Using TRMM to resolve tropical convection for lightning climatology

Having completed over a decade of observations, the Tropical Rainfall Measurement Mission (TRMM) provides a unique opportunity to examine the recent precipitation climatology of the global tropics. Among its instrumentation, the TRMM satellite carries the Precipitation Radar (PR), the Lightning Imaging Sensor (LIS), and the TRMM Microwave Imager (TMI). Using these datasets, the University of Utah (U. Utah) developed a processing algorithm to mine mesoscale features and associated PR, TMI, and LIS parameters in the course of building a mesoscale “features” database.

Following the U. Utah example in the process of pursuing our own work focused on cell-scale thunderstorm characteristics, we have developed software that further refines the U. Utah mesoscale precipitation features database . This software mines the U. Utah features database to further resolve either isolated or embedded thunderstorm cells using PR reflectivity texture and vertical structure. The software then creates a separate convective scale database of relevant characteristics from the PR, TMI, and LIS data.

Convective scale analysis (O[10 km X 10 km]) of embedded or isolated cells enables the cloud electrification process to be studied more specifically because in reality, thunderstorm electrification is driven primarily by processes occurring on the cell scale (mesoscale stratiform regions excepted). In the spirit of thunderstorm studies at the cell scale, we then compare lightning flash rates in convective cells to other storm parameters, such as the vertical profile of radar reflectivity, minimum brightness temperature, and ice water path. The focus of this study is to refine our understanding and interpretation of lightning in tropical convection as a function of these parameters, and to compare the electrification processes over varying regimes, such as tropical oceans, tropical continental, near mid-latitude continental, and others. This presentation will present a basic overview of the processing and a sample of scientific results focused on cell-scale correlations between relevant radar, radiometer, and LIS-diagnosed parameters from multiple seasons in the deep tropics.