Global statistics of lightning in anvil and stratiform regions over the tropics and subtropics observed by the Tropical Rainfall Measuring Mission

Abstract

[1] The statistics of lighting in the anvil and stratiform regions of convective systems are summarized from Tropical Rainfall Measuring Mission (TRMM) satellite observations from 1998 to 2009. The locations of lightning flashes in convective systems are determined by combining three-dimensional precipitation radar (PR) observations with lightning flash center locations from lightning imaging sensor observations. The geographical distributions of flashes in the anvil and stratiform regions of thunderstorms over the tropics and subtropics are presented. Flashes in stratiform regions are found to account for 5.6% of all lightning flashes observed within the TRMM PR swath, while flashes in nonraining anvil regions made up another 5.5% of the sample. Diurnally, flashes in anvil regions peak earlier than flashes in stratiform regions (15:30 LT as opposed to 17:30 LT). Seasonal and regional variations of these flashes are discussed. Features in PR observations that likely contribute to charge separation are identified as contiguous areas with 6 km echoes exceeding 30 dbZ. Lightning flashes are then assigned to one of these features by the nearest neighbor method. Convective properties of features linked with lightning in stratiform and nonraining anvil regions are then analyzed. We find that features associated with lightning flashes in anvil regions are relatively weak and occur in small systems composed of a single convective region, while flashes in the stratiform regions are also relatively weak but more likely occur in multicell systems. About 15% of features with lightning are associated with at least one stratiform or anvil flash.