Spatial and Temporal Variability of Lightning Activity in Sri Lanka

Sri Lanka is one of the major lightning prone countries in the South Asia and Lightning kills in Sri Lanka about 50 people each year. The spatial and temporal variability of lightning activity in Sri Lanka from 2015 to 2018 has been studied using GLD360 lightning location data in 2 km × 2 km grid. Vaisala GLD360 lightning location data was provided under the collaborative project “Severe Storm Warning Services for Sri Lanka (SSWSS)” with the Finnish Meteorological Institute and Vaisala Inc. These data have been examined for depicting the annual, seasonal, and spatial distribution of the lightning activity. The study indicates that the annual mean lightning rate for the period from 2015 to 2018 is maximum in an area along the western foothills of central hills and decreases at higher elevation of central hills; this is linked with the convective activity due to solar heating of land, large-scale circulations, local winds such as sea breeze, and orography. Highest annual average amount of lightning are evident in Kegalle and Gampaha districts. Seasonally, a bi-model pattern of lightning occurrence is visible with maxima during the first intermonsoon season (FIM, March to April) and the second highest in the second intermonsoon season (SIM, October to November); the lowest amount of lightning are observed in the northeast monsoon season. Monthly variability shows that the maximum number of lightning is observed in April during the FIM season. The analysis of this study provides useful information of spatial and temporal pattern of lightning activity during the four climatic seasons in Sri Lanka, and the results can be used especially in decision-making and disaster risk management to aid, for example, in the understanding of where to focus safety education to reduce lightning fatalities and injuries