Danielle C Verdon-Kidd, Anthony S Kiem, Garry R Willgoose
East Coast Lows (ECLs) are intense low pressure systems that form several times a year off the east coast of Australia. When these systems occur close to land they can cause major damage to infrastructure and communities due to gale force winds, intense rainfall, storm surge and coastal erosion. In June 2007, Newcastle and Central Coast regions of New South Wales (NSW) experienced severe weather and subsequent flash flooding. The ‘Pasha Bulker’ storm, as it has become known, was one of the most significant meteorological events in Australia’s history, with large economic losses and social disruption due to the loss of critical infrastructure. This paper provides background information on the meteorology of the event, the impact of the Pasha Bulker storm and a discussion of the lessons learned from the event and subsequent adaptation strategies employed. The paper also provides important reflections, at both regional and national level, on the Pasha Bulker storm and other similar storm events. Lessons for all levels of government and community groups are discussed, including preparedness before the event, actions during the event, and recovery processes post-event. From this, recommendations and conclusions are made on actions and strategies to increase adaptive capacity and resilience to extreme weather events like ECLs.
{"title":"East Coast Lows and the Pasha Bulker storm - lessons learned nine years on","authors":"Danielle C Verdon-Kidd, Anthony S Kiem, Garry R Willgoose","doi":"10.1071/es16013","DOIUrl":"https://doi.org/10.1071/es16013","url":null,"abstract":"East Coast Lows (ECLs) are intense low pressure systems that form several times a year off the east coast of Australia. When these systems occur close to land they can cause major damage to infrastructure and communities due to gale force winds, intense rainfall, storm surge and coastal erosion. In June 2007, Newcastle and Central Coast regions of New South Wales (NSW) experienced severe weather and subsequent flash flooding. The ‘Pasha Bulker’ storm, as it has become known, was one of the most significant meteorological events in Australia’s history, with large economic losses and social disruption due to the loss of critical infrastructure. This paper provides background information on the meteorology of the event, the impact of the Pasha Bulker storm and a discussion of the lessons learned from the event and subsequent adaptation strategies employed. The paper also provides important reflections, at both regional and national level, on the Pasha Bulker storm and other similar storm events. Lessons for all levels of government and community groups are discussed, including preparedness before the event, actions during the event, and recovery processes post-event. From this, recommendations and conclusions are made on actions and strategies to increase adaptive capacity and resilience to extreme weather events like ECLs.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"48 12","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138509311","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A seasonal climatology of the 1965-1975 Melbourne ozonesonde ozone profile record is presented, spanning a period when minimal stratospheric ozone chemical depletion existed and prior to adequate satellite ozone profiling. Results are presented as monthly isentropic weighted means of ozone mixing ratio and partial pressure, with associated uncertainties, plotted against potential temperature and altitude. Corrections for pump inefficiency and referencing to the current ozonesonde type are included. The general seasonal and altitudinal features of the results are consistent with our current understanding of ozone variations in the southern mid-latitudes. These results are of value to atmospheric chemical and climate change models.
{"title":"A seasonal climatology of the Melbourne 1965-1975 ozonesonde record","authors":"Paul Lehmann","doi":"10.1071/es16018","DOIUrl":"https://doi.org/10.1071/es16018","url":null,"abstract":"A seasonal climatology of the 1965-1975 Melbourne ozonesonde ozone profile record is presented, spanning a period when minimal stratospheric ozone chemical depletion existed and prior to adequate satellite ozone profiling. Results are presented as monthly isentropic weighted means of ozone mixing ratio and partial pressure, with associated uncertainties, plotted against potential temperature and altitude. Corrections for pump inefficiency and referencing to the current ozonesonde type are included. The general seasonal and altitudinal features of the results are consistent with our current understanding of ozone variations in the southern mid-latitudes. These results are of value to atmospheric chemical and climate change models.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"47 10","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138509314","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Natalie Lockart, Garry Willgoose, George Kuczera, Anthony S. Kiem, AFM Kamal Chowdhury, Nadeeka Parana Manage, Lanying Zhang, Callum Twomey
