CLIMATOLOGIES OF TIDAL WINDS IN THE RADIO-METEOR REGION OVER TRIVANDRUM (8-DEGREES-N)

The climatologies of tidal wind fields in the 80-105 km region using M eteor Wind Radar (MWR) observations during June 1984-1988 at Trivandru m (8.5 degrees N) are presented. The most significant feature revealed by the amplitude and phase profiles of the tidal winds is the simulta neous presence of two modes, differing in vertical wavelengths, for ea ch oscillation. In contrast to the expected (1,1) mode, the (1,-2) diu rnal mode is found to be stronger. In addition to the stronger (2,2) s emi-diurnal mode, higher order modes are also found to be significant. The 24 h oscillation is found to be the strongest component and 12 h and 8 h oscillations are equally significant. The tidal wind amplitude s over Trivandrum are found to be larger during the equinoctial months . The amplitudes and vertical wavelengths of the two interfering modes of the 24 h, 12 h, 8 h oscillations are deduced and compared with our current theoretical understanding on tidal winds and observations fro m other low latitude stations. (C) 1997 Elsevier Science Ltd.