Regional Climate Modeler using the stretched grid CCAM.I have expertise in the analysis and communication of climate projections.I also have extensive experience in very high-resolution weather forecasting.
Asia-Pacific Journal of Atmospheric Sciences, 2016
To assist the government of Vietnam in its efforts to better understand the impacts of climate ch... more To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (-60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.
This report describes simulations of climate change and variability under enhanced greenhouse con... more This report describes simulations of climate change and variability under enhanced greenhouse conditions in northern Australia. This The work of the authors draws upon research findings of many colleagues within the Division of Atmospheric Research. CSIRO global climate models (GCMs) were developed largely by the members of the Climate Modelling Group of this Division. John McGregor, Jack Katzfey and Kim Nguyen carried out the limited-area modelling experiments. Barrie Hunt and Ian Smith have done the GCM experiment with observed SST. Their continued cooperation and support is greatly appreciated. is the final report of a three year consultancy (1994-97) with the Governments of the Northern Territory, Western Australia and Queensland. Five climatic aspects are assessed: (1) the interaction between the monsoon, tropical cyclones, the El Nino - Southern Oscillation (ENSO) phenomenon and variations within the monsoon season, (2) the ability of regional and global climate models to simu...
This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the ... more This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the 9th Asia-Pacific Conference on Wind Engineering, University of Auckland, Auckland, New Zealand, held from 3-7 December 2017.
Global warming is likely to cause a progressive drought increase in some regions, but how populat... more Global warming is likely to cause a progressive drought increase in some regions, but how population and natural resources will be affected is still underexplored. This study focuses on global population and land-use (forests, croplands, pastures) exposure to meteorological drought hazard in the 21st century, expressed as frequency and severity of drought events. As input, we use a large ensemble of climate simulations from the Coordinated Regional Climate Downscaling Experiment, population projections from the NASA-SEDAC dataset, and land-use projections from the Land-Use Harmonization 2 project for 1981–2100. The exposure to drought hazard is presented for five SSPs (SSP1-SSP5) at four Global Warming Levels (GWLs, from 1.5 to 4°C). Results show that considering only Standardized Precipitation Index (SPI; based on precipitation), the combination SSP3-GWL4 projects the largest fraction of the global population (14%) to experience an increase in drought frequency and severity (vs. 1981–2010), with this value increasing to 60% if temperature is considered (indirectly included in the Standardized Precipitation-Evapotranspiration Index, SPEI). With SPEI, considering the highest GWL for each SSP, 8 (for SSP2, SSP4, and SSP5) and 11 (SSP3) billion people, that is, more than 90%, will be affected by at least one unprecedented drought. For SSP5 (fossil-fuelled development) at GWL 4°C, approximately 2·106 km2 of forests and croplands (respectively, 6 and 11%) and 1.5·106 km2 of pastures (19%) will be exposed to increased drought frequency and severity according to SPI, but for SPEI, this extent will rise to 17·106 km2 of forests (49%), 6·106 km2 of pastures (78%), and 12·106 km2 of croplands (67%), with mid-latitudes being the most affected areas. The projected likely increase of drought frequency and severity significantly increases population and land-use exposure to drought, even at low GWLs, thus extensive mitigation and adaptation efforts are needed to avoid the most severe impacts of climate change.we
Two questions motivated this study: 1) Will meteorological droughts become more frequent and seve... more Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the 21st century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators, play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981-2100, using Standardized Precipitation Index (SPI, including precipitation only) and Standardized Precipitation-Evapotranspiration Index (SPEI, indirectly including temperature), and under two Representative Concentration Pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.44°) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of sixteen Global Circulation Models (GCMs) and twenty Regional Circulation Models (RCMs). This is the first study on global drought proj...
