The Arecibo Initiative in Dynamics of the Atmosphere (AIDA) '89 was a multi-instrument campaign designed to compare various mesospheric wind measurement techniques. Our emphasis here is the comparison of the incoherent scatter radar (ISR) measurements with those of a 3.175 MHz radar operating a s an imaging Doppler interferometer (1131). We have performed further analyses in order to justify the interpretation of the long term IDI measurements in terms of prevailing winds and tides. Initial comparison of 14 profiles by Hines et al., 1993, J. atmos. terr. Phys. 55, 241–288, showed good agreement between the ISR and IDI measurements up to about 80 km, with fair to poor agreement above that altitude. We have compiled statistics from 208 profiles which show that the prevailing wind and diurnal and semidiurnal tides deduced from the IDI data provide a background wind about which both the IDI and ISR winds are normally distributed over the height range from 70 to 97 km. The 3.175 MHz radar data have also been processed using an interferometry (INT) technique [Van Baelen and Richmond 1991, Radio Sts. 26, 1209–1218] and two spaced antenna (SA) techniques [Meek, 1980, J. atmos. terr. Phys. 42, 837–839; Briggs. 1984, MAP Handbook, Vol. 13, pp. 166–186] to determine the three dimensional wind vector. These are then compared with the IDI results. Tidal amplitudes and phases were calculated using the generalized analysis of Groves, 1959, S. atmos. terr. Phys. 16, 344–356, historically used on meteor wind radar data. Results show a predominance of the diurnal S11 tidal mode in the altitude range 70–110 km, reaching a maximum amplitude 45 ms−1 at 95 km, with semidiurnal amplitudes being about 10–15 ms−1 throughout the height range considered. There is evidence of the two day wave in data from 86–120 km, with amplitudes on the order of 20 ms−1.
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