ANGEO

Annales Geophysicae

ANGEO

Ann. Geophys.

1432-0576

Springer Verlag

Göttingen, Germany

10.1007/s00585-000-0547-3

Intradiurnal wind variations observed in the lower thermosphere over the South Pole

Portnyagin

Y. I.

¹ ³ Forbes

J. M.

² Merzlyakov

E. G.

¹ Makarov

N. A.

¹ Palo

S. E.

Institute for Experimental Meteorology, 82, Lenin st., Obninsk, Kaluga region, 249020, Russia

Department of Aerospace Engineering Sciences, Campus Box 429, University of Colorado, Boulder, CO 80303-0429 USA

Correspondence to: Y. I. Portnyagin

31 05 2000

18 5 547 554

2000

This article is available from https://angeo.copernicus.org/articles/18/547/2000/angeo-18-547-2000.html

The full text article is available as a PDF file from https://angeo.copernicus.org/articles/18/547/2000/angeo-18-547-2000.pdf

The first meteor radar measurements of meridional winds in the lower thermosphere (about 95 ± 5 km), along four azimuth directions: 0°, 90°E, 180° and 90°W; approximately 2° from the geographic South Pole were made during two observational campaigns: January 19, 1995-January 26, 1996, and November 21, 1996-January 27, 1997. Herein we report analyses of the measurement results, obtained during the first campaign, which cover the whole one-year period, with particular emphasis on the transient nature and seasonal behavior of the main parameters of the intradiurnal wind oscillations. To analyze the data, two complementary methods are used: the well-known periodogram (FFT) technique and the S-transform technique. The most characteristic periods of the intradiurnal oscillations are found to be rather uniformly spread between about 7 h and 12 h. All of these oscillations are westward-propagating with zonal wave number s=1 and their usual duration is confined to several periods. During the austral winter season the oscillations with periods less than 12 h are the most intensive, while during summer season the 12-h oscillations dominate. Lamb waves and internal-gravity wave propagation, non-linear interaction of the short-period tides, excitation in situ of the short period waves may be considered as possible processes which are responsible for intradiurnal wind oscillations in the lower thermosphere over South Pole. Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics; waves and tides)