Large-scale gravity wave perturbations in the mesopause region above Northern Hemisphere midlatitudes during autumnal equinox: a joint study by the USU Na lidar and Whole Atmosphere Community Climate Model

摘要

To investigate gravity wave (GW) perturbations in themidlatitude mesopause region during boreal equinox, 433 h of continuousNa lidar full diurnal cycle temperature measurements in September between2011 and 2015 are utilized to derive the monthly profiles of GW-inducedtemperature variance, ′, and the potential energy density (PED).Operating at Utah State University (42° N, 112° W),these lidar measurements reveal severe GW dissipation near 90 km, where bothparameters drop to their minima (∼ 20 K and ∼ 50 m s, respectively). The study also shows thatGWs with periods of 3–5 h dominate the midlatitude mesopause region duringthe summer–winter transition. To derive the precise temperatureperturbations a new tide removal algorithm suitable for all ground-basedobservations is developed to de-trend the lidar temperature measurements andto isolate GW-induced perturbations. It removes the tidal perturbationscompletely and provides the most accurate GW perturbations for the ground-based observations. This algorithm is validated by comparing the true GWperturbations in the latest mesoscale-resolving Whole Atmosphere CommunityClimate Model (WACCM) with those derived from the WACCM local outputs byapplying this newly developed tidal removal algorithm.