Climatology of landfalling atmospheric Rivers and associated heavy precipitation over the Indian coastal regions
D. Dhana Laskhmi, A. N. V. Satyanarayana
Abstract
Abstract The Indian coastal regions encountered frequently by extreme weather events such as heavy precipitation events (HPE). In the present study, an assessment has been made to understand the climatological relationship between atmospheric rivers (ARs) and HPEs for Indian coastal regions. For this purpose, India Meteorological Department gridded rainfall dataset, and four different reanalyses datasets for the occurrence of ARs were analysed for different seasons during 1980–2015. The influence of ARs towards the cause of HPEs was stronger over the West coast (WC) compared to the East coast of India (ECI). Over the WC the association between HPE with ARs is ~40% (for rainfall events >124.4·mm·day −1 ) than East coast (EC) by ~28%. The 64.4–124.4·mm·day −1 events are higher over the WC by ~18% compared to ~5% over the EC. While for the events (<64.4·mm·day −1 ), the percentage of occurrence is moreover the WC (~7%) compared to the EC (~2%). The study reveals that ARs is in good correlation with the occurrence of HPE. Using Poisson regression model, investigated the relationship between the AR totals in the summer and Northeast monsoon and the large‐scale climate indices. A sufficiently significant negative (positive) dependency observed between ARs and the Southern Oscillation Index (SOI) (Indian Ocean Dipole [IOD] and Niño 3.4 indices) with a larger rate of AR occurrence associated with lower SOI values and larger frequency of AR occurrence associated with larger IOD and Niño 3.4 values for both the coasts of India.