Satellite observation of lightning activities over Sri Lanka

Abstract

Fifteen years of remotely sensed satellite mounted Lightning Imaging Sensor (LIS) data were used to determine the characteristics of lightning activities over Sri Lanka. The LIS is capable of detecting lightning flashes with 69% accuracy during day time and 88% accuracy during night time. In this study, a 5×5 km2 grid was used for the analysis. From 1998 to 2012, there were 16,699 lightning flashes over the land mass covered by Sri Lanka. The data show that the highest occurrence of lighting activities is confined to the highly populated western part of the island while the south eastern and mountain areas have low occurrences. There is a clear spatial polarization of lightning activities during the south-west and north-east monsoon seasons. Lightning activities appear to be increasing by 50 flashes per year.It has a seasonal dependency with the south-west and first inter-monsoon seasons having the higher increase. The estimated maximum cloud toground lightning flash density was 19 flashes yr-1 km-2 observed during the south-west monsoon season.Inter-annual variation of occurrence of lightning flashes shows the expected bimodal distribution with the month of April having the highest occurrence of over 300 flashes.