Lightning activity over Telangana and Andhra Pradesh states situated in the east coast of India
Authors: Penki Ramesh Kumar , S.S.V.S.V.S Ramekrishna , Gautam Alok Sagar , Narita Tomomi 
Published: May 2022

Abstract
Lightning activity over Telangana (latitude: 17oN-19oN and longitude: 78oE-820E), and the 13 districts of Andhra Pradesh are studied using the lightning imaging sensor (LIS) aboard Tropical Rainfall Measuring Mission (TRMM) satellite data during the period 1998–2013. The 13 districts of Andhra Pradesh are divided into two regions in which the 4 districts Anantapur, Chittoor, Kadapa, and Kurnool are referred to as Rayalaseema and the remaining 9 districts (East Godavari, West Godavari, Guntur, Krishna, Nellore, Prakasam, Srikakulam, Visakhapatnam, and Vizianagaram) are referred to as coastal Andhra Pradesh. It is observed that flash rate density and flash count over the study regions (Telangana, Rayalaseema and coastal Andhra Pradesh) exhibit semi-annual variation with primary maximum (during May) in the pre-monsoon season and secondary maximum (during September) in the post monsoon season. Similarly, lightning flash days also exhibits semi-annual variation in the study regions. The primary maximum of flash days in Telanagana is observed during the month of June and secondary maximum is observed during the month of September. The primary maximum of lightning flash days in Rayalaseema and in the coastal Andhra Pradesh districts is observed during May–June and secondary maximum is observed during the month of September. In Telangana and Rayalaseema (except Chittoor district) regions the flash count is highly correlated with surface temperature (0.76 < Correlation Coefficient (CC) < 0.89) and convective available potential energy (CAPE) (0.85 < CC < 0.96). The correlation of flash count with AOD and convective precipitation is very poor over these regions. In Chittoor district flash count is highly correlated (CC = 0.74) with AOD. Similarly, in the districts of coastal Andhra Pradesh (except Guntur, Krishna and Nellore) flash count is highly correlated (0.70 < CC < 0.89) with surface temperature and CAPE (0.85 < CC < 0.95). The correlation of lightning activity with AOD and convective precipitation is very poor over these regions. In Guntur, Krishna and Nellore districts significant correlation (0.72 < CC < 0.81) exists between lightning activity and convective precipitation. The correlation of flash count with meteorological parameters (surface temperature and CAPE) shows that the lightning over Telangana, Rayalaseema excluding Chittoor district and in coastal Andhra Pradesh except Guntur, Krishna, and Nellore districts during pre–monsoon season is mainly due to buoyancy force developed because of the heating of land during daytime. The lightning flash Radiance values over Telangana and Rayalaseema regions are maximum during monsoon season, whereas in coastal Andhra Pradesh flash radiance is maximum during pre-monsoon season. Lightning flash radiance which characterises the strength of the lightning is associated with the structure of the cloud. Annual mean flash count (87.645) over Vishakhapatnam district and flash rate density (0.058 fl.km− 2.day− 1) over Srikakulam district is maximum compared to all other regions. Inter–annual variation of lightning flash count in the study regions shows increasing trend and over Srikakulam district the lightning activity is increasing significantly. This study helps in understanding the spatio–temporal variation and the intensity of lightning activity over Telanagana and Andhra Pradesh, which is first of its kind, over these regions.