The role of Indo-Pacific SST variability in global drought occurrence
Georgina Falster
1. Sea surface temperature (SST) variability in the tropical Indian and Pacific oceans impacts the occurrence, duration, and intensity of droughts across the mid-latitudes. Palaeoclimate evidence suggests that in the first half of the last millennium, a ~30% reduction in the magnitude of Indo-Pacific SST variability (e.g., ENSO, IOD) coincided with increased frequency of multi-decade ‘megadroughts’ across the mid-latitudes. However, megadroughts are too rare even in the palaeoclimate record to test the robustness of this relationship.
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We used ACCESS-ESM1.5 to examine the relationship between tropical Indo-Pacific SST variability and mid-latitude drought. We ran ACCESS-ESM1.5 with tropical Indo-Pacific SST variability prescribed to be 60% reduced, 30% reduced, 30% increased, or 60% increased relative to the existing ACCESS-ESM1.5 preindustrial control (500 years each).
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The experiments were still running at the time of submission. A crude preliminary analysis indicates that drought length and intensity around south-eastern Australia is greater in the simulations with Indo-Pacific SST variability increased or reduced by 30% relative to the preindustrial. Increasing the magnitude of change to 60% in either direction resulted in shorter and less intense droughts.
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ENSO and IOD enthusiasts, drought researchers, palaeoclimate researchers
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ACCESS-ESM1.5, ENSO, IOD, drought, Australian hydroclimate
Please use this thread for discussion about this plenary talk.