Developing a variable resolution Regional Earth System Model (RESM) for Australia

Dr Marcus Thatcher1, Dr John McGregor1, Dr Jack Katzfey1

1CSIRO Oceans and Atmosphere, Aspendale, Australia


Regional Earth System Models (RESMs) are starting to replace traditional Regional Climate Models (RCMs) for studying the impacts of a changing climate at regional spatial scales.  Although RCMs focus on physical atmospheric dynamics and processes, RESMs also include oceans, sea-ice, rivers, aerosols, land-cover changes, carbon cycle and other components of the Earth system.  This presentation describes the development of a variable resolution RESM based on the CSIRO’s Conformal Cubic Atmospheric Model (CCAM), which allows for higher resolution over a region but without requiring lateral boundary conditions used by limited area models.

RESMs can potentially require considerable high-performance computing to simulate the various Earth system components over climate time-scales (e.g., 100+ years) while resolving high temporal and spatial detail (e.g., minutes for scales of a few kilometres).  This presentation outlines the design of the new CCAM-RESM including a combined atmosphere-ocean model that allows for rapid atmosphere-ocean interactions, the Australian community CABLE and CASA-CNP model for changes in the land-use and carbon cycle, prognostic aerosols consistent with Shared Socioeconomic Pathways for the next generation of climate projections.  Components being developed for urban energy use and for simple river routing will also be discussed.

Applications of the CCAM-RESM will be shown including a 12 km simulation for Australia that can produce more than 5.8 simulation years per day on 1,944 Cascadelake cores in single precision mode at NCI’s Gadi supercomputer, which is faster than most existing RCMs.  Plans for transitioning to general purpose GPUs will also be described.


Marcus Thatcher has developed regional climate models at CSIRO Oceans and Atmosphere for the last 15 years.  He leads the Extreme Weather and Climate team at the Climate Science Center.


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