Dual-Polarization C-Band Radar–Inferred Rain Microphysics in the Indian Core Monsoon Zone

Abstract Radar polarimetric parameters offer remarkable insights into the microphysical processes of precipitating systems. The Indian Institute of Tropical Meteorology established a C-band polarimetric radar in the Indian core monsoon zone to examine the properties of convective storms. This study uses C-band polarimetric radar to investigate the microphysical structure of a heavy rainfall event observed on 22 August 2022. Radar observations reveal that stratiform rainfall prevailed during the heavy rainfall day. The quasi-vertical profiles of radar polarimetric variables are calculated to characterize the possible microphysical processes governing the heavy rainfall. These analyses are supplemented by microwave radiometer and reanalysis data. The radar polarimetry and reanalysis data suggest the signatures of planar crystal/dendritic growth near −15°C. The heavy rainfall event is associated with sagging of the melting layer. The polarimetric radar variables and microwave radiometer retrievals reveal the probable association of riming and secondary ice production with the melting-layer sagging. These insights are a preliminary step toward a better understanding the complex microphysical processes associated with monsoon rains over India. Significance Statement Due to the lack of adequate observational facilities, the knowledge of precipitation processes is limited in the Indian subcontinent. The dual-polarization radar offers polarization measurements that can be used to understand the type of precipitation medium (liquid, ice, etc.), as well as the size, shape, and orientation of precipitation particles. In the context of an increased frequency of heavy rainfall, the present study used the C-band dual-polarization radar measurements to infer the rain microphysical processes in mixed-phase and liquid-phase regions over central India in the core monsoon zone. This work sheds light on the major microphysical processes during a heavy rainfall event, which can be helpful for model intercomparison and validation.