MESOSPHERE AND LOWER THERMOSPHERE (80-120 KM) WINDS AND TIDES FROM NEAR TROMSO (70-DEGREES-N, 19-DEGREES-E) - COMPARISONS BETWEEN RADARS (MF, EISCAT, VHF) AND ROCKETS

Winds and tides from the MF radar near Tromso are first compared with data from the SOUSY VHF radar near Andenes (69-degrees-N, 16-degrees-E) and from rocket chaff and falling sphere systems, both obtained during SINE (Summer in Northern Europe; 7 June-19 July 1987). Wind directions and tidal phases are in excellent agreement, but magnitudes and amplitudes consistently demonstrate that the MF winds are reduced by 35%. This is associated with reduced signal to noise for the MF radar scatter due to minimal systems (loops) used for the spaced antennas. The adjusted winds and tides are then compared with data obtained from the co-located EISCAT and the Saskatoon MF radars, for a total of six campaigns (1987-1989) covering each season of the year. The data almost overlap near 100 km for three campaigns and do overlap from 90 to 100 km for the other three. There is, in general, excellent agreement between the incoherent scatter and MF radars, and clear seasonal variations are revealed. Differences are attributed to low signal to noise conditions for either radar, lack of complete data overlap, and strong wind gradients in the lower thermosphere.