Diurnal variations in lightning over India and three lightning hotspots: A climatological study

Abstract

Advancements have been made in the field of lightning research. A study on lightning frequency in India, a tropical hotspot, has not been conducted despite the existence of a global climatology on mean flash rate lightning. Lightning climatology in India is determined using high-resolution datasets from MicroLab-1 and Tropical Rainfall Measuring Mission (TRMM) satellites and Lightning Imaging Sensor (LIS) diurnal datasets spanning from 1996 to 2013. The study analyzed the difference in density of lightning flashes during two time periods, 1996–2001 and 2008–2013, on a daily, monthly, and seasonal level. Three regions with high lightning activity have been selected: East Khasi Hills in the northeast with 101.25 flashes/Km2/yr, Rajouri in Jammu & Kashmir with 121.40 flashes/Km2/yr, and Kottayam with 92.94 flashes/Km2/yr. The study focuses on the rainfall, convective available potential energy (CAPE), and lightning density. Due to localized climatological factors, lightning events vary in diurnal and seasonal patterns across the three hotspots.Lightning strikes are predominantly distributed in certain regions of India, including Jammu, Kashmir, the foothills of the Himalayan belt, and the North-Eastern region, encompassing Bangladesh, Bihar, Jharkhand, and Orissa. The frequency of lightning strikes ranges from 0.2 to 0.45 flashes/Km2/day. Lightning activity experienced a slight rise between 2008 and 2013. There was a rise in lightning activity (0.04 flashes/Km2/day) in India and its three hotspots in 2010. The study aims to investigate the daily changes in lightning activity. A significant portion of daily lightning activity occurs at approximately 1000 UTC and generally decreases in the afternoon across all seasons. The study examines the seasonal variation in lightning activity across India, specifically during pre-monsoon, monsoon, post-monsoon, and winter. The results are significant for developing lightning climatology in the region. Lightning density in India experiences a slight increase during both pre-monsoon and monsoon seasons, with a noticeable variation observed across India and three hotspot locations.