A key aim of the Eastern Seaboard Climate Change Initiative (ESCCI) is under-standing the effect of climate change on the eastern seaboard of Australia, and the implications for climate change adaptation in this area. The New South Wales (NSW) / Australian Capital Territory (ACT) Regional Climate Modelling project (NARCliM) has produced three dynamically downscaled reanalysis climate datasets along with 12 downscaled general circulation model (GCM) projections of current (1990–2009) and future climate. It is expected that the NARCliM dataset will be used for many climate change impact studies including water security assessment. Therefore, in this study we perform a case study investigation into the usefulness and limitations of using NARCliM data for water security assessment, using the Lower Hunter urban water supply system managed by Hunter Water Corporation. We compare streamflow and reservoir levels simulated using NARCliM rainfall and a gridded historical rainfall dataset (AWAP) and focus our analysis on the differences in the simulated streamflow and reservoir levels. We show that when raw (i.e. not bias-corrected) NARCliM rainfall and potential evapotranspiration (PET) data is used to simulate streamflow and reservoir storage levels, some of the NARCliM datasets produce unrealistic results when compared with the simulations using AWAP; for example, some NARCliM datasets simulate reservoirs at or near empty while the AWAP reservoir simulations rarely drop below 60%. The bias-corrected NARCliM rainfall (corrected to AWAP) produces estimates of streamflow and reservoir levels that have a closer, but still inconsistent, match with the streamflow and reservoir levels simulated using AWAP directly. The inconsistency between the simulations using bias-corrected rainfall and historical AWAP rainfall is potentially because while bias-correction reduces systematic deviations it does not fix temporal rainfall sequencing issues. Additionally, the NARCliM PET is not bias-corrected and using bias-corrected rainfall with uncorrected PET in hydrological models results in physical inconsistencies in the rainfall-PET relationship and simulated streamflow. We demonstrate that rainfall plays a large role in the streamflow simulations, while PET seems to play a large role in the reasonableness of the simulated reservoir dynamics by determining the evaporation losses from the reservoirs. The downscaled GCM datasets that simulate the greatest average PET for 1990–2009 show reservoirs often (unrealistically) near empty. This study highlights the need to assess the validity of all climate data for the applications required, with a focus on long-term statistics for reservoir modelling and ensuring realism and coherence across all projected variables.
东海岸气候变化倡议(ESCCI)的一个主要目标是了解气候变化对澳大利亚东海岸的影响，以及对该地区适应气候变化的影响。新南威尔士州(NSW) /澳大利亚首都地区(ACT)区域气候模拟项目(NARCliM)产生了三个动态缩小尺度的再分析气候数据集，以及12个缩小尺度的环流模式(GCM)对当前(1990-2009)和未来气候的预测。预计NARCliM数据集将用于包括水安全评估在内的许多气候变化影响研究。因此，在本研究中，我们以Hunter water Corporation管理的Lower Hunter城市供水系统为例，对使用NARCliM数据进行水安全评估的有效性和局限性进行了案例研究。我们比较了使用NARCliM降雨和网格化历史降雨数据集(AWAP)模拟的河流流量和水库水位，并重点分析了模拟的河流流量和水库水位的差异。研究表明，当使用原始(即未经偏差校正的)NARCliM降雨和潜在蒸散(PET)数据来模拟河流和水库蓄水量时，与使用AWAP模拟相比，一些NARCliM数据集产生的结果不现实;例如，一些NARCliM数据集模拟的储层处于或接近空区，而AWAP储层模拟很少低于60%。经过偏差校正的NARCliM降雨量(校正为AWAP)产生的河流流量和水库水位估算值与直接使用AWAP模拟的河流流量和水库水位更接近，但仍然不一致。使用偏差校正降雨量的模拟与历史AWAP降雨量之间的不一致可能是因为虽然偏差校正减少了系统偏差，但它并没有解决时间降雨顺序问题。此外，NARCliM PET没有进行偏差校正，在水文模型中使用偏差校正的降雨量和未校正的PET会导致降雨量-PET关系和模拟水流的物理不一致。研究表明，降雨在径流模拟中起着重要作用，而PET通过确定水库的蒸发损失，似乎在模拟水库动力学的合理性中起着重要作用。缩小后的GCM数据集模拟了1990-2009年的最大平均PET，显示水库通常(不切实际地)接近于空。这项研究强调了评估所有气候数据有效性的必要性，重点是水库建模的长期统计数据，并确保所有预测变量的真实性和一致性。
