmbH
Date: 21-01-2020
Comparing the spatial structure of variability in two datasets against each other on the basis of EOF-modes
Publisher: Springer Science and Business Media LLC
Date: 12-03-2013
Related Organisations
Related Funding Activities
Discovery Projects - Grant ID: DP120101442
Start Date: 07-2012
End Date: 12-2017
Amount: $325,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP200102329
Start Date: 06-2020
End Date: 06-2024
Amount: $410,000.00
Funder: Australian Research Council
View Funded ActivityDiscovery Projects - Grant ID: DP220101468
Start Date: 06-2022
End Date: 06-2025
Amount: $423,961.00
Funder: Australian Research Council
View Funded ActivityLinkage Projects - Grant ID: LP120200217
Start Date: 05-2013
End Date: 12-2017
Amount: $396,203.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE170100023
Start Date: 08-2017
End Date: 12-2024
Amount: $30,050,000.00
Funder: Australian Research Council
View Funded ActivityARC Centres Of Excellence - Grant ID: CE1101028
Start Date: 07-2011
End Date: 06-2018
Amount: $21,400,000.00
Funder: Australian Research Council
View Funded ActivityLinkage Infrastructure, Equipment And Facilities - Grant ID: LE150100089
Start Date: 2015
End Date: 12-2015
Amount: $490,000.00
Funder: Australian Research Council
View Funded Activity