Links between East Coast Lows and the spatial and temporal variability of rainfall along the eastern seaboard of Australia

Kiem, Anthony S.; Twomey, Callum; Lockart, Natalie; Willgoose, Garry; Kuczera, George; Chowdhury, Afm Kamal; Manage, Nadeeka Parana; Zhang, Lanying

doi:10.22499/3.6002.006

“…A direction of further investigation is to assess how the impacts of different classes of ECLs such as hybrid or cold-core cyclones differ, in terms of wind, rainfall, or other variables along the lines of a similar analysis of Kiem et al (2016) for cyclones with a different origin.…”

Section: B Conclusion and Outlookmentioning

confidence: 99%

“…One aspect is whether climate change will affect different classes of low pressure systems in similar or different ways (e.g., by altering the relative fraction or the spatial patterns of warm-core, hybrid, and cold-core systems). Such alteration can cause changes in the associated impacts if the impacts of different classes of cyclones differ substantially (Kiem et al 2016). Furthermore, there are several indications of a poleward migration of tropical cyclone activity following the expansion of the tropics in a warmer climate (Walsh and Katzfey 2000;Lavender and Walsh 2011;Kossin et al 2014;Parker et al 2018;Studholme and Gulev 2018;Sharmila and Walsh 2018).…”

Section: B Conclusion and Outlookmentioning

confidence: 99%

A Physically Based Climatology of the Occurrence and Intensification of Australian East Coast Lows

Cavicchia

¹

,

Pepler

²

,

Dowdy

³

et al. 2019

View full text Add to dashboard Cite

The subtropical part of the eastern Australian seaboard experiences intense cyclonic activity. The severe damage caused by the intense storms in the region, known as east coast lows (ECLs), has motivated a number of recent studies. Cyclones in this region appear to be driven by a combination of different (barotropic and baroclinic) formation mechanisms, consistent with the view emerging in the last decades that cyclones span a continuous spectrum of dynamical structures, with the barotropically driven tropical cyclone and the baroclinically driven extratropical cyclone being only the extremes of such a spectrum. In this work we revisit the climatology of cyclone occurrence in the subtropical east coast of Australia as seen in a global reanalysis, systematically applying classification criteria based on the cyclone vertical structure and thermal core. Moreover, we investigate the underlying processes driving the cyclone rapid intensification by means of an atmospheric limited-area energetics analysis. We show that ECLs have different spatial patterns according to the cyclone thermal structure, with the fraction of hybrid cyclones being larger toward the tropics and closer to the coast. Moreover, we find that explosively deepening cyclones in this region are driven by a different combination of processes with respect to the global case, with barotropic processes in the surrounding environment having a more dominant role in the energetics of cyclone rapid intensification. The findings of this work contribute to understanding the physical processes underlying the formation and intensification of Australian east coast lows and the associated coastal damage and risk.

show abstract

“…This study will not explicitly look at ECL impacts on water security but we reference ECL dynamics as motivation for this study. Kiem et al (2016) describes these dynamics.…”

Section: Introductionmentioning

confidence: 99%

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

Lockart¹,

Willgoose²,

Kuczera³

et al. 2016

JSHESS

Self Cite

View full text Add to dashboard Cite

A key aim of the Eastern Seaboard Climate Change Initiative (ESCCI) is understanding 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)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(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 simuLockart. Dynamically downscaled climate model data for assessing water security 178 late 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.

show abstract

“…Investigate ECL formation, impacts, historical variability and future projections (see Kiem et al 2016). 2.…”

Section: Introductionmentioning

confidence: 99%

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

Lockart¹,

Willgoose²,

Kuczera³

et al. 2016

JSHESS

Self Cite

View full text Add to dashboard Cite

A key aim of the Eastern Seaboard Climate Change Initiative (ESCCI) is understanding 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)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005)(2006)(2007)(2008)(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 simuLockart. Dynamically downscaled climate model data for assessing water security 178 late 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.

show abstract

Links between East Coast Lows and the spatial and temporal variability of rainfall along the eastern seaboard of Australia

Cited by 12 publications

References 10 publications

A Physically Based Climatology of the Occurrence and Intensification of Australian East Coast Lows

A Physically Based Climatology of the Occurrence and Intensification of Australian East Coast Lows

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

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

Contact Info

Product

Resources

About