{"title":"Case study on the use of dynamically downscaled climate model data for assessing water security in the Lower Hunter region of the eastern seaboard of Australia","authors":"Natalie Lockart, Garry Willgoose, George Kuczera, Anthony S. Kiem, AFM Kamal Chowdhury, Nadeeka Parana Manage, Lanying Zhang, Callum Twomey","doi":"10.1071/es16015","DOIUrl":"https://doi.org/10.1071/es16015","url":null,"abstract":"A key aim of the Eastern Seaboard Climate Change Initiative (ESCCI) is under-standing the effect of climate change on the eastern seaboard of Australia, and the implications for climate change adaptation in this area. The New South Wales (NSW) / Australian Capital Territory (ACT) Regional Climate Modelling project (NARCliM) has produced three dynamically downscaled reanalysis climate datasets along with 12 downscaled general circulation model (GCM) projections of current (1990–2009) and future climate. It is expected that the NARCliM dataset will be used for many climate change impact studies including water security assessment. Therefore, in this study we perform a case study investigation into the usefulness and limitations of using NARCliM data for water security assessment, using the Lower Hunter urban water supply system managed by Hunter Water Corporation. We compare streamflow and reservoir levels simulated using NARCliM rainfall and a gridded historical rainfall dataset (AWAP) and focus our analysis on the differences in the simulated streamflow and reservoir levels. We show that when raw (i.e. not bias-corrected) NARCliM rainfall and potential evapotranspiration (PET) data is used to simulate streamflow and reservoir storage levels, some of the NARCliM datasets produce unrealistic results when compared with the simulations using AWAP; for example, some NARCliM datasets simulate reservoirs at or near empty while the AWAP reservoir simulations rarely drop below 60%. The bias-corrected NARCliM rainfall (corrected to AWAP) produces estimates of streamflow and reservoir levels that have a closer, but still inconsistent, match with the streamflow and reservoir levels simulated using AWAP directly. The inconsistency between the simulations using bias-corrected rainfall and historical AWAP rainfall is potentially because while bias-correction reduces systematic deviations it does not fix temporal rainfall sequencing issues. Additionally, the NARCliM PET is not bias-corrected and using bias-corrected rainfall with uncorrected PET in hydrological models results in physical inconsistencies in the rainfall-PET relationship and simulated streamflow. We demonstrate that rainfall plays a large role in the streamflow simulations, while PET seems to play a large role in the reasonableness of the simulated reservoir dynamics by determining the evaporation losses from the reservoirs. The downscaled GCM datasets that simulate the greatest average PET for 1990–2009 show reservoirs often (unrealistically) near empty. This study highlights the need to assess the validity of all climate data for the applications required, with a focus on long-term statistics for reservoir modelling and ensuring realism and coherence across all projected variables.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"91 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543071","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Timothy Brown, Graham Mills, Sarah Harris, Domagoj Podnar, Hauss Reinbold, Matt Fearon
Climatology data of fire weather across the landscape can provide science-based evidence for informing strategic decisions to ameliorate the impacts (at times extreme) of bushfires on community socio-economic wellbeing and to sustain ecosystem health and functions. A long-term climatology requires spatial and temporal data that are consistent to represent the landscape in sufficient detail to be useful for fire weather studies and management purposes. To address this inhomogeneity problem for analyses of a variety of fire weather interests and to provide a dataset for management decision-support, a homogeneous 41-year (1972-2012), hourly interval, 4 km gridded climate dataset for Victoria has been generated using a combination of mesoscale modelling, global reanalysis data, surface observations, and historic observed rainfall analyses. Hourly near-surface forecast fields were combined with Drought Factor (DF) fields calculated from the Australian Water Availability Project (AWAP) rainfall analyses to generate fields of hourly fire danger indices for each hour of the 41-year period. A quantile mapping (QM) bias correction technique utilizing available observations during 1996-2012 was used to ameliorate any model biases in wind speed, temperature and relative humidity. Extensive evaluation was undertaken including both quantitative and case study qualitative assessments. The final dataset includes 4-km surface hourly temperature, relative humidity, wind speed, wind direction, Forest Fire Danger Index (FFDI), and daily DF and Keetch-Byram Drought Index (KBDI), and a 32-level full three-dimensional volume atmosphere.
