Detail Abstract

Climatological intraseasonal variation in aerosols and their impact on extreme rainfall over India

Abstract

The aerosol distribution are interrelated with the intraseasonal variations in Asian summer monsoon winds. Due to the intraseasonal variations in winds, the spatial distribution of aerosol over India changes. These climatological features are analyzed using the MODIS satellite observation and CAMS reanalysis datasets. Eight phases of MISO (Monsoon Intraseasonal Oscillations) are computed using the MISO index. The differences in distribution of aerosols in eight MISO phases influence the incoming solar radiation, cloud properties, and convection processes. These features are analyzed over the Central region of India which is known as the monsoon core region of India. Reduction in incoming solar radiation, influences the convection processes and suppresses the strength of convection and hence reduces the occurrence of extreme rainfall events (EREs) over Central India.</br> To understand the impact of MISO-related variation of aerosols on EREs, we analyzed it in the high and low aerosol scenarios during the phases of MISO. We found that in the MISO phases of low (high) aerosols,  frequency of extreme rainfall is found more (less). However, the MISO-related variation of mean rainfall was different. It was found to have a peak during the transition phases corresponding to low and high aerosols. Interestingly, the fraction of clouds was found to be more (less) in the high (less) aerosol phases. Thus, we analyzed the combined direct and indirect effects of aerosols and their influence on the extreme rainfall events over Central India.