Intradiurnal wind variations observed in the lower thermosphere over the

• Main Authors: South Pole, Y. I. Portnyagin, J. M. Forbes, E. G. Merzlyakov, N. A. Makarov, S. E. Palo
• Other Authors: The Pennsylvania State University CiteSeerX Archives
• Format: Text
• Language: English
• Published: 1998
• Subjects: waves and; Austral; South Pole; South pole
• Online Access: http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.590.8304; http://www.ann-geophys.net/18/547/2000/angeo-18-547-2000.pdf

Abstract. The first meteor radar measurements of me-ridional 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 cam-paigns: January 19, 1995–January 26, 1996, and No-vember 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 intra-diurnal 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 oscilla-tions 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 thermo-sphere over South Pole. Key words: Meteorology and atmospheric dynamics (middle atmosphere dynamics; thermospheric dynamics;