Proceedings with Extended Abstracts (single PDF file) - Radio ...

Report on Session I.3 “Winds, Waves and Turbulence in theLower and Middle Atmosphere and the Lower Thermosphere”Conveners: W. Hocking and M.LarsenSection I.3 was a well attended session, having 26 oral presentations and 7 posters. Topicswere diverse and innovative, covering the accuracy and reliability of wind measurements,new radar methods for wind determination, the dynamics of gravity wave propagation andbreakdown, and methods for using radar to measure the strength of atmospheric turbulence,among others.Wind Measurement Techniques.The first few talks concentrated on the methods of wind measurement Holdsworth and Reiddiscussed the relationship between true and apparent Full Correlation Analysis windvelocities, relative to the IDI (Imaging Doppler Interferometer) method. Theory predictsthat the IDI values should compare best with the apparent velocity, but studies suggest thatthe IDI method often is similar to the true velocity. The reason for this is still a puzzle.Doviak presented a detailed analysis of the errors implicit in the FCA technique, andadvanced the notion that the best FCA methods were often those based on the assumptionon Gaussian correlation functions, rather than the more general assumption that the crosscorrelationfunction and auto-correlation functions should have similar forms. Praskovskyet al. presented an alternative form of spaced antenna analysis, based on a structure functionapproach rather than a correlation function approach. Although both functions contain thesame information, it is presented in a different way, and these authors felt that the requisiteinformation for optimal analysis is best presented by the structure function approach.However, the method uses total powers, rather than complex data, and as such is somewhatmore susceptible to RF interference. This paper was accompanied by a poster paper(I.3.501) which elaborated on the details of the method. Hassenpflug et al. presented erroranalyses associated with determination of correlation length scales using spaced antennatechniques. This parameter is important because it relates to the aspect-sensitivity of thescatterers, and therefore to the degree of anisotropy of atmospheric turbulence at the scalesof the order of half the radar wavelength.Experimental Wind Comparisons.The session then took a more experimental bias, with results of experimental studies ofwind motions being presented by Franke et al. (presented by Hocking) and Hoffman et al.The first showed excellent agreement between meteor winds and lidar winds determined atMauii, and especially noted the frequent existence of wind speeds up to 100 m/s and moreat heights above 90 km. The second paper (Hoffman et al.) studied stratosphericmesosphericinteractions using wind data, especially in regard to stratospheric warmings.Longitudinal variations in mean wind characteristics were noted. A related paper, paperI.3.40, which occurred later in the proceedings, also examined meteor wind and spacedantenna MF winds and noted good correlation between the two techniques. Another related23