{"title":"A bias corrected WRF mesoscale fire weather dataset for Victoria, Australia 1972-2012","authors":"Timothy Brown, Graham Mills, Sarah Harris, Domagoj Podnar, Hauss Reinbold, Matt Fearon","doi":"10.1071/es16020","DOIUrl":"https://doi.org/10.1071/es16020","url":null,"abstract":"Climatology data of fire weather across the landscape can provide science-based evidence for informing strategic decisions to ameliorate the impacts (at times extreme) of bushfires on community socio-economic wellbeing and to sustain ecosystem health and functions. A long-term climatology requires spatial and temporal data that are consistent to represent the landscape in sufficient detail to be useful for fire weather studies and management purposes. To address this inhomogeneity problem for analyses of a variety of fire weather interests and to provide a dataset for management decision-support, a homogeneous 41-year (1972-2012), hourly interval, 4 km gridded climate dataset for Victoria has been generated using a combination of mesoscale modelling, global reanalysis data, surface observations, and historic observed rainfall analyses. Hourly near-surface forecast fields were combined with Drought Factor (DF) fields calculated from the Australian Water Availability Project (AWAP) rainfall analyses to generate fields of hourly fire danger indices for each hour of the 41-year period. A quantile mapping (QM) bias correction technique utilizing available observations during 1996-2012 was used to ameliorate any model biases in wind speed, temperature and relative humidity. Extensive evaluation was undertaken including both quantitative and case study qualitative assessments. The final dataset includes 4-km surface hourly temperature, relative humidity, wind speed, wind direction, Forest Fire Danger Index (FFDI), and daily DF and Keetch-Byram Drought Index (KBDI), and a 32-level full three-dimensional volume atmosphere.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"106 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543127","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Felicity Gamble, Grant Beard, Andrew Watkins, David Jones, Catherine Ganter, Vanessa Webb, Alex Evans
Communicating the development of El Niño and La Niña events is often challenging, largely due to the general misconception that the transition to an event can occur rapidly – like flicking a switch. Additionally, in Australia the association of El Niño with drought, and La Niña with flood, and the impacts that result, can often cloud the message. The Australian Bureau of Meteorology is responsible for issuing updates on the current status of the El Niño-Southern Oscillation (ENSO), and declaring the onset and demise of an event. To assist in the communication of this often complex message, the Bureau of Meteorology developed an online tool, the ENSO Outlook, to keep stakeholders informed of the potential for El Niño or La Niña to develop in the upcoming seasons.
{"title":"Tracking the El Nino-Southern Oscillation in real-time: a staged communication approach to event onset","authors":"Felicity Gamble, Grant Beard, Andrew Watkins, David Jones, Catherine Ganter, Vanessa Webb, Alex Evans","doi":"10.1071/es17006","DOIUrl":"https://doi.org/10.1071/es17006","url":null,"abstract":"Communicating the development of El Niño and La Niña events is often challenging, largely due to the general misconception that the transition to an event can occur rapidly – like flicking a switch. Additionally, in Australia the association of El Niño with drought, and La Niña with flood, and the impacts that result, can often cloud the message. The Australian Bureau of Meteorology is responsible for issuing updates on the current status of the El Niño-Southern Oscillation (ENSO), and declaring the onset and demise of an event. To assist in the communication of this often complex message, the Bureau of Meteorology developed an online tool, the ENSO Outlook, to keep stakeholders informed of the potential for El Niño or La Niña to develop in the upcoming seasons.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"183 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138530425","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Mika Peace, Lachlan McCaw, Bradley Santos, Jeffrey D. Kepert, Neil Burrows, Robert J. B. Fawcett
The Waroona bushfire burnt 69,000 ha south of Perth in January 2016. During the first two days of the fire, there were two pyrocumulonimbus (pyroCb) events and two destructive evening fire runs. Over 160 homes were destroyed and there were two fatalities. This case study examines in detail the links between the meteorological observations and the fire behaviour reconstruction.The first pyroCb developed on Wednesday 6 January 2016, when the fire made an unexpectedly fast run in light prevailing winds. The pyroCb produced lightning strikes that ignited a new fire downwind of the main head fire. A second pyroCb developed on Thursday morning, against normal diurnal thunderstorm trends. Similar to the previous evening, the fire spread faster than expected, given the near-surface meteorological conditions.On both evenings there were destructive ember storms over the towns of Waroona (Wednesday) and Yarloop (Thursday). Examination of the meteorological observations has linked these ember showers to the onset of downslope winds, locally known as `scarp winds'. As downslope winds are associated with strong localised turbulence, they provide a mechanism for transport of large numbers of firebrands.The periods of extreme fire behaviour at Waroona were against normal diurnal expectations and did not coincide with the highest observed Fire Danger Index (FDI) values, which occurred at around 1600 LT. This study links both pyroCb events to accelerated fire spread, which presents a hazard to firefighters that is not accounted for in traditional, surface based methods of fire prediction. Downslope winds similar to those that impacted the Waroona fire occur at many locations. They provide a highly localised mechanism for destructive evening ember showers.This investigation into the Waroona fire describes the potential impacts of fireatmosphere feedback processes. Consequently, it highlights the need for predictive methods and tools that anticipate fire behaviour which is not steady-state. Planned simulations using a coupled fire-atmosphere model will allow further insights into features of this case study.
