Unraveling the characteristics of precipitation microphysics in summer and winter monsoon over Mumbai and Chennai – t the two urban-coastal cities of Indian sub-continent

Abstract

The characteristic features of inter-seasonal variability of precipitation microphysics for the year 2019 over Mumbai and Chennai – the two urban-coastal cities of Indian sub-continent have been studied in this paper. The importance of choosing the regions lies in the fact that these two cities are well-known for the occurrences of severe rainfall events due to the effect of south-west and north-east monsoon during the summer and winter season of Indian sub-continent respectively. It has been observed that raindrops of diameter 2-–4 mm dominate the summer rainfall over Chennai with respect to winter rainfall. Correspondingly, while comparing the two cities together, the impact of the south-west and north-east monsoon in conjunction with the interplay of the continental and maritime effect on the microphysics of precipitation over these cities is strongly visible in the analysis. The study reveals that the rainfall evolving from the continental clouds along with contrasting surface temperature produces distinct diurnal variation for the summer (winter) rainfall over Chennai (Mumbai) while such variations are not visible for the maritime clouds. It has been observed that the drops of larger diameter along with higher radar reflectivity dominated the summer rainfall of Chennai with respect to Mumbai. While for the winter rainfall, such distinct variations are visible only for higher rainfall regimes from 16 mm/h and above where the domination of larger drops is visible for the Mumbai rainfall. Thus the difference in surface temperature which in turn escalates the convective environment in the atmosphere can be termed as one of the important factors responsible for this inter-seasonal variability of precipitation microphysics. © 2020 Elsevier B.V.