Biological and Environmental Research - Earth and Environmental System Sciences
Earth and Environmental System Modeling

The Decadal Reduction of Southeastern Australian Autumn Rainfall since the Early 1990s: A Response to Sea Surface Temperature Warming in the Subtropical South Pacific

TitleThe Decadal Reduction of Southeastern Australian Autumn Rainfall since the Early 1990s: A Response to Sea Surface Temperature Warming in the Subtropical South Pacific
Publication TypeJournal Article
Year of Publication2020
JournalJournal of Climate
Volume33
Number6
Pages2249-2261
Abstract / Summary

Rainfall in southeastern Australia (SEA) decreased substantially in the austral autumn (March–May) of the 1990s and 2000s. The observed autumn rainfall reduction has been linked to the climate change–induced poleward shift of the subtropical dry zone across SEA and natural multidecadal variations. However, the underlying physical processes responsible for the SEA drought are still not fully understood. This study highlights the role of sea surface temperature (SST) warming in the subtropical South Pacific (SSP) in the autumn rainfall reduction in SEA since the early 1990s. The warmer SSP SST enhances rainfall to the northwest in the southern South Pacific convergence zone (SPCZ); the latter triggers a divergent overturning circulation with the subsidence branch over the eastern coast of Australia. As such, the subsidence increases the surface pressure over Australia, intensifies the subtropical ridge, and reduces the rainfall in SEA. This mechanism is further confirmed by the result of a sensitivity experiment using an atmospheric general circulation model. Moreover, this study further indicates that global warming and natural multidecadal variability contribute approximately 44% and 56%, respectively, of the SST warming in the SSP since the early 1990s.

URLhttp://dx.doi.org/10.1175/jcli-d-19-0686.1
DOI10.1175/jcli-d-19-0686.1
Journal: Journal of Climate
Year of Publication: 2020
Volume: 33
Number: 6
Pages: 2249-2261
Publication Date: 03/2020

Rainfall in southeastern Australia (SEA) decreased substantially in the austral autumn (March–May) of the 1990s and 2000s. The observed autumn rainfall reduction has been linked to the climate change–induced poleward shift of the subtropical dry zone across SEA and natural multidecadal variations. However, the underlying physical processes responsible for the SEA drought are still not fully understood. This study highlights the role of sea surface temperature (SST) warming in the subtropical South Pacific (SSP) in the autumn rainfall reduction in SEA since the early 1990s. The warmer SSP SST enhances rainfall to the northwest in the southern South Pacific convergence zone (SPCZ); the latter triggers a divergent overturning circulation with the subsidence branch over the eastern coast of Australia. As such, the subsidence increases the surface pressure over Australia, intensifies the subtropical ridge, and reduces the rainfall in SEA. This mechanism is further confirmed by the result of a sensitivity experiment using an atmospheric general circulation model. Moreover, this study further indicates that global warming and natural multidecadal variability contribute approximately 44% and 56%, respectively, of the SST warming in the SSP since the early 1990s.

DOI: 10.1175/jcli-d-19-0686.1
Citation:
Lin, Z, Y Li, Y Liu, and A Hu.  2020.  "The Decadal Reduction of Southeastern Australian Autumn Rainfall since the Early 1990s: A Response to Sea Surface Temperature Warming in the Subtropical South Pacific."  Journal of Climate 33(6): 2249-2261.  https://doi.org/10.1175/jcli-d-19-0686.1.