Regional climate modelling plays a central role in understanding and projecting climate change across Australasia, a region characterised by complex topography, diverse climate regimes, and high exposure to climate extremes. Over the past fifteen years, CORDEX-Australasia has coordinated regional climate downscaling under an international framework while operating alongside complementary national and state-based initiatives. Here we synthesise the evolution, achievements, scientific advances, applications, and future priorities of regional climate modelling in the region. Successive CORDEX-CMIP5 and CORDEX-CMIP6 ensembles have produced the largest coordinated high-resolution projection datasets for Australasia. Regional climate models demonstrate clear added value over their driving global climate models, particularly in representing temperature extremes, heavy precipitation, coastal processes, and complex terrain. CMIP6-based projections show robust agreement on substantial 21st-century warming, with uncertainty dominated by emissions scenarios, while precipitation responses remain more regionally heterogeneous. Advances in convection-permitting modelling, benchmarking frameworks, and bias-correction methods have further improved process representation and evaluation. Regional projections now underpin applications in water resources, agriculture, disaster risk reduction, energy, health, and national climate services. Progress has been supported by shared infrastructure through the National Computational Infrastructure and strengthened coordination via the National Partnership for Climate Projections, highlighting strong synergies between State and Federal programs contributing to CORDEX. Key challenges remain including computational demands, persistent model biases, precipitation uncertainty, ensemble design, and translating complex multi-model information into decision-ready guidance. Strategic priorities include kilometre-scale (convection-permitting) modelling, enhanced Earth system coupling, coordinated super-ensembles, responsible integration of artificial intelligence approaches, strengthened observational constraints, and expanded support for vulnerable remote Australian islands and Pacific Island nations. Sustained investment, collaboration, and innovation will be essential to deliver robust, high-resolution climate information for adaptation and resilience across Australasia.
J. Evans, Marcus Thatcher, Daniel Argüeso et al.· PLOS Climate· 0 citations
Tropical cyclones (TCs) cause major economic losses in Australia due to severe winds and floods; however global climate models (GCMs) are too coarse to properly resolve them. Here, we dynamically downscale ERA5 reanalysis and 16 CMIP6 simulations from 11 GCMs using the Conformal Cubic Atmospheric Model (CCAM) to a ∼10 km resolution over the Australian region. We evaluate whether these simulations can represent TC activity over the Australian region by analyzing TC frequency, genesis, intensity, lifespan, and the role of ocean–atmosphere coupling. The downscaled simulations reproduce observed spatial and seasonal patterns of TC activity, with the highest skill in the central and eastern subregions. CCAM‐ERA5 captures the observed intensity distribution for Categories 2–4 and the relationship between lifespan and intensity. The CCAM‐CMIP6 ensemble reproduces mean TC number well in the central and eastern subregions but underestimates the most intense (Categories 4–5) and medium‐lived TCs (6–8 days) while overestimating Category 1 systems. Ocean coupling has model‐dependent effects rather than producing a systematic improvement. Coupled configurations generally simulate fewer TCs than atmosphere‐only configurations, mainly through reduced weak‐TC numbers, while differences in stronger‐TC intensity are generally small and metric dependent. Overall, the CCAM downscaled simulations provide a realistic representation of Australian TC climatology, particularly in the central and eastern subregions, but remaining biases in the western basin and in the upper tail of TC intensity should be considered in future projection and impact applications.
Xiao-Cheng Yu, Jozef I. Syktus, R. Trancoso et al.· Journal of Geophysical Resea...· 0 citations
Longevity of the Great Barrier Reef (GBR) relies on specific oceanic and atmospheric conditions that are quickly deteriorating under climate change. While global climate models (GCMs) provide insights into large‐scale processes, they often lack the resolution to capture regional nuances affecting the GBR. Similarly, regional climate models (RCMs) are hindered by the complexity of atmosphere‐ocean interactions and potential biases in the representation of global processes in the regional domain. Here, we present a large ensemble of Conformal Cubic Atmospheric Model (CCAM) simulations that address challenges in GCMs and RCMs with various configurations in stretched grids, bias‐corrected SST forcings, spectral nudging and atmosphere‐ocean coupling and test the roles of model configurations in high‐resolution ocean temperature simulations. Near surface temperature (NST) and sea surface temperature (SST) were simulated at approximately 10 km resolutions and used to estimate heat stress with the Degree Heating Weeks (DHW), a commonly used thermal anomaly metric for coral reef ecosystems. Model performance was assessed using the Perkins skill score (PSS) and bias relative to observations. Model bias was significantly reduced throughout the year across the entire GBR when the models were both atmosphere‐ocean coupled and prescribed bias‐corrected SSTs. The same configuration also improved model performance in simulating extreme temperatures and DHW estimation across the GBR. Atmosphere‐ocean coupling without prescribed bias‐corrected SSTs showed considerable cold bias and reduced performance in the central and southern GBR. The improvements to high‐resolution ocean temperature simulations and heat stress estimations set an important benchmark to assess changing hazards across the GBR.
Sun W. Kim, Jozef I. Syktus, Marcus Thatcher et al.· Journal of Geophysical Resea...· 0 citations
Understanding how precipitation is associated with the atmospheric features is critical for comprehension of processes underpinning water resource management and extreme events leading to natural disasters. This study evaluates how the key atmospheric features of Australia are associated to total and extreme precipitation across eight Australian natural resource management regions and how they vary seasonally. To this end, we apply the Multi-Object Analysis of Atmospheric Phenomena algorithm to two reanalysis datasets—ERA5 and BARRA-R2—and assess feature frequency and precipitation contributions for the period 1980–2020. Results show strong regional and seasonal differences. Precipitation often occurs together with jet streams, mesoscale convective systems, atmospheric rivers and cyclones. Extreme precipitation is closely linked to mesoscale convective systems and cyclones in northern Australia, particularly during warm season, while in southern Australia it is primarily driven by jet streams, cyclones, and atmospheric rivers, noting uncertainties for fronts. Trend analysis reveals opposite shifts in jet streams, mesoscale convective systems and atmospheric rivers across regions and seasons, with increases over southern and central regions during warm season and decreases for east, south and west regions during cool season. This study provides the first multi-feature assessment of atmospheric drivers of Australian precipitation, using a complementary approach to previous studies, offering valuable insights for climate adaptation and water resource management.
Shaoxiu Ma, R. Trancoso, Jozef I. Syktus et al.· Environmental Research Commu...· 0 citations
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