Reflectivity-rain rate relationship for the orographic rainfall over the Western Ghats

Joss-Waldvogel Disdrometer (JWD) measurement between 2015 and 2019 at the High-Altitude Cloud Physics Laboratory, Mahabaleshwar, is performed for determining the seasonal characteristics of the drop size distributions and the power law (Z= aRb) relationship between the reflectivity (Z) and rain rate (R). It is observed that the number concentrations of rain droplets of various diameters fluctuate with the cloud type, rain rate, and season. In the monsoon, smaller (< 1 mm in diameter) rain droplets concentration is maximum, while the middle (1-3 mm) and bigger (>3 mm) droplets concentration is high during the pre-monsoon season. The number concentration of bigger (smaller) rain droplets is increasing (decreasing) with the intensity of the rain. It is also observed that convective precipitation contains a higher concentration of bigger rain droplets than stratiform precipitation. The probability density distribution of the rain-integral parameters indicates that the contribution of different microphysical processes like collision-coalescence, break-up, size sorting and evaporation processes is varying with the cloud type (convective and stratiform) and season. Due to these variations in DSD characteristics, the exponential relationship between Z and R is unique for the convective and stratiform precipitation during the monsoon and pre-monsoon seasons. The derived Z-R relationship's numerical coefficient is larger for the stratiform precipitation than the convective precipitation in each season, aggregable to the previous study for the monsoon season. The distinct Z-R relationship for convective and stratiform precipitation is mainly due to the difference in the contribution of the various microphysical processes in rainy cloud formation.
The 28th IUGG General Assembly (IUGG2023) (Berlin 2023)