Sodar observed winds in the convective boundary layer at Kharagpur, India, during monsoon 1990

Abstract

Sodar has been installed at Kharagpur (22.2° N, 87.3^oE) as a part of the Monsoon Trough Boundary Layer Experiment (MONTBLEX-90) and data were collected during the monsoon period. The monthly-mean wind field variation in the convective boundary layer (CBL) at Kharagpur during the S-W monsoon of 1990 has been studied. Monthly-mean horizontal winds were found to be westerly/north-westerly in the convective boundary layer above - 600 m in all the monsoon months. In August, mean winds near the surface have become easterly in response to the monsoon depressions formed in the north Bay of Bengal during 15-31 Aug, 1990. Two case studies of depression are studied in terms of winds and thermal structure in the convective boundary layer at Kharagpur. The variation of CBL height over Kharagpur during the onset, active and low/depression phases of the monsoon 1990 is also presented.