Gravity waves in the mesosphere observed with Wuhan Meteor Radar: A preliminary result

The characteristics of the dominant gravity waves in the vertical profiles of the wind velocities observed in the mesosphere with the Wuhan Meteor Radar, which was setup in February, 2002, are studied. The gravity waves in the mesosphere detected in 2-hourly vertical profiles centered at 6:00LT, when the observation meteor rates reached a maximum, are analyzed by using hodographs. The data used in this study are from February 19 to September 18, 2002. Fifty-one profiles show sinusoidal vertical structure after being smoothed by a band-pass filter with cutoffs at 6km and 15km in order to remove the tides and planetary wave components. There are 55 gravity waves in those profiles. Forty-three waves propagate upward and I I propagate downward. All but 19 gravity waves have a southward component of meridional propagation. The horizontal phase and group velocities are in the range of 15-65 m/s with means of 50.4 m/s and 38.5 m/s,respectively, without significantly monthly variations. The vertical and horizontal wavelengths are mainly from 8 to 12 km, 500 km to 2500 km, with a mean of 10.5 km and 1964 kin. The dominant gravity waves over Wuhan have intrinsic periods from 5 It to 15 h, with a mean of 10.3 h. The averaged wave amplitudes, which decay with height compared with a fixed energy wave, suggest the occurrence of dissipative processes in the middle atmosphere. (C) 2003 COSPAR. Published by Elsevier Ltd. All rights reserved.