Lightning-rainfall relationship in El Niño and La Niña events during the Indian summer monsoon over central India

Abstract

The Indian summer monsoon rainfall (June-September) on a regional scale is critically important for agriculture and water management in India. The current study presents the lightning-rainfall relationship during El Niño (drought) and La Niña (flood) events in the Indian summer monsoon over central India. The results show that the flash count, Bowen ratio, surface maximum temperature, total heat flux, aerosol optical depth (AOD), sea surface temperature (SST), and Niño 3.4 index are increased by 36, 62, 19, 12, 46, 4.7%, and 0.3 ºC (warmer), whereas the rainfall is decreased by 15% during El Niño years with respect to normal years. The flash count, Bowen ratio, surface maximum temperature, and AOD are found to decrease by 15, 11, 3.5, and 11.1% during La Nina years, whereas the rainfall, total heat flux, SST, and Niño 3.4 index are found to increase by 2.4, 1.72, 0.36%, and –0.68 ºC (cooler) during La Niña years with respect to normal years. The increase in the flash count and the reduction in rainfall are associated with the warm phase of El Niño-Southern Oscillation (ENSO) (El Niño), which causes the weakening of the Indian summer monsoon. The decrease in flash count and increase in rainfall is due to the cold phase of ENSO (La Niña) and is associated with the strengthening of the Indian monsoon season. The increase in the number of break days and low-pressure systems also plays an important role in El Niño and La Niña years, respectively, over central India during the Indian summer monsoon.