THERMOSPHERIC MERIDIONAL WINDS IN THE VICINITY OF THE AURORAL-ZONE - OBSERVATIONS AND MODELING

Optical Fabry-Perot interferometer measurements of the Doppler shift o f the 557.7 nm OI emission were used to obtain the meridional thermosp heric wind velocities at heights of the E-layer in the pre-midnight se ctor of the ionosphere at Loparskaya (68 degrees N. 33 degrees E geogr aphic). They distinctly reveal a decrease in the mean meridional wind velocity when passing across the auroral zone from the pole to the equ ator, and also the near-counterphase character of the wind velocity fl uctuations on both sides of the precipitation zone. The observed behav iour of the meridional wind has been reproduced in the modelling calcu lations using the global ionosphere-thermosphere model and interpreted in terms of the ion-neutral coupling due to the momentum interchange and generation of atmospheric internal gravity waves. (C) 1998 Elsevie r Science Ltd. All rights reserved.