Variability of critical rain drop diameter and its effect on rain attenuation and radar reflectivity

This paper investigates the variability of raindrop size distribution (DSD) and particularly, the role of specific drop sizes in rain integral parameters at a tropical location. Rain DSDs for the years 2006-2007 at Ahmedabad (23°04' N, 72°38' E) have been measured using a Disdrometer. Variability of DSD is evaluated and its effect on the integral rain parameters like radar reflectivity, rainfall intensity and attenuation are examined. It is observed that drops with diameter around 4 mm contribute maximum to the radar reflectivity while drops having diameter 3 mm contribute maximum to the rainfall intensity for the present location. Further, a strong effect due to variability of critical drop diameter is observed on rain rate and rain attenuation but the effect is found to be less pronounced on radar reflectivity.