Convectively-coupled High-frequency Atmospheric waves triggered Kerala floods in 2018 and 2019

Abstract Floods have repeatedly battered the South Indian state, Kerala, as a result of the unprecedented heavy rainfall during Boreal Summers, in recent years. The state witnessed large departures from normal rainfall in 2018 and 2019. Previous studies have seldom adopted a systematic approach to understand the phenomenon responsible for the recurrent extreme events. Hence, this study, based on spectral methods, identifies a characteristic propagation of high-frequency equatorial waves in the atmosphere, which travelled from near tropical west Pacific to the east coast of Africa. These waves stimulated intense convection and ensured sufficient availability of moisture over the state, and are hence responsible for Kerala Floods.