Environmental Controls on the Vertical Structure of Tropical Orographic Precipitation and Implications for Passive Microwave Retrievals

This study seeks to investigate the vertical structure of tropical orographic precipitation using dynamic and thermodynamic variables and parameters that are known to influence precipitation mode and structure in regions of complex terrain. Prior work has shown that the spatial distribution and intensity of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) observed orographic precipitation has strong thermodynamic and dynamic controls when stratified by selected environmental parameters from the NASA Modern Era Retrospective-Analysis for Research and Applications (MERRA). Since the retrieval of precipitation from passive microwave sensors depends on the vertical structure of convection, we also investigate the role of the vertical structure of orographic precipitation on biases in orographic precipitation retrievals as a function of regime.

In this study, we use the fourteen years (1998-2011) of Tropical Rainfall Measuring Mission (TRMM) precipitation radar (PR) and TRMM microwave imager (TMI) data to investigate the vertical structure and modes of orographic precipitation in these regions while also using this analysis framework to quantify errors in precipitation retrievals, both using MERRA thermodynamic and dynamic quantities. We will contrast our findings with the Asian Precipitation – Highly-Resolved Observational Data Integration Towards Evaluation (APHRODITE) rain gauge network in the eastern Himalayas, Japan, and Western Ghats ranges, as well as the Climate Prediction Center (CPC) rain gauge network in the tropical Andes, Hawaii, and Sierra Madre Occidental. Through a better understanding of environmental controls on the structure of tropical orographic precipitation, the combined data sets will be used to develop a statistical tropical orographic precipitation correction for passive microwave sensors based on the defined environmental variables and parameters.