Characteristics of composite low level jet over the Arabian Sea during the spell 21-27 June of Monsoon Experiment (MONEX), 1979

Abstract

The paper reveals the existence of the composite low level jet over the Arabian Sea in the latitudinal belt of 8 deg. and 12 deg. N from longitude 56 deg. E to 66 deg. E based on MONEX-1979 data during the spell 21-27 June 1979, when no low level disturbance is present over the region.

It is observed that during the spell the low level jets have two branches and the lower branch is a broad band of low-level jet with great longitudinal span embedded in strong westerly zonal flow and divergence field.

An examination of the composite mean tephigrams during the spell reveals that the low level jets at 850 mb level occur mostly at the boundary of moist and dry air masses with saturated adiabatic lapse aloft. To test the reliability of the ideas reported so far in the light of the present investigation some of the results of the composite low level jet have been compared with observations mainly those by Desai et at. (1976) based on individual case studies of the low level jet and the results compare favourably well in some aspects.