Characterization of Different Rainfall Types from Surface Observations Over a Tropical Location

Abstract

This study characterizes different rainfall types using surface-based instruments (i.e. micro rain radar and laser precipitation monitor) installed at the Indian Institute of Technology Bhubaneswar Jatani, Odisha, India. A total of twelve rainfall cases including four from each season, i.e. pre-monsoon, monsoon and post-monsoon, are considered. The segregation of rainfall is carried out using radar reflectivity and rainfall intensity. In general, initial rainfall is dominantly convective and followed by a stratiform type. Two distinct maxima of radar reflectivity are noted at 3 and 5 km, suggesting the presence of high liquid water content and a melting band. The presence of liquid water content suggests occurrence of a warm rain process with shallow, intense convective cores. Results indicate a higher drop number density below 2 km with smaller size drops for convective rainfall and vice versa for the stratiform rainfall. Furthermore, Z–R relationships are computed for all the cases using a linear regression method, and the results suggest that the stratiform rainfall shows a higher slope parameter and lower intercept parameter as compared to convective rainfall. The distribution of drop number density shows a mono-modal and bimodal pattern for convective and stratiform rainfall, respectively.