{"title":"Meteorological drivers of extreme fire behaviour during the Waroona bushfire, Western Australia, January 2016","authors":"Mika Peace, Lachlan McCaw, Bradley Santos, Jeffrey D. Kepert, Neil Burrows, Robert J. B. Fawcett","doi":"10.1071/es17007","DOIUrl":"https://doi.org/10.1071/es17007","url":null,"abstract":"The Waroona bushfire burnt 69,000 ha south of Perth in January 2016. During the first two days of the fire, there were two pyrocumulonimbus (pyroCb) events and two destructive evening fire runs. Over 160 homes were destroyed and there were two fatalities. This case study examines in detail the links between the meteorological observations and the fire behaviour reconstruction.The first pyroCb developed on Wednesday 6 January 2016, when the fire made an unexpectedly fast run in light prevailing winds. The pyroCb produced lightning strikes that ignited a new fire downwind of the main head fire. A second pyroCb developed on Thursday morning, against normal diurnal thunderstorm trends. Similar to the previous evening, the fire spread faster than expected, given the near-surface meteorological conditions.On both evenings there were destructive ember storms over the towns of Waroona (Wednesday) and Yarloop (Thursday). Examination of the meteorological observations has linked these ember showers to the onset of downslope winds, locally known as `scarp winds'. As downslope winds are associated with strong localised turbulence, they provide a mechanism for transport of large numbers of firebrands.The periods of extreme fire behaviour at Waroona were against normal diurnal expectations and did not coincide with the highest observed Fire Danger Index (FDI) values, which occurred at around 1600 LT. This study links both pyroCb events to accelerated fire spread, which presents a hazard to firefighters that is not accounted for in traditional, surface based methods of fire prediction. Downslope winds similar to those that impacted the Waroona fire occur at many locations. They provide a highly localised mechanism for destructive evening ember showers.This investigation into the Waroona fire describes the potential impacts of fireatmosphere feedback processes. Consequently, it highlights the need for predictive methods and tools that anticipate fire behaviour which is not steady-state. Planned simulations using a coupled fire-atmosphere model will allow further insights into features of this case study.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"80 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138530433","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Debra Hudson, Oscar Alves, Harry H. Hendon, Eun-Pa Lim, Guoqiang Liu, Jing-Jia Luo, Craig MacLachlan, Andrew G. Marshall, Li Shi, Guomin Wang, Robin Wedd, Griffith Young, Mei Zhao, Xiaobing Zhou
ACCESS-S1 will be the next version of the Australian Bureau of Meteorology's seasonal prediction system, due to become operational in early 2018. The multiweek and seasonal performance of ACCESS-S1 has been evaluated based on a 23-year hindcast set and compared to the current operational system, POAMA. The system has considerable enhancements compared to POAMA, including higher vertical and horizontal resolution of the component models and state-ofthe-art physics parameterisation schemes. ACCESS-S1 is based on the UK Met Office GloSea5-GC2 seasonal prediction system, but has enhancements to the ensemble generation strategy to make it appropriate for multi-week forecasting, and a larger ensemble size.ACCESS-S1 has markedly reduced biases in the mean state of the climate, both globally and over Australia, compared to POAMA. ACCESS-S1 also better predicts the early stages of the development of the El Niño Southern Oscillation (through the predictability barrier) and the Indian Ocean Dipole, as well as multi-week variations of the Southern Annular Mode and the Madden-Julian Oscillation — all important drivers of Australian climate variability. There is an overall improvement in the skill of the forecasts of rainfall, maximum temperature (Tmax) and minimum temperature (Tmin) over Australia on multi-week timescales compared to POAMA. On seasonal timescales the differences between the two systems are generally less marked. ACCESS-S1 has improved seasonal forecasts over Australia for the austral spring season compared to POAMA, with particularly good forecast reliability for rainfall and Tmax. However, forecasts of seasonal mean Tmax are noticeably less skilful over eastern Australia for forecasts of late autumn and winter compared to POAMA.The study has identified scope for improvement of ACCESS-S in the future, particularly 1) reducing rainfall errors in the Indian Ocean and Maritime Continent regions, and 2) initialising the land surface with realistic soil moisture rather than climatology. The latter impacts negatively on the skill of the temperature forecasts over eastern Australia and is being addressed in the next version of the system, ACCESS-S2.