Under the framework of the Regional Climate Model Intercomparison Project (RMIP III), simulation ... more Under the framework of the Regional Climate Model Intercomparison Project (RMIP III), simulation results from six regional climate models (RCMs) and two global climate models (GCMs) were used to generate climate extreme indices for the present and future over China using two ensemble methods. All the models reasonably captured the observed climate extremes, and performance-based ensemble averaging (PEA) outperformed the individual model and equal-weighted averaging (MME) for the control climate. However, noticeable cold deficiencies in temperature extremes were found over areas with complex topography, and too frequent heavy precipitation at smaller intensities was simulated using the multiple model ensembles. Under the A1B scenario for 2041–2060, widespread increases in the 90th percentiles of the maximum temperatures (Tmax90p) and the 10th percentile of the minimum temperatures (Tmin10p) were projected, with larger increases in winter than in summer. Greater intensities in precipitation extremes were projected over China, with the exception of Inner Mongolia. Large uncertainties exist in the projected mean diurnal temperature range (Trange), number of days with precipitation exceeding 10 mm (R10) and the maximum number of consecutive dry days (CDD) because of disagreements in both the magnitudes and signs of the climate model projections, and even the two ensemble methods presented opposite signs over some regions.
World population and industrialization have increased significantly, leading to an increase in gl... more World population and industrialization have increased significantly, leading to an increase in global energy demand, mainly relying on fossil fuels. Use of alternative energy sources such as wind, hydro and solar has been steadily increasing. Australia is a vast continent which receives an average 58 million PJ of energy from the sun annually. Given this resource potential, one could envisage construction of massive solar farms to help meet energy demands. If such constructions went ahead, their potential benefits/impacts on the climate over and surrounding the solar arrays would need to be investigated. Here, we study the potential climatic impacts over and in the environment surrounding massive hypothetical solar sites across Australia using a global stretched grid atmospheric model. The solar farms are represented by modelling the effects of perturbing surface albedo and surface roughness. The sensitivity experiments incorporate different combinations of surface albedos, shapes and locations of the solar farms, with a focus on the summer season. Our study suggests that depending on array sizes, locations, orientations and surface albedo (potentially increased by means of highly reflective in-fill material), the climate over solar arrays could be modified significantly. Over the arrays with positive albedo perturbation, rainfall would decrease by around 30–70%, and daytime maximum air temperatures would decrease up to 10 °C. In addition, solar irradiance would increase by around 5–20%, which combined with the air temperature cooling, would lead to an enhanced solar power yield up to 25%.
Journal of Geophysical Research: Atmospheres, 2016
Bias correction is a widely used method to deal with the deficiencies of climate models in repres... more Bias correction is a widely used method to deal with the deficiencies of climate models in representing the current climate. While it is mainly applied to prepare the output of global or regional climate models (GCMs/RCMs) for climate impact assessment, it has also been used recently to correct GCM output before it is downscaled by RCMs. For most RCMs, 3-D atmospheric fields as well as sea surface temperatures (SSTs) should be corrected in order to create forcing fields. The global stretched grid, conformal-cubic atmospheric model (CCAM), is able to run regional simulations with SST-only forcing. Therefore, only the monthly SSTs obtained from the GCM need to be corrected. In previous studies, the climatological bias was removed, while the bias in the temporal variability was still present. In this study, a simple method for correction of the mean and variance is proposed. The impact of the bias correction is tested using global even-grid CCAM simulations forced with raw and corrected SSTs from ACCESS1.0. Results indicate an improved precipitation pattern in the tropics for all seasons using corrected SSTs. There is also a slight improvement in the precipitation pattern in December–February and March–May and in the response to the El Nino–Southern Oscillation due to the additional variance correction.
Under the Asia-Pacific Network for Global Change (APN) project ‘Building Asian Climate Change Sce... more Under the Asia-Pacific Network for Global Change (APN) project ‘Building Asian Climate Change Scenarios by Multi-Regional Climate Models Ensemble’ (RMIP III, Regional Model Intercomparision Project), the simulation results of eight regional climate models (RCMs) and two fine-resolution global climate models are validated for reproducibility of the current surface air temperature climatology (1981–2000), and are used to generate surface air future temperature projections (2041–2060) over the CORDEX-EA (A Coordinated Regional climate Downscaling Experiment-East Asia) domain. Four ensemble methods, namely, the equal weighting, the weighted mean, the reliability ensemble averaging, and the performance-based ensemble averaging, are employed to generate the multi-model projection of regional climate change over the region. The results show that the regional temperature ensembles of the present climate obtained from all four methods can outperform a single RCM result in aspects of the spatial distribution as well as the seasonal variation over East Asia. The four ensemble methods are then used to project the regional temperature climatology under the IPCC emission scenario of A1B for 2041–2060. Compared with the control climate of 1981–2000, the annual mean temperature of the future climate (2041–2060) increases 1–2 °C in low latitude areas and 2–3 °C in middle–high latitude areas over Asia.
