The deluge of peninsular India during Northeast Monsoon 2015: Observational aspects of thermodynamical, dynamical and microphysical features

Abstract

During the period 1^st November 2015 to 4^th December 2015, Southern India especially the city of Chennai was battered by heavy rainfall owing to the passage of a Deep Depression during 8-11 November 2015 and low-pressure areas during 13-18 November 2015, 19-24 Nov. 2015 and 29 November 2015 - 4 December 2015. The deluge due to heavy rainfall associated with these systems resulted in enormous loss of life and property. A wave perturbation in deep zonal flow moved from east to west in November 2015. The observational, synoptic, dynamical and microphysical aspects of these systems have been analysed using in-situ surface observations, satellite observations and reanalysed datasets. 

The results show the existence of a dominant trough in the easterlies off the southeast coast of peninsular India at 850 hPa and anomalous anticyclonic circulation over central parts of the country at 500 hPa extending up to the upper troposphere were conducive to the northward movement of these low-pressure systems and copious rainfall over NMR. The surface observational features of the deluge were explored using the Automatic Weather Stations (AWS), High Wind Speed Recording (HWSR) systems, Tropical Rainfall Measuring Mission (TRMM) and Global Precipitation Measurement (GPM) satellites. The microphysical aspects of these low-pressure systems are also analysed using TRMM and ERA-Interim datasets.