NEUTRAL WIND OBSERVATION IN 1985 BY THE SYOWA STATION METEOR RADAR

• Main Authors: オガワ タダヒコ, タナカ タカシ, イガラシ キヨシ, フジイ リョウイチ, Tadahiko OGAWA, Takashi TANAKA, Kiyoshi IGARASHI, Ryoichi FUJII
• Format: Report
• Language: English
• Published: ABSTRACT 1987
• Subjects: Syowa Station; Antarc*; Antarctica; E. Antarctica; Polar meteorology and glaciology; Proceedings of the NIPR Symposium on Polar Meteorology and Glaciology
• Online Access: https://nipr.repo.nii.ac.jp/?action=repository_uri&item_id=3540; http://id.nii.ac.jp/1291/00003540/; https://nipr.repo.nii.ac.jp/?action=repository_action_common_download&item_id=3540&item_no=1&attribute_id=18&file_no=1

Neutral winds at altitudes of 80-100km were almost continuously observed in 1985 using a 50MHz meteor radar located at Syowa Station (69.0°S, 39.6°E), Antarctica. The radar has a nominal peak power of 15kW and narrow antenna beams (about 4° in the horizontal plane) in two directions (approximately geomagnetic and geographic south) with a crossing angle of 33°. It is possible to deduce a two-dimensional wind pattern from wind data obtained by each antenna beam. During an auroral substorm, the radar often detected auroral echoes, in addition to meteor echoes, due to the electron density irregularities in the E-region. By examining carefully individual echo data stored on digital magnetic tapes, the auroral echoes were removed and only the meteor echoes were collected for the analysis. Hourly and monthly variations of north-south and east-west winds versus altitude (79-99km) were calculated. The diurnal and semi-diurnal components are discernible in the hourly variation. The monthly variation is more complicated than that from the CIRA 1972 model at 70°S, though the fundamental characteristics such as westward flow in summer and eastward flow in winter are similar to each other. Also found are the higher wind velocities above 90km, which may be partly affected by the strong electric fields in the E-region during substorms. In 1985 the lidar observations of the mesospheric sodium layer were also made at Syowa Station. It is found that the temporal fluctuations of the sodium abundance are sometimes correlated with the neutral wind fluctuations. This fact demonstrates clearly that atmospheric gravity waves are one of the important factors modifying the mesospheric sodium layer.