{"title":"ACCESS-S1 The new Bureau of Meteorology multi-week to seasonal prediction system","authors":"Debra Hudson, Oscar Alves, Harry H. Hendon, Eun-Pa Lim, Guoqiang Liu, Jing-Jia Luo, Craig MacLachlan, Andrew G. Marshall, Li Shi, Guomin Wang, Robin Wedd, Griffith Young, Mei Zhao, Xiaobing Zhou","doi":"10.1071/es17009","DOIUrl":"https://doi.org/10.1071/es17009","url":null,"abstract":"ACCESS-S1 will be the next version of the Australian Bureau of Meteorology's seasonal prediction system, due to become operational in early 2018. The multiweek and seasonal performance of ACCESS-S1 has been evaluated based on a 23-year hindcast set and compared to the current operational system, POAMA. The system has considerable enhancements compared to POAMA, including higher vertical and horizontal resolution of the component models and state-ofthe-art physics parameterisation schemes. ACCESS-S1 is based on the UK Met Office GloSea5-GC2 seasonal prediction system, but has enhancements to the ensemble generation strategy to make it appropriate for multi-week forecasting, and a larger ensemble size.ACCESS-S1 has markedly reduced biases in the mean state of the climate, both globally and over Australia, compared to POAMA. ACCESS-S1 also better predicts the early stages of the development of the El Niño Southern Oscillation (through the predictability barrier) and the Indian Ocean Dipole, as well as multi-week variations of the Southern Annular Mode and the Madden-Julian Oscillation — all important drivers of Australian climate variability. There is an overall improvement in the skill of the forecasts of rainfall, maximum temperature (Tmax) and minimum temperature (Tmin) over Australia on multi-week timescales compared to POAMA. On seasonal timescales the differences between the two systems are generally less marked. ACCESS-S1 has improved seasonal forecasts over Australia for the austral spring season compared to POAMA, with particularly good forecast reliability for rainfall and Tmax. However, forecasts of seasonal mean Tmax are noticeably less skilful over eastern Australia for forecasts of late autumn and winter compared to POAMA.The study has identified scope for improvement of ACCESS-S in the future, particularly 1) reducing rainfall errors in the Indian Ocean and Maritime Continent regions, and 2) initialising the land surface with realistic soil moisture rather than climatology. The latter impacts negatively on the skill of the temperature forecasts over eastern Australia and is being addressed in the next version of the system, ACCESS-S2.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"34 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543078","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pilar A. Barria, Murray C. Peel, Kevin J.E. Walsh, René Garreaud
Streamflow reductions have been reported in mid-latitude Southern Hemisphere (SH) catchments, in particular in the southwest of Western Australia (SWA) and in central Chile (CC), following decreases in precipitation since the mid-1970s. Although projections from Global Climate Models (GCMs) indicate the observed trends are expected to continue during the rest of the 21st century, they are affected by large uncertainties that challenge informed decision making. Quantification and comparison of uncertainties in runoff projections for the period 2050-2080 relative to 1970-2000, driven by an ensemble of a single GCM with perturbed physics (CPDN) and a multi-model ensemble of different GCMs (CMIP5), were used to account for what we term “within-GCM” and “between-GCM” uncertainty in SWA catchments. Between GCM uncertainty of runoff projections was also quantified in CC catchments. Within and between-GCM uncertainties were found to be very similar (∼55 per cent) in SWA catchments. Between-GCM uncertainty for runoff projections in CC catchments is smaller than in SWA. On average, uncertainty of about 51 per cent, under RCP8.5 scenario, was simulated for the period 2050-2080 compared to 1970-2000. For CC catchments a dichotomy was observed in runoff projections under the RCP4.5 scenario, which according to our preliminary analysis might relate to how ozone is specified within different GCMs. We conclude that the number of models sampled by the CMIP5 ensemble, which includes multiple model runs from some GCMs, provides some insight into within-GCM uncertainties. Furthermore, since CMIP5 model runs report values for all regions and are easily accessible, the CMIP5 ensemble is more convenient for regional hydrological assessments than the perturbed physics experiments.
