MEASUREMENTS OF SUPERADIABATIC LAPSE RATES IN THE MIDDLE ATMOSPHERE

A large power-aperture product Rayleigh-scatter lidar system has been successfully built and over 175 nights of middle atmosphere temperatur e measurements have been obtained. The high signal-to-noise ratio of t hese measurements allows the stability of the air in the upper stratos phere and mesosphere to be determined. A detailed methodology has been developed to attempt to differentiate between lapse rate variations d ue to photon counting errors and actual geophysical variations. On nig hts when the geophysical variations are large compared to the photon c ounting errors, regions of convective stability and instability can be determined at a reasonably high confidence level. Both statistics of the layers and an ''image'' of the layers is presented for the night o f May 31, 1996. The measured percentage of unstable layers is in agree ment with the predictions of Hines (1991), as is the apparently sporad ic formation and distribution of the unstable regions.