Earth Planets Space, Vol. 51 (Nos. 7, 8), pp. 691-689, 1999
Masaki Tsutsumi1, David Holdsworth2, Takuji Nakamura3, and Iain Reid4
1National Institute of Polar Research, Tokyo, Japan
2Atmospheric Radar Systems, Adelaide, Australia
3Radio Atmospheric Science Center, Kyoto University, Uji, Kyoto, Japan
4University of Adelaide, Adelaide, Australia
(Received August 19, 1998; Revised June 6, 1999; Accepted June 10, 1999)
Abstract: We conducted meteor echo observations using the Buckland Park MF radar (35°S, 138°E) at 00:40-05:45 LT on October 22, 1997. In addition to the usual full correlation analysis (FCA) technique to measure horizontal wind velocities from 60 to 100 km MF radars have a potential to detect meteor echoes and infer winds through their Doppler frequency shifts. Because of the relatively low radio frequency employed MF radars have a great advantage of providing meteor wind well above 100 km altitude, where very few techniques can measure wind velocities. There is a limitation which should be noted as well. The observations are possible only during night time when the electron density of E-region is low enough for the radio wave to penetrate into the upper region. We detected 233 underdense meteor echoes from 80 km to 120 km with a mean height of 104.4 km. Although the transmitting antenna beams were steered toward off-zenith angles of 25°, almost all the echoes were received outside of the main lobe, indicating that conventional MF radar systems with a broad transmitting beam can work well for meteor observations. Bi-hourly wind profiles were obtained from 94 to 114 km altitudes. The profiles revealed a clear wave structure with a downward phase progression with time. FCA winds from 80 to 100 km were also estimated, and a continuous wind structure was obtained from FCA to meteor heights. Note that the present observations happened to be conducted during a major meteor shower activity. However, a majority of the underdense echoes were from non-shower meteors, and observations during non-shower periods will also yield enough information.