Seasonal variation of DSD parameters during stratiform and transitional precipitation over a coastal station Thumba (8.5°N, 76.9°E)

Abstract

Using the observations of both ground based disdrometer and Micro Rain Radar, Drop size distribution (DSD) parameters were derived using gamma function over coastal station Thumba. Stratiform rain and transition rain regime has been considered to study the vertical variability of DSD parameters for different monsoon seasons during 2006- 2008. The analysis clearly reveals a significant variation in DSD parameters for different seasons. Contour Frequency by Altitude Diagram (CFAD) of DSD parameters is carried out to examine salient microphysical characteristics of DSD during these two rain regimes. Results show that the observed variability of gamma parameters and median volume diameter is attributed to microphysical processes like evaporation, break-up and collision-coalescence. The significance of the present results demonstrates the capability of Ka band radar in understanding the microphysics of rain during light to moderate rain regimes