Tropical orographic rainfall regimes according to the Tropical Rainfall Measuring Mission

This study seeks to (1) analyze the variables and parameters that influence precipitation mode and structure near complex terrain and (2) analyze the vertical and horizontal structure of precipitation systems in regions of complex terrain. For this study, we will analyze 12 years (1998-2009) of TRMM precipitation radar (PR) data over the tropical Andes, Hawaii, Himalayas, Sierra Madre Occidental, and Western Ghats to examine the structure of precipitation systems and determine which atmospheric variables and parameters interact to influence precipitation structure and variability. We will use NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA) data to evaluate how atmospheric variables including specific humidity, wind direction, and wind speed and atmospheric parameters such as moist Froude number (Fm) and CAPE impact the formation and propagation of precipitation in the regions of interest. TRMM combined 3B42 3-hourly rainfall will be used to determine precipitation mode and amount, while TRMM PR 2A25 raw data will be used to determine the vertical and horizontal structure and propagation of the precipitation systems. The TRMM combined and PR data will be analyzed for each region of complex terrain to examine how changes in the controlling atmospheric conditions impact the mode, propagation, and structure of the precipitation systems. Available ground validation networks will also be used to verify the TRMM rainfall variability and patterns.