MESOSPHERIC WIND STUDIES DURING AIDA-ACT-89 - MORPHOLOGY AND COMPARISON OF VARIOUS TECHNIQUES

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 in coherent scatter radar (ISR) measurements with those of a 3.175 MHz ra dar operating as an imaging Doppler interferometer (IDI). We have perf ormed further analyses in order to justify the interpretation of the l ong term IDI measurements in terms of prevailing winds and tides. Init ial comparison of 14 profiles by Hines et al, 1993, J atmos terr Phys 55, 241-288, showed good agreement between the ISR and IDI measurement s up to about 80 km, with fair to poor agreement above that altitude. We have compiled statistics from 208 profiles which show that the prev ailing wind and diurnal and semidiurnal tides deduced from the IDI dat a provide a background wind about which both the IDI dat provide a bac kground wind about which both the IDI and ISR winds are normally distr ibuted over the height range from 70 to 97 km. The 3.175 MHz radar dat a have also been processed using an interferometry (INT) technique Va n Baelen and Richmond 1991, Radio Sts 26, 1209-1218 and two spaced an tenna (SA) techniques Meek, 1980, J atmos terr Phys 42, 837-839, Brig gs, 1984, MAP Handbook, Vol 13, pp 166-186 to determine the three dim ensional wind vector. These are then compared with the IDI results. Ti dal amplitudes and phases were calculated using the generalized analys is of Groves, 1959, S atmos terr Phys 16, 344-356, historically used o n meteor wind radar data. Results show a predominance of the diurnal S -VERTICAL-BAR tidal mode in the altitude range 70-110 km, reaching a m aximum amplitudes 45 ms(-1) at 95 km, with semidiurnal amplitudes bein g 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 o n the order of 20 ms(-1).