Upcoming Events
29 Apr (CLIM) Annamalai, Unprecedented South Asia Extremes
Apr 29, 2025, 1:30 - 2:30 PM
H. Annamalai, U Hawaii
Monsoon-induced unprecedented extremes over driest regions of South Asia:
Process-based understanding of the Pakistan flood of 2022
Tue, 29 Apr, 1:30pm – note special day
“Exploratory 1309 and via Zoom (for link, email bklinger@gmu.edu)
Host: Jim Kinter
During the 2022 Asian summer monsoon, the climatological driest parts of southwestern Pakistan and the northern Arabian Sea (regions of climatological heat low, HLOW) experienced unprecedented precipitation (>500% of the normal) whereas precipitation was reduced from the Indo-Gangetic Plain to the tropical western Pacific. Its causes are examined with process-oriented diagnostics applied to reanalysis (ERA5), and numerical experiments with a linear atmospheric general circulation model. Model solutions confirm that the weakened large-scale monsoon is determined by warm SST and enhanced precipitation over the eastern Indian Ocean and Maritime Continent. Rossby waves from those regions then deepen the HLOW. The resultant horizontal pressure gradient between HLOW and northern India drives low-level wind anomalies that precondition the lower troposphere during June, and drive the unprecedented precipitation during July–August. We will also discuss the monsoon response to nearly identical tropical forcing observed during 2010 and 2020, and the monsoon response over southwest Pakistan.
