The Summer Wind Field Between 80 and 93 km Observed by the MST Radar at Poker Flat, Alaska (65°N)

Abstract

Results of an analysis of the summertime wind field between 80?93 km over Poker Flat, Alaska are presented. The data were obtained using the large, but as yet incomplete, MST radar at Poker Flat, and cover the periods 17 June?13 July 1979, and 22 June?22 July 1980. Zonal and meridional mean wind profiles and ?tidal? components during these periods are examined and are compared with other observations at comparable latitudes as well as with current theoretical profiles. While our results agree reasonably closely with other observations and theory, some discrepancies exist and are discussed. In addition to the expected 8, 12 and 24 h components of atmospheric motions, we find strong evidence for a 16 h component, particularly during the 1979 data period. In addition, we show examples of the average power spectrum of wind fluctuations from 3 min to 8 days. These spectra not only show the expected ?tidal? peaks, but show also that the spectral energy density is continuous between the shortest (8 h) tidal period and the shortest observed period (3 min), falling off with an f?5/3 power law. Some aspects of these spectral results are discussed, including the possible processes that may operate to produce such a spectral shape.