Local summer monsoon precipitation patterns in the Western Ghats

The Southeast Asian Summer Monsoon brings heavy and highly variable rains June-September to the Indian subcontinent, with some of the heaviest rainfall occurring over the Western Ghats and offshore, over the eastern Arabian Sea. Larger-scale features such as the Somali Jet, synoptic disturbances, and the presence of the Western Ghats themselves contribute to the production of precipitation in this region, but the nature of the processes that regulate smaller-scale patterns of precipitation are still unclear. We hypothesize that the unique and varied 3D topography of the Western Ghats and land surface-atmosphere interactions impact seasonally salient precipitation patterns at smaller scales. Due to paucity of meteorological and land surface data, we employ the Advanced Weather Research and Forecasting model and the Land Information System to perform suites of 3D, high-resolution simulations over the 2008, 2009, and 2010 monsoon seasons. By comparing the results of our simulations against satellite estimates of precipitation from the Tropical Rainfall Measuring Mission and our rain gauge network installed along two transects in Karnataka, India, we identify previously undocumented local precipitation patterns and determine the dominant processes that lead to the observed patterns. Within this analysis, we also assess the presence and strength of a diurnal land-sea breeze cycle during 1) active monsoon periods, and 2) breaks. We conclude with a summary of how thermodynamic and stability parameters such as static stability (Nm^2), Froude Number (Fr), Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), level of free convection (LFC), and cross-barrier wind (U) can be used to diagnose observed precipitation patterns.