NEMSIM is an agent-based simulation model under development that represents Australia's Natio... more NEMSIM is an agent-based simulation model under development that represents Australia's National Electricity Market (NEM) as an evolving system of complex interactions between human behaviour in markets, technical infrastructures and the natural environment. Users of NEMSIM will be able to explore various evolutionary pathways of the NEM under different assumptions about trading and investment opportunities, institutional changes and technological futures – including alternative learning patterns as participants grow and change. The simulated outcomes will help the user to identify futures that are eco-efficient – e.g. maximising profits in a potentially carbonconstrained or environmentally regulated future. The NEMSIM project is part of CSIRO's Energy Transformed Flagship research program, which aims to provide innovative solutions for Australia's pressing energy needs. Motivation for the project is the Flagship's mission to develop low emission energy systems and t...
Asia-Pacific Journal of Atmospheric Sciences, 2016
To assist the government of Vietnam in its efforts to better understand the impacts of climate ch... more To assist the government of Vietnam in its efforts to better understand the impacts of climate change and prioritise its adaptation measures, dynamically downscaled climate change projections were produced across Vietnam. Two Regional Climate Models (RCMs) were used: CSIRO’s variable-resolution Conformal-Cubic Atmospheric Model (CCAM) and the limited-area model Regional Climate Model system version 4.2 (RegCM4.2). First, global CCAM simulations were completed using bias- and variance-corrected sea surface temperatures as well as sea ice concentrations from six Coupled Model Intercomparison Project Phase 5 (CMIP5) global climate models. This approach is different from other downscaling approaches as it does not use any atmospheric fields from the GCMs. The global CCAM simulations were then further downscaled to 10 km using CCAM and to 20 km using RegCM4.2. Evaluations of temperature and precipitation for the current climate (1980-2000) were completed using station data as well as various gridded observational datasets. The RCMs were able to reproduce reasonably well most of the important characteristics of observed spatial patterns and annual cycles of temperature. Average and minimum temperatures were well simulated (biases generally less than 1oC), while maximum temperatures had biases of around 1oC. For precipitation, although the RCMs captured the annual cycle, RegCM4.2 was too dry in Oct.-Nov. (-60% bias), while CCAM was too wet in Dec.- Mar. (130% bias). Both models were too dry in summer and too wet in winter (especially in northern Vietnam). The ability of the ensemble simulations to capture current climate increases confidence in the simulations of future climate.
This report describes simulations of climate change and variability under enhanced greenhouse con... more This report describes simulations of climate change and variability under enhanced greenhouse conditions in northern Australia. This The work of the authors draws upon research findings of many colleagues within the Division of Atmospheric Research. CSIRO global climate models (GCMs) were developed largely by the members of the Climate Modelling Group of this Division. John McGregor, Jack Katzfey and Kim Nguyen carried out the limited-area modelling experiments. Barrie Hunt and Ian Smith have done the GCM experiment with observed SST. Their continued cooperation and support is greatly appreciated. is the final report of a three year consultancy (1994-97) with the Governments of the Northern Territory, Western Australia and Queensland. Five climatic aspects are assessed: (1) the interaction between the monsoon, tropical cyclones, the El Nino - Southern Oscillation (ENSO) phenomenon and variations within the monsoon season, (2) the ability of regional and global climate models to simu...
This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the ... more This paper was reviewed and accepted by the APCWE-IX Programme Committee for Presentation at the 9th Asia-Pacific Conference on Wind Engineering, University of Auckland, Auckland, New Zealand, held from 3-7 December 2017.
