Measurements of Intermittency in the Upper Stratosphere and Mesosphere

Abstract

Measurements of the gravity wave spectrum in the upper stratosphere and mesosphere are scarce compared to those in the troposphere and lower thermosphere, which are easier to probe via in situ and remote sensing techniques. This paucity of measurements impacts the parameterization of gravity waves in general circulation models of the middle atmosphere, since the effects of gravity waves are not adequately constrained by measurements. The development of a larger power-aperture product lidar at The University of Western Ontario has allowed the measurement of the gravity wave spectrum at high temporal-spatial resolution. These measurements have been used to impact three key areas relevant to parameterizations: the thermodynamic perturbations caused by gravity waves, the variability of the spatial and temporal spectra and the estimation of the eddy diffusion coefficient. After a brief introduction to the instrumentation (Section 2), Section 3 describes an extension of the initial measurements of superadiabatic lapse rates by Sica and Thorsley (1996a). A taste of the spatial and temporal spectral retrievals possible with the lidar measurements is given in Section 4. In Section 5, the spectra are used to calculate energy dissipation and the eddy diffusion coefficient.