Vertical structure of the lower atmosphere over the Arabian Sea and West Coast Station during weak phase of the Indian summer monsoon

Abstract

<smarttagtype namespaceuri="urn:schemas-microsoft-com:office:smarttags" name="place" downloadurl="http://www.5iantlavalamp.com/"> The height of the day time mixed layer, vertical structure of the atmospheric boundary layer (ABL) and its variation over the Arabian Sea (hereafter Sea) and the West Coast Station (Goa: 15^o21' N, 73^o51' E) during the weak phase of south-west monsoon (20-24 July 2002) have been calculated using Radiosonde, the surface meteorological data collected at 12 m above mean sea level onboard ORV Sagarkanya and at Goa during ARMEX-I. It is observed that the depth of mixed layer over Goa and offshore was about 1 km during the period, while the first 200 m was showing super adiabatic lapse rate over Goa but not over the Sea. The marine atmospheric boundary layer is found to be well-mixed with its height, progressively increasing from 750 m to 1000 m during 21-24 July 2002. The vertical profiles of virtual potential temperature show an inversion above 1 km, which was very steep over both the Sea and Goa. The relative humidity (RH) in the mixed layer (0-1 km AGL) was varying from 70 to 100% over the sea, whereas over Goa it was from 70 to 90 % during 20-24 July 2002. Above 2-3 km, RH decreases from 70% to 30% over the Arabian Sea and Goa on 24 July, indicating the presence of subsiding warm and relatively dry layer. </smarttagtype>