Global warming is likely to cause a progressive drought increase in some regions, but how populat... more Global warming is likely to cause a progressive drought increase in some regions, but how population and natural resources will be affected is still underexplored. This study focuses on global population and land-use (forests, croplands, pastures) exposure to meteorological drought hazard in the 21st century, expressed as frequency and severity of drought events. As input, we use a large ensemble of climate simulations from the Coordinated Regional Climate Downscaling Experiment, population projections from the NASA-SEDAC dataset, and land-use projections from the Land-Use Harmonization 2 project for 1981–2100. The exposure to drought hazard is presented for five SSPs (SSP1-SSP5) at four Global Warming Levels (GWLs, from 1.5 to 4°C). Results show that considering only Standardized Precipitation Index (SPI; based on precipitation), the combination SSP3-GWL4 projects the largest fraction of the global population (14%) to experience an increase in drought frequency and severity (vs. 1981–2010), with this value increasing to 60% if temperature is considered (indirectly included in the Standardized Precipitation-Evapotranspiration Index, SPEI). With SPEI, considering the highest GWL for each SSP, 8 (for SSP2, SSP4, and SSP5) and 11 (SSP3) billion people, that is, more than 90%, will be affected by at least one unprecedented drought. For SSP5 (fossil-fuelled development) at GWL 4°C, approximately 2·106 km2 of forests and croplands (respectively, 6 and 11%) and 1.5·106 km2 of pastures (19%) will be exposed to increased drought frequency and severity according to SPI, but for SPEI, this extent will rise to 17·106 km2 of forests (49%), 6·106 km2 of pastures (78%), and 12·106 km2 of croplands (67%), with mid-latitudes being the most affected areas. The projected likely increase of drought frequency and severity significantly increases population and land-use exposure to drought, even at low GWLs, thus extensive mitigation and adaptation efforts are needed to avoid the most severe impacts of climate change.we
Two questions motivated this study: 1) Will meteorological droughts become more frequent and seve... more Two questions motivated this study: 1) Will meteorological droughts become more frequent and severe during the 21st century? 2) Given the projected global temperature rise, to what extent does the inclusion of temperature (in addition to precipitation) in drought indicators, play a role in future meteorological droughts? To answer, we analyzed the changes in drought frequency, severity, and historically undocumented extreme droughts over 1981-2100, using Standardized Precipitation Index (SPI, including precipitation only) and Standardized Precipitation-Evapotranspiration Index (SPEI, indirectly including temperature), and under two Representative Concentration Pathways (RCP4.5 and RCP8.5). As input data, we employed 103 high-resolution (0.44°) simulations from the Coordinated Regional Climate Downscaling Experiment (CORDEX), based on a combination of sixteen Global Circulation Models (GCMs) and twenty Regional Circulation Models (RCMs). This is the first study on global drought proj...
Under the framework of the Regional Climate Model Intercomparison Project (RMIP III), simulation ... more Under the framework of the Regional Climate Model Intercomparison Project (RMIP III), simulation results from six regional climate models (RCMs) and two global climate models (GCMs) were used to generate climate extreme indices for the present and future over China using two ensemble methods. All the models reasonably captured the observed climate extremes, and performance-based ensemble averaging (PEA) outperformed the individual model and equal-weighted averaging (MME) for the control climate. However, noticeable cold deficiencies in temperature extremes were found over areas with complex topography, and too frequent heavy precipitation at smaller intensities was simulated using the multiple model ensembles. Under the A1B scenario for 2041–2060, widespread increases in the 90th percentiles of the maximum temperatures (Tmax90p) and the 10th percentile of the minimum temperatures (Tmin10p) were projected, with larger increases in winter than in summer. Greater intensities in precipitation extremes were projected over China, with the exception of Inner Mongolia. Large uncertainties exist in the projected mean diurnal temperature range (Trange), number of days with precipitation exceeding 10 mm (R10) and the maximum number of consecutive dry days (CDD) because of disagreements in both the magnitudes and signs of the climate model projections, and even the two ensemble methods presented opposite signs over some regions.
