Lightning and its association with low pressure systems over the Indian seas

The main objective of this work is to study the lightning activity associated with low pressure systems (LPS) over Indian seas : Arabian Sea (AS) and Bay of Bengal (BoB) by using Lightning Imaging Sensor (LIS) gridded (1ox1o) data for a 10 year period (1998-2007). The spatial variation of lightning activity is found to be maximum at 7o-9oN and 65-73oE over AS, whereas over BoB the activity is maximum at 16o-20oN and 87o-89oE. The study revealed that the monthly mean variation of lightning and Sea Surface Temperature (SST) a maximum occurrence in the month of (May and October). The amplitude of first maximum (May) is higher than second maximum (October). The behavior of lightning and sea surface temperature (SST) for the months (March-September) during drought, deficient and normal monsoon years (2002, 2003 and 2004) is also examined. The analyses shows that peaks SST and lightning occurred in the month of April for 2002 and 2004 (drought and deficient monsoon years) over AS and for 2003 (normal monsoon year) the lightning and SST peak occurred in the month of May over AS and BoB. The authors have also made an effort to examine first time the influence of low pressure system (LPS) and interactions with change in SSTs over the Indian seas. The monthly variation of LPS over Indian seas shows that the performance of the monsoon on a seasonal and monthly basis respectively depends on the total number of lows and depressions forming in the monsoon trough and the number of days with the existence of LPS. The LPS tracks reach up to northwest India during normal years whereas they are confined to central India during drought years.