Mean winds at 60-90 km observed with the MU radar (35 degrees N)

Mean winds at 60-90 km altitudes observed with the MU radar (35 degrees N, 136 degrees E) in 1985-1989 are presented in this paper. The zonal wind at 70 km became westward and eastward in summer and winter, respectively, with a maximum amplitude of 45 m s(-1) westward in early July and 80 m s(-1) eastward at the end of November. The meridional wind below 85 km was generally northward with the amplitude less than 10 m s(-1). In September to November, the meridional wind at 75-80 km becomes as large as 20-30 m s(-1) Those zonal wind profiles below 90 km show good coincidence with the CIRA 1986 model, except for the latter half of winter, from January to March, when the observational result showed a much weaker eastward wind than the CIRA model. The height of the reversal of the summer wind from westward to eastward was determined as being 83-84 km, which is close to the CIRA 1986 model of 85 km. The difference between the previous meteor radar results at 35-40 degrees N, which showed the reversal height below 80 km, could be due to interannual variations or the difference in wind measurement technique. In order to clarify that point, careful comparative observations would be necessary. These mean winds were compared with Adelaide MF radar observations, and showed good symmetry between the hemispheres, including the summer reversal height, except for the short period of eastward winds above Kyoto and the long period over Adelaide.