Tuesday, 22 January 2008
Using TRMM to resolve the ensemble of global tropical thunderstorms
Exhibit Hall B (Ernest N. Morial Convention Center)
Since its inception in 1997, the Tropical Rainfall Measurement Mission (TRMM) has monitored rainfall and lightning over the tropics on a daily basis. TRMM carries several advanced instruments that perform these observations, including the Lightning Imaging Sensor (LIS), Precipitation Radar (PR) and the TRMM Microwave Imager (TMI). Using the TRMM LIS and PR datasets (and later TMI data), an algorithm has been developed to locate and extract individual thunderstorm “cell” descriptive characteristics (storm structure, lightning etc.) stored within the University of Utah mesoscale features database. Because the production (but not necessarily propagation) of lightning in a thunderstorm occurs predominantly over convective scales (O[10x10 km]), the resultant high resolution cell-scale analysis should enable some refinement of previous global comparisons of lightning and storm structure by better resolving the sub-mesoscale entities responsible for storm electrification and lightning. Because cell identification is accomplished using data from within the mesoscale features database, the relationship between cell structure and lightning occurrence can be further explored with regard to the structure of the parent mesoscale convective system and synoptic scale environment. Finally, since the TRMM dataset now spans a decade, it will be possible to document the decadal tendency of lightning and non-lightning producing convective cells (i.e., individual “thunderstorms”) over the global tropics. This study will present a discussion of the science and methodology used, and a sample of the cell-scale lightning and storm structure analysis.