Spectra of gravity wave density and wind perturbations observed during Arctic Noctilucent Cloud (ANLC‐93) campaign over the Canadian Prairies: Synergistic airborne Na lidar and MF radar observations

Abstract

The airborne Na lidar and the Saskatoon and Canadian Network for Space Research (CNSR) medium frequency (MF) radars were used to measure the spectra of gravity wave density and wind perturbations during the Arctic Noctilucent Cloud (ANLC‐93) campaign. The National Center for Atmospheric Research Electra flight between Sylvan Lake, Saskatoon, and Great Falls occurred on August 12, 1993. This provided vertical and horizontal wave number spectra for relative atmospheric density fluctuations along the flight legs. Slopes are −2.5±0.1 and −1.3±0.1, respectively, for the vertical and one‐dimensional horizontal wave number spectra. The radars provided temporal frequency and vertical wave number spectra for the flight mission day and duration (July 15 to August 15) of the campaign, so that the fluxes on August 12 could be related to typical summer values. The slopes of frequency spectra are typically −2.1 (1–6 hours) and −1.0 (10–100 min). Gravity wave (GW) parameters from the two observation systems are compared on August 12, including horizontal anisotropies, and dominant horizontal and vertical scale sizes. In particular, several new analyses are developed to illustrate the synergy that is possible between such systems. The radar winds data, using variance ovals and a new correlation‐vector technique, provide evidence for GW propagation into the NE quadrant. This anisotropy of GW propagation is also shown to be evident in the lidar data. An innovative analysis is applied to the Saskatoon MF radar, using Doppler and angle‐of‐arrival data, and used to characterize a unique GW event, which is also observed spatially by the lidar when close to Saskatoon.