UW-AOS Colloquium - October 31 2022 - Dr. Akshaya Nikumbh

Speaker: Dr. Akshaya Nikumbh - Postdoc at Princeton/GFDL
Title: How are heavy rainfall events of different spatial extents triggered over India?
Abstract: The spatial extent of heavy rainfall events has been less explored in the literature, even though it directly affects damages and impacts caused by such events. In this talk, I will discuss how considering the spatial extent (size) of heavy rainfall events while defining them adds more insights into their observed trends and the underlying physical processes. Our analysis shows that the average size of rainfall extremes over Central India is increasing significantly. It is the size rather than the frequency of rainfall extremes that explains their increase over Central India after 1990. This reveals the changing spatial characteristics of rainfall extremes over the study region that was not noted before. To get a mechanistic view of events of different sizes, we classify them as small, medium and large events. A majority of these events are associated with synoptic-scale monsoon low-pressure systems but are accompanied by different large-scale background conditions. I will discuss mechanisms that control the spatial extent of heavy rainfall events when produced by monsoon lows. Finally, I will briefly touch upon tropical-extratropical interactions during the boreal summer monsoon and their influence on large events.