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The Communications Research Laboratory (CRL) has operated the Wakkanai MF radar since September of 1996, and Yamagawa MF radar since August of 1994. Recent observation results on variations of mean wind, wind spectra and diurnal wind oscillations during a strong eastward wind, comparison experiments with the MU radar and rockets, and D-region electron density measurements by MF radar are summarized briefly. The spectra comparison of two MF radar observations show a high degree of spatial and temporal variability in a winter mesosphere in Northern and Southern Japan. Differences of mean wind in 1997 between both sites are shown for the periods of solstices and equinoxes. It is suggested that the propagation of the diurnal tide from the mesosphere into the dynamo region is disturbed by the sudden enhancements of the strong eastward wind.

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