Simultaneous mesospheric wind measurements near South Pole by optical and meteor radar methods

Simultaneous and co-located measurements of mesospheric winds near South Pole, by high-resolution optical and meteor radar methods, show that these two methods determine very similar motions at slightly different heights of observation. The measured atmospheric motions by the two techniques show that a) The mean wind during 12 days in June, 1995 was found to have a 7 m/s amplitude flowing towards the 5 degrees E longitude direction. The latter direction is different from the 30E degrees direction found earlier during August 1991 and 1992. b) The observed dominant oscillations in the wind at both heights of observation are those of zonal wavenumber one character. Westward phase propagation was determined for the observed short-period (similar to 10 hours) oscillations and eastward phase propagation for the longer-period (similar to 3 days) oscillations, respectively. Because of the neighboring heights of observation by the optical and meteor radar methods, the in situ vertical wavelengths of propagation of the observed waves have been determined to be greater than 100 km for the 10-hr oscillations and near 65 km for the longer period oscillations. With this new information we are able to independently establish the earlier assignment of the nearly 10-hr oscillations as the different meridional modes of a zonal wavenumber one Lamb wave. The determined vertical wavelength and eastward phase progression of the longer periodicity waves indicate these oscillations are likely to be the gravest inertio-gravity wave, which has the appropriate equivalent depths at these periods of oscillation. The simultaneous absence of statistically significant kinetic temperature and optical-tracer emission rate oscillations at the frequencies corresponding to the wind motions, provides independent support to the earlier deductions on the ability of the atmosphere near the rotational poles to support only certain zonal character oscillations.