Study on the north-east monsoon onset features using a ground-based microwave radiometer over SHAR

Abstract

Convection has a significant role in maintaining the atmospheric dynamics and thermodynamics; particularly in the tropical regions, it can often lead to the formation of clouds and precipitation, release of latent heat, etc. Microwave radiometers (MWRs) have evolved as a powerful tool for monitoring the genesis and evolution of the convection over a site. Ground-based MWRs are installed at the Satish Dhawan Space Centre SHAR, (SDSC SHAR) Sriharikota (13.72°N; 80.18°E) located over south coastal Andhra Pradesh, the south-east coast of India in 2014. MWR provides high temporal resolution vertical profiles of temperature, vapour density and liquid column measurements. The mean profiles of temperature and vapour density of upper-air ascents of GPS radiosonde and microwave radiometer (MWR) are compared for the same location. After the middle of October, the rainfall pattern over south peninsular India and in particular Tamil Nadu and south coastal Andhra Pradesh is due to the arrival of the north-easterly/easterly winds. The aim of the present study is to use MWR products for the north-east monsoon (NEM) onset study. In addition to the European Centre for Medium-Range Weather Forecasts (ECMWF) and operational WRF models, reanalysis data products were also used for the study. The association between the temporal evaluation of thermodynamic profiles and NEM onset has been tested for 3 years. The present results suggest that during the period of NEM onset, 3–5 days early signatures can be observed by MWR.