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Mountains and rainfall



Rainfall properties vary on short distances. In particular, mountains create sharp precipitation gradients. During the Indian monsoon, the Himalayas function as a barrier that shields the arid interior of the Tibetan Plateau from intense convection along the Gangetic Plain and Himalayan Foothills. From the lens of geophysical fluid dynamics, we expect even low topography to alter atmospheric flow. However, it is unclear whether other nearby high terrain blocks monsoonal flow or permits it. My thesis focuses in particular on the role of the Yunnan Plateau (right) in separating or linking the Indian and East Asian summer monsoons.



"South Flood North Drought"



A growing volume of evidence points to a significant shift in mean rainfall in China beginning in the late 1970s (the "70s shift"), with worsened flooding along the Yangtze River and droughts in northern China. Such changes have a massive impact on one of the most densely populated regions of the world. In response, the Chinese government is undertaking one of the most expensive engineering projects ever to divert water from the Yangtze River northward (the "South-North Water Transfer Project" or 南水北调工程, as discussed in the New York Times.

Current studies have attributed the pattern either to human influence (aerosols) or natural variability. China features an unusual spring peak season of rainfall, the Meiyu (梅雨, "plum rains," or jokingly 霉雨 "mold rains" due to their after-effect), featuring a persistent but migrating front between warm, moist air from the South China Sea and cold, dry air from the continental interior. Using observational data, I aim to quantify the interannual variability of rainfall during Meiyu season, and collocate its variability with that of other atmospheric processes, with the goal of determining the physical origin of the "South Flood North Drought" pattern.



I am always eager to discuss my research or consider a collaboration - please feel free to contact me.