Articles | Volume 33, issue 1
https://doi.org/10.5194/angeo-33-101-2015
https://doi.org/10.5194/angeo-33-101-2015
Regular paper
 | 
27 Jan 2015
Regular paper |  | 27 Jan 2015

A dominant acoustic-gravity mode in the polar thermosphere

A. K. Fedorenko, A. V. Bespalova, O. K. Cheremnykh, and E. I. Kryuchkov

Abstract. The article presents a summary of the main findings of the systematic study of acoustic-gravity waves (AGWs) in the polar thermosphere. This study was based on the in situ measurements made by the Dynamics Explorer 2 (DE2) spacecraft late in its mission when it descended low enough (250–400 km). It was found out that AGWs in the polar thermosphere are observed within a narrow frequency band close to the Brunt–Väisälä frequency and with horizontal wavelengths about 500–600 km. The broadband spectrum of travelling ionospheric disturbance (TID) frequencies observed by radars is caused by the Doppler effect. The AGW amplitudes do not depend on the altitude, but grow almost linearly with the wind velocity. They propagate towards the wind.

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Short summary
The article presents a summary of the main findings of the systematic study of acoustic-gravity waves (AGWs) in the polar thermosphere. This study was based on the in situ measurements made by the Dynamics Explorer 2 spacecraft. It was found out that AGWs in the polar thermosphere are observed within a narrow frequency band and with horizontal wavelengths about 500-600km. The connection between the directions of motion of AGW and polar wind circulation was detected.