Seasonal and regional variation in drop size distributions for different types of rain over northeastern and eastern parts of <scp>India</scp>

Abstract Seasonal and regional variations of Drop Size Distributions (DSDs) of rain are studied at Kohima (25.67° N, 94.08° E) in northeastern India and Rampurhat (24.17° N, 87.78° E) in eastern India, using six years (2017–2022) of data from the OTT Parsivel 2 disdrometer. The DSDs are quantified with gamma distributions and analyzed based on parameters such as slope ( Λ , mm −1 ), shape ( μ ), normalized intercept parameter ( N w , mm −1 ·m −3 ), mass‐weighted mean diameter ( D m , mm) and radar reflectivity factor ( Z , dBZ). Seasonally, larger raindrops prevail during the pre‐monsoon and smaller ones during the monsoon at both stations. Regionally Rampurhat exhibits larger drops compared to Kohima. In both seasons and stations, larger raindrops are found for convective rain than stratiform rain. The observed seasonal and regional variations of surface D m align with Global Precipitation Measurement (GPM) onboard Dual‐frequency Precipitation Radar (DPR) observations. Distinct clusters of D m – log 10 N w suggest maritime characteristics at Kohima and continental characteristics at Rampurhat. Power law relationships are found for N w –R , D m –R and Z–R . Exponent values of Z–R relationships indicate that microphysical processes are mainly driven by both breakup and collision–coalescence (number and size‐controlled) processes. Extremely large‐size raindrops (∼8 mm) and intense rainfall ( R &gt; 150 mm·hr −1 ) are noted during convective rain at Rampurhat.