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Lightning activity and its connection with weather-related parameters over Sri Lanka

Umakanth Nandivada, Chandrasekhar Annur Vivekananda, Smitha Akkarapakam Sujala Swapna, Vasantha Bhavani, Rao Karuturi Srinivasa, Koutavarapu Ravindranadh, Rao Myla Chimpiri

Acta Geophysica

2025

Vol. 73, no. 1

995--1015

This study analyzed lightning activity along Sri Lanka using lightning imaging sensor for a 17-year period (1998-2014). To understand the influence of various parameters on the lightning activity, we investigated various meteorological parameters such as convective precipitation, relative humidity, cloud top temperature, cloud base height, convective available potential energy, total precipitable water, rain dynamic index, humidity index, convection inhibition, lifted index, K-index, total totals index, show alter index, vertical velocity and dew point depression (Dpd). North-western, Western, Southern and Sabaragamuwa regions of Sri Lanka showed high lightning activity. The analysis revealed different seasonal variations in lightning activity. The pre-monsoon season showed the maximum frequency, while winter witnessed the least. In addition, wind patterns embedded with moisture seem to influence regional variations over Srilanka. The westerly winds might influence lightning activity over Srilanka. We investigated the variations of different meteorological parameters for 40 lightning and no lightning days during the study period. During lightning days, the VV values show negative values with strong lightning and convection potential and strong atmospheric updrafts. Higher atmospheric levels have been found to contain dry air, and lower atmospheric levels have been found to contain moist air on lightning days. Extremely unstable atmospheric conditions that favour intense lightning activity were indicated by LI values less than -4.

Increasing pre-monsoon rain days over four stations of Kerala, India

Umakanth Nandivada, Kalyan S. S. S., Satyanarayana Gubbala China, Gogineni Rajesh, Nagarjuna Ayachithula, Naveen Ramisetti, Rao Kokkerapati Ramachandra, Rao Myla Chimpiri

Acta Geophysica

2022

Vol. 70, no 2

963--978

The climate of India varies greatly by region, as seen by wind patterns, temperature and rainfall, seasonal rhythms and the degree of wetness or dryness. During the several seasons, the weather conditions change. Changes in meteorological factors (temperature, pressure, wind direction and velocity, humidity and precipitation, etc.) cause these changes. The pre-monsoon season (PRMS) comprises of March, April and May months. The precipitation patterns observed in PRMS are crucial because it affects a variety of crop-related operations across the country. The lifting index (LI), K index (KI), total totals index (TTI), humidity index (HI), improved k index, improved total totals index, total precipitable water (TPW) and convective available potential energy (CAPE) are studied at four locations in Kerala during PRMS. These variables were examined on rain day (RD)’s and no rain day (NRD)’s. The four stations we chose for our investigation were Thiruvananthapuram, Kochi, Alappuzha and Kannur. The GPM IMERG (Integrated Multi-satellite Retrievals for Global Precipitation Measurement) daily rainfall datasets have been utilized for this analysis. Fifth-generation ECMWF atmospheric reanalysis (ERA5) daily data for the PRMS of 2021 were used to measure all rainfall-related variables. During PRMS, all metrics clearly distinguished the RD and NRD. The rise in relative humidity and observations of dew point depression indicates that there is enough moisture for convective rain. In May, there were more negative VV values than in April.