VHF radar observations of tropical easterly jet stream over gadanki Original Research Article

The three dimensional wind velocities evaluated using the data obtained from the Indian Mesosphere-Stratosphere-Troposphere (MST) Radar are used to study the tropospheric and lower stratospheric dynamics. Temporal variation of the zonal wind velocities during September 1995 – September 1996 are used to identify and study the tropical easterly jet stream characteristics. The jet is active over the observation site during the months of June, July and August with maximum strength in July. The zonal winds are westerlies upto about 6 km and easterlies start above that height and the maximum winds during jet stream conditions occurred at around 16 km. A reversal in vertical velocities, i.e., descent to ascent, below the jet maximum is observed. Gravity waves generated by the jet induced wind shears are observed with 8 hours periodicity. The wind shears, refractivity turbulence structure constant, Cn2 and the eddy dissipation rate, ε were calculated around the jet stream and the results are presented.