Lightning Distribution during Active and Break Monsoon Periods over South Asia

Abstract

The Indian summer monsoon rainfall and its annual variability is generally determined by the performance of monsoon in the monsoon zone of India. Variability of monsoon rainfall, especially in the monsoon zone of India strongly depends on the intensity and duration of the active and break monsoon periods. Several factors such as rainfall, convection, convective available potential energy (CAPE), surface temperature, relative humidity, topography, etc. considerably differ during the active and break monsoon periods. These factors also affect the lightning activity in a particular region. Since the performance of monsoon crucially depends on the intensity and the duration of the active and break periods, it is important that the link between the lightning activity and these environmental factors is examined over the monsoon zone of India. This thesis tries to examine these related links over South Asia with the help of satellite data for lightning activity. We first identify active and break spells during 1995--2012 based on the precipitation in the monsoon core zone. Then, we examine lightning distribution in this region during active and break spells during the monsoon for this eighteen year period. The relation between the position of the monsoon trough and the zone of maximum lightning flash rate is then examined. Correlation is observed between lightning distribution and the monsoon trough position during these active and break spells. Further work is to be carried out to understand this observed correlation, by studying the link of the above mentioned environmental factors with lightning within the regimes of active and break spells.