Regional Variation in Precipitation characteristics observed by space-borne Precipitation Radar

Dual-frequency precipitation radar (DPR) placed on the Global Precipitation Measurement (GPM) satellite provides a three-dimensional distribution of precipitation between 65⁰N- 65⁰S. The availability of precipitation parameters at the spatial resolution of 0.1⁰*0.1⁰ and temporal resolution of 30 minutes can be used to investigate the microphysical process responsible for the precipitation. We analyzed the GPM-DPR level 2 V07 observed data collected over the Southern region of India and the surrounding Oceanic region to understand the precipitation characteristics in the pre-monsoon and monsoon seasons. India Meteorological Department (IMD) gridded rainfall data at the resolution 0.25⁰ is used to validate GPM-DPR data over the landmass region. There is significant variation in the temporal and spatial distribution of reflectivity (Z), rain rate (R), and DSD parameters such as mass-weighted mean diameter (D_m) and normalized intercept parameter (N_w). In the monsoon season, higher precipitation frequency provides considerable accumulated precipitation throughout India. However, the frequency of intense rainfall is higher in the pre-monsoon season than in the monsoon season, as most of rain events occur over the Ocean instead of land. The mean of R, Z, and D_m is small, and a large N_w value is observed in the monsoon season, as stratiform clouds (more than 68%) contribution in monsoon precipitation is more than convective clouds. The distribution of average D_m, Z, and R in pre-monsoon indicates the presence of bigger rain droplets, possibly due to the enhancement in the collision-coalescence process and slow-down of the break-up process. The share of convective clouds in overall precipitation on the land surface increased in the pre-monsoon season. The fluctuation in D_m not only occurs with topography, season, and R, but also with the concentration of heavy ice precipitation particles above the bright band and microphysical process. Simultaneously, in both pre-monsoon and monsoon seasons, a modest relationship was detected between the incidence of heavy precipitation and maximum echo top reflectivity.