North East/Winter Monsoon over South Asia

North East Monsoon (NEM) or winter Monsoon is a critical rainy season for water scare arid and eastern coastal regions over the tropical southern peninsular India and adjoining south Asia. The rainfall received in the season is vital in water management and agricultural production. The NEM seasonal weather has high socioeconomic importance over the region. This study analyzed long-term changes in NEM monsoon characteristics using India Meteorological Department observations and ERA5 reanalysis. The NEM characteristics are least studied compared to the South Asian summer monsoon in June to September. Compared to the south Asian summer monsoon season, the NEM rainfall spells are much more scattered, convective and uncertain. Strong Low-level easterly winds and the presence of tropical lows, depressions or cyclones chiefly contribute to seasonal rainfall. Heavy rainfall spells in the season cause addon hazards like floods. Our analysis of long-period rainfall and reanalysis parameters (mean sea level pressure in Siberia, Mean Sea level pressure at the adjacent northern India oceanic region, latent heat flux and easterly wind) show that there is an increase in rainfall days in NEM period. The widening of the season was caused by the extension of the season in enhanced January month rainfall activity in the recent two decades. The trends are significant (0.01 level), and it is coherent with the mean sea level pressure and surface latent heat flux changes over the adjacent northern Indian Ocean.