A study of the atmospheric boundary layer over the Arabian Sea from ISMEX-I973 data

Abstract

The ISMEX-73 data was studied to assess the bulk layer variations in the Arabian Sea along 10⁰N and along the equator. It was found that: (i) Along the equator the friction velocities were low both during May and June 1973, indicating the predominance of the buoyancy effects; (11) There were practically no inversions along the equator; (iii) During May, buoyancy effects were dominant with low friction velocities along 10°N also. But in June forced convection became significant With the increase of friction velocities; (iv) Inversions were observed along 10°N. The, base was observed at higher elevations with weaker inversion strength down streams from 50⁰E to 70° E; (v) Mixed layers were generally unsaturated in both the sections; (vi) Sea surface Virtual temperatures were mostly higher than virtual air temperatures in both the sections; (vii) The drag coefficients were of the order of l x l0^-2; (viii) During a spell of rainfall activity Over India, computations at a stationary site at 10° N, 60.2° E showed high values of positive sea-air temperature differences, generally saturated mixed layers no inversions high specific humidity content; (ix) During a spell of weak rainfall activity over India, however  the computations at the same location showed low sea air temperature difference (often negative), enhanced wind speed lower sea; Surface temperatures, unsaturated mixed layers and daily inversions.