Comparison of wind measurements between Yamagawa MF radar and the MU radar

A new MF radar was installed at Yamagawa (31.20 degrees N, 130.62 degrees E), Japan in August, 1994 by the Communications Research Laboratory, and the first comparison of wind measurements taken with the Yamagawa MF radar and meteor wind measurements with the MU radar at Shigaraki (34.85 degrees N, 136.10 degrees E) are carried out. In spite of their spatial separation of approximately 650 km, reasonable agreement between wind velocities by the two radars at 80 - 92 km in altitude is confirmed, except for small scale perturbations that are probably due to gravity waves enhanced for the period from 17 h LT on September 13 to 7 h LT on September 14, 1994. It is found that the winds of the MF radar above 92 km tend to be smaller than the winds obtained with the MU radar. Receiver saturation and interference are possible causes of the reduced wind velocities observed with the MF radar. The height structures of semidiurnal tides are also compared. The amplitude and phase of zonal components agree at most heights between the two radars. For the meridional component the amplitudes fluctuate above 88 km with a significant difference and the phase from the MU radar leads that of the MF radar by less than several hours at 86 km to 92 km. An enhanced gravity wave seems to pass over the MU radar almost from north to south, resulting in a contamination of the meridional wind component of the semidiurnal variation.