World population and industrialization have increased significantly, leading to an increase in gl... more World population and industrialization have increased significantly, leading to an increase in global energy demand, mainly relying on fossil fuels. Use of alternative energy sources such as wind, hydro and solar has been steadily increasing. Australia is a vast continent which receives an average 58 million PJ of energy from the sun annually. Given this resource potential, one could envisage construction of massive solar farms to help meet energy demands. If such constructions went ahead, their potential benefits/impacts on the climate over and surrounding the solar arrays would need to be investigated. Here, we study the potential climatic impacts over and in the environment surrounding massive hypothetical solar sites across Australia using a global stretched grid atmospheric model. The solar farms are represented by modelling the effects of perturbing surface albedo and surface roughness. The sensitivity experiments incorporate different combinations of surface albedos, shapes and locations of the solar farms, with a focus on the summer season. Our study suggests that depending on array sizes, locations, orientations and surface albedo (potentially increased by means of highly reflective in-fill material), the climate over solar arrays could be modified significantly. Over the arrays with positive albedo perturbation, rainfall would decrease by around 30–70%, and daytime maximum air temperatures would decrease up to 10 °C. In addition, solar irradiance would increase by around 5–20%, which combined with the air temperature cooling, would lead to an enhanced solar power yield up to 25%.
Journal of Geophysical Research: Atmospheres, 2016
Bias correction is a widely used method to deal with the deficiencies of climate models in repres... more Bias correction is a widely used method to deal with the deficiencies of climate models in representing the current climate. While it is mainly applied to prepare the output of global or regional climate models (GCMs/RCMs) for climate impact assessment, it has also been used recently to correct GCM output before it is downscaled by RCMs. For most RCMs, 3-D atmospheric fields as well as sea surface temperatures (SSTs) should be corrected in order to create forcing fields. The global stretched grid, conformal-cubic atmospheric model (CCAM), is able to run regional simulations with SST-only forcing. Therefore, only the monthly SSTs obtained from the GCM need to be corrected. In previous studies, the climatological bias was removed, while the bias in the temporal variability was still present. In this study, a simple method for correction of the mean and variance is proposed. The impact of the bias correction is tested using global even-grid CCAM simulations forced with raw and corrected SSTs from ACCESS1.0. Results indicate an improved precipitation pattern in the tropics for all seasons using corrected SSTs. There is also a slight improvement in the precipitation pattern in December–February and March–May and in the response to the El Nino–Southern Oscillation due to the additional variance correction.
Under the Asia-Pacific Network for Global Change (APN) project ‘Building Asian Climate Change Sce... more Under the Asia-Pacific Network for Global Change (APN) project ‘Building Asian Climate Change Scenarios by Multi-Regional Climate Models Ensemble’ (RMIP III, Regional Model Intercomparision Project), the simulation results of eight regional climate models (RCMs) and two fine-resolution global climate models are validated for reproducibility of the current surface air temperature climatology (1981–2000), and are used to generate surface air future temperature projections (2041–2060) over the CORDEX-EA (A Coordinated Regional climate Downscaling Experiment-East Asia) domain. Four ensemble methods, namely, the equal weighting, the weighted mean, the reliability ensemble averaging, and the performance-based ensemble averaging, are employed to generate the multi-model projection of regional climate change over the region. The results show that the regional temperature ensembles of the present climate obtained from all four methods can outperform a single RCM result in aspects of the spatial distribution as well as the seasonal variation over East Asia. The four ensemble methods are then used to project the regional temperature climatology under the IPCC emission scenario of A1B for 2041–2060. Compared with the control climate of 1981–2000, the annual mean temperature of the future climate (2041–2060) increases 1–2 °C in low latitude areas and 2–3 °C in middle–high latitude areas over Asia.
NEMSIM is an agent-based simulation model under development that represents Australia's Natio... more NEMSIM is an agent-based simulation model under development that represents Australia's National Electricity Market (NEM) as an evolving system of complex interactions between human behaviour in markets, technical infrastructures and the natural environment. Users of NEMSIM will be able to explore various evolutionary pathways of the NEM under different assumptions about trading and investment opportunities, institutional changes and technological futures – including alternative learning patterns as participants grow and change. The simulated outcomes will help the user to identify futures that are eco-efficient – e.g. maximising profits in a potentially carbonconstrained or environmentally regulated future. The NEMSIM project is part of CSIRO's Energy Transformed Flagship research program, which aims to provide innovative solutions for Australia's pressing energy needs. Motivation for the project is the Flagship's mission to develop low emission energy systems and t...
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Papers by Jack Katzfey