{"title":"Analysis of within and between-GCM uncertainties of runoff projections in Mediterranean-like catchments","authors":"Pilar A. Barria, Murray C. Peel, Kevin J.E. Walsh, René Garreaud","doi":"10.1071/es17011","DOIUrl":"https://doi.org/10.1071/es17011","url":null,"abstract":"Streamflow reductions have been reported in mid-latitude Southern Hemisphere (SH) catchments, in particular in the southwest of Western Australia (SWA) and in central Chile (CC), following decreases in precipitation since the mid-1970s. Although projections from Global Climate Models (GCMs) indicate the observed trends are expected to continue during the rest of the 21st century, they are affected by large uncertainties that challenge informed decision making. Quantification and comparison of uncertainties in runoff projections for the period 2050-2080 relative to 1970-2000, driven by an ensemble of a single GCM with perturbed physics (CPDN) and a multi-model ensemble of different GCMs (CMIP5), were used to account for what we term “within-GCM” and “between-GCM” uncertainty in SWA catchments. Between GCM uncertainty of runoff projections was also quantified in CC catchments. Within and between-GCM uncertainties were found to be very similar (∼55 per cent) in SWA catchments. Between-GCM uncertainty for runoff projections in CC catchments is smaller than in SWA. On average, uncertainty of about 51 per cent, under RCP8.5 scenario, was simulated for the period 2050-2080 compared to 1970-2000. For CC catchments a dichotomy was observed in runoff projections under the RCP4.5 scenario, which according to our preliminary analysis might relate to how ozone is specified within different GCMs. We conclude that the number of models sampled by the CMIP5 ensemble, which includes multiple model runs from some GCMs, provides some insight into within-GCM uncertainties. Furthermore, since CMIP5 model runs report values for all regions and are easily accessible, the CMIP5 ensemble is more convenient for regional hydrological assessments than the perturbed physics experiments.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"70 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138543077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Many agricultural studies have identified that wheat yield is sensitive to seasonal rainfall and extreme high temperatures. We investigate the impact of extreme heat events, in particular on wheat yields in South-East Australia (SEA) and South-West Western Australia (SWWA).We define a 'heat-day' as a day where the daily maximum temperature exceeds the 1911–2013 90th percentile for the respective calendar month. We find that the number of heat-days has experienced statistically significant increases across most months across much of Australia, particularly in South Australia, Western Australia, the Northern Territory and Tasmania. The trends are especially marked in winter, including in key wheat-growing regions. The temperatures recorded on these hottest days have also shown a statistically significant increase over the last 100 years.We find that, while wheat yields are more strongly correlated with rainfall than with the number of heat-days, there is substantial evidence to suggest that during drought conditions wheat yields are sensitive to the number of heat-days recorded in August and September in SEA and September and October in SWWA. Extreme heat and rainfall have a stronger association with below-average yields than above-average yields.Extreme temperatures and rainfall in these regions are related to major Australian climate drivers which form the basis of seasonal prediction models and are important for natural variability and long-term climate change. Here we assess the degree to which wheat yields in both regions can be related to the El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Southern Annular Mode (SAM). We find that positive IOD events and El Niño events are both associated with reductions in wheat yields in SEA, but that the co-incidence of these events have no additional wheat yield reductions than would be expected if either a positive IOD or El Niño event occurs. The average annual wheat yield loss associated with El Niño state and/or positive IOD state in SEA is estimated to around sixteen to twenty one per cent.This paper provides insights into the historical relationships between wheat yields, extreme heat and climatic modes of variability in Australia, and discusses the possibilities for changes in wheat yields under a future climate change scenario.
{"title":"Effects of heat extremes on wheat yields in Australia","authors":"Ben Hague, Karl Braganza, David Jones","doi":"10.1071/es16021","DOIUrl":"https://doi.org/10.1071/es16021","url":null,"abstract":"Many agricultural studies have identified that wheat yield is sensitive to seasonal rainfall and extreme high temperatures. We investigate the impact of extreme heat events, in particular on wheat yields in South-East Australia (SEA) and South-West Western Australia (SWWA).We define a 'heat-day' as a day where the daily maximum temperature exceeds the 1911–2013 90th percentile for the respective calendar month. We find that the number of heat-days has experienced statistically significant increases across most months across much of Australia, particularly in South Australia, Western Australia, the Northern Territory and Tasmania. The trends are especially marked in winter, including in key wheat-growing regions. The temperatures recorded on these hottest days have also shown a statistically significant increase over the last 100 years.We find that, while wheat yields are more strongly correlated with rainfall than with the number of heat-days, there is substantial evidence to suggest that during drought conditions wheat yields are sensitive to the number of heat-days recorded in August and September in SEA and September and October in SWWA. Extreme heat and rainfall have a stronger association with below-average yields than above-average yields.Extreme temperatures and rainfall in these regions are related to major Australian climate drivers which form the basis of seasonal prediction models and are important for natural variability and long-term climate change. Here we assess the degree to which wheat yields in both regions can be related to the El Niño Southern Oscillation (ENSO), Indian Ocean Dipole (IOD) and Southern Annular Mode (SAM). We find that positive IOD events and El Niño events are both associated with reductions in wheat yields in SEA, but that the co-incidence of these events have no additional wheat yield reductions than would be expected if either a positive IOD or El Niño event occurs. The average annual wheat yield loss associated with El Niño state and/or positive IOD state in SEA is estimated to around sixteen to twenty one per cent.This paper provides insights into the historical relationships between wheat yields, extreme heat and climatic modes of variability in Australia, and discusses the possibilities for changes in wheat yields under a future climate change scenario.