Land-ocean contrasts in lightning activity over the Indian region.

Land-ocean contrasts in the lightning activity over Indian land and two surrounding oceanic regions viz. Arabian Sea and Bay of Bengal have been studied. Satellite-based lightning flash data for 5-year (1998–2002) period have been used. The study revealed that lightning activity over Bay of Bengal was three times higher than that over Arabian Sea and 9.3 times lower than that over land. The bimodal distribution is seen over Arabian Sea (peaks in April and November), and land (peaks in May and September). A unimodal distribution is observed over Bay of Bengal with peak in May. The maximum activity over Bay of Bengal occurs more at northern latitudes (28–30°N) compared with Arabian Sea (12–14°N). The land–ocean contrast is dominated by monsoon season. Comparison of lightning activity in the El Nino (2002) and La Nina year (1998–2001) shows that the lightning activity is increased by nearly 18% over the land region and it maybe attributed to in the increase in surface air temperature during the warm phase of El Nino, land sea breeze circulations and difference in the continental and the oceanic convection. Copyright © 2009 Royal Meteorological Society