Thermodynamic structure of the boundary layer in relation to a monsoon depression over the Bay of Bengal — A case study

Aerological observations carried out on board ORV Sagarkanya at a stationary location (20° N, 89° E) over the Head Bay of Bengal during August 18–21, 1990 were analysed to study the thermodynamic structure of the marine boundary layer in relation to a monsoon depression which formedin situ with its centre at 20° N, 88° E. The q(mixing ratio) reversal observed at 850 hPa prior to formation of the low pressure area shifted to a higher level (h<700 hPa) with the formtion of the low. Positive buoyancy below 850 hPa prior to the formation of the low indicated conditions favourable for deep convection. When the low pressure area intensified into a depression, negative buoyancy was observed at lower levels.