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"12 1","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138530424","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Subtropical maritime low-pressure systems are one of the most complex and destructive storm types to impact Australia’s eastern seaboard. This family of storms, commonly referred to as East Coast Cyclones (ECC), is most active during the late autumn and early winter period when baroclinicity increases in the Tasman Sea region. ECC have proven challenging to forecast at both event and seasonal timescales. Storm activity datasets, objectively determined from reanalyses using cyclone detection algorithms, have improved understanding of the drivers of ECC over the era of satellite data coverage. In this study we attempt to extend these datasets back to 1851 using the Twentieth Century Reanalysis version 2c (20CRv2c). However, uncertainty in the 20CRv2c increases back through time due to observational data scarcity, and individual cyclones counts tend to be underestimated during the 19th century. An alternative approach is explored whereby storm activity is estimated from seasonal atmosphere-ocean circulation patterns. Seasonal ECC frequency over the 1955 to 2014 period is significantly correlated to regional sea-level pressure and sea surface temperature (SST) patterns. These patterns are used to downscale the 20CRv2c during early years when individual events are not well simulated. The stormiest periods since 1851 appear to have been 1870 to the early 1890s, and 1950 to the early 1970s. Total storm activity has been below the long-term average for most winters since 1976. Conditions conducive to frequent ECC events tend to occur during periods of relatively warm SST in the southwest Pacific typical of negative Interdecadal Pacific Oscillation (IPO-ve). Extratropical cyclogenesis is associated with negative Southern Annular Mode (SAM-ve) and blocking in the southern Tasman Sea. Subtropical cyclogenesis is associated with SAM+ve and blocking in the central Tasman Sea. While the downscaling approach shows some skill at estimating seasonal storm activity from the large-scale circulation, it cannot overcome data scarcity based uncertainties in the 19th century when the 20CRv2c is effectively unconstrained throughout most of the southern hemisphere. Storm frequency estimates during the 19th century are difficult to verify and should be interpreted cautiously and with reference to available documentary evidence.
{"title":"Large-scale drivers of Australian east coast cyclones since 1851","authors":"Stuart A. Browning, Ian D. Goodwin","doi":"10.1071/es16012","DOIUrl":"https://doi.org/10.1071/es16012","url":null,"abstract":"Subtropical maritime low-pressure systems are one of the most complex and destructive storm types to impact Australia’s eastern seaboard. This family of storms, commonly referred to as East Coast Cyclones (ECC), is most active during the late autumn and early winter period when baroclinicity increases in the Tasman Sea region. ECC have proven challenging to forecast at both event and seasonal timescales. Storm activity datasets, objectively determined from reanalyses using cyclone detection algorithms, have improved understanding of the drivers of ECC over the era of satellite data coverage. In this study we attempt to extend these datasets back to 1851 using the Twentieth Century Reanalysis version 2c (20CRv2c). However, uncertainty in the 20CRv2c increases back through time due to observational data scarcity, and individual cyclones counts tend to be underestimated during the 19th century. An alternative approach is explored whereby storm activity is estimated from seasonal atmosphere-ocean circulation patterns. Seasonal ECC frequency over the 1955 to 2014 period is significantly correlated to regional sea-level pressure and sea surface temperature (SST) patterns. These patterns are used to downscale the 20CRv2c during early years when individual events are not well simulated. The stormiest periods since 1851 appear to have been 1870 to the early 1890s, and 1950 to the early 1970s. Total storm activity has been below the long-term average for most winters since 1976. Conditions conducive to frequent ECC events tend to occur during periods of relatively warm SST in the southwest Pacific typical of negative Interdecadal Pacific Oscillation (IPO-ve). Extratropical cyclogenesis is associated with negative Southern Annular Mode (SAM-ve) and blocking in the southern Tasman Sea. Subtropical cyclogenesis is associated with SAM+ve and blocking in the central Tasman Sea. While the downscaling approach shows some skill at estimating seasonal storm activity from the large-scale circulation, it cannot overcome data scarcity based uncertainties in the 19th century when the 20CRv2c is effectively unconstrained throughout most of the southern hemisphere. Storm frequency estimates during the 19th century are difficult to verify and should be interpreted cautiously and with reference to available documentary evidence.","PeriodicalId":55419,"journal":{"name":"Journal of Southern Hemisphere Earth Systems Science","volume":"47 2","pages":""},"PeriodicalIF":3.6,"publicationDate":"2021-08-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"138509316","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
京公网安备 11010802042870号
京ICP备2023020795号-1
扫码关注我们
求助内容：
应助结果提醒方式：