Exploring differing southern Australian rainfall projections in ACCESS-ESM1.5 and CM2
Peter Dobrohotoff
Two ACCESS models, ACCESS-ESM1.5 (ESM1.5) and ACCESS-CM2 (CM2), were submitted to CMIP6. While the models are in many ways similar, high-emissions, concentration-driven experiments in ESM1.5 generally produce drier rainfall anomalies over Australia than does CM2, and ESM1.5 is one of the driest models in a multi-model intercomparison. Here we explore this difference over southern Australia and find that while both models exhibit a positive trend in the Southern Annular Mode in a warming climate, shifting storm tracks further south of the continent, the impact of the thermodynamics appears to differ between the two: we show significantly higher soil drying in ESM1.5, which may be involved in a land-atmosphere feedback that reduces evapotranspiration, providing less humidity locally for precipitation.
Peter Dobrohotoff (CSIRO), Harun Rashid (CSIRO), Siobhan O’Farrell (CSIRO), Rachel Law (CSIRO), Ian Harman (CSIRO), Tilo Ziehn (CSIRO)
Keywords: regional climate change, rainfall trends, CMIP6, moisture transport, dynamics, thermodynamics
Audience: model development, climate impacts, atmospheric dynamics, land-atmosphere thermodynamics
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