Topography, relief, and TRMM-derived rainfall variations along the Himalaya

Along the southern Himalayan topographic front, the Indian summer monsoon modulates erosive processes and rates. To investigate the influence of topography and relief on rainfall generation and resultant erosion, we processed satellite rainfall amounts for the last 8 years (1998-2005) from the Tropical Rainfall Measurement Mission (TRMM). Based upon a spatial resolution of similar to 5x5 km for the Himalaya, we identify (1) the spatial distribution of rainfall and (2) the large-scale relationships between topography, relief, and rainfall locations. Our results show two distinct rainfall maxima along strike in the Himalaya. The first, outer rainfall peak occurs along the southern margin of the Lesser Himalaya within a narrow band of mean elevation (0.9 +/- 0.4 km) and mean relief (1.2 +/- 0.2 km). The second, discontinuous, inner band typically occurs along the southern flank of the Greater Himalaya (elevation and relief: both 2.1 +/- 0.3 km).