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EP: Fachverband Extraterrestrische Physik
EP 4: Near Earth Space II
EP 4.2: Vortrag
Dienstag, 31. August 2021, 17:00–17:15, H8
The mid-to high-latitude migrating semidiurnal tide: Results from SuperDARN meteor wind observations and mechanistic simulations — •Willem van Caspel1,2 and Patrick Espy1,2 — 1Norwegian University of Science and Technology, Trondheim, Norway — 2Birkeland Centre for Space Science, Bergen, Norway
Meteor wind observations of the migrating semidiurnal tide (SW2) made by a longitudinal chain of high-latitude SuperDARN radars are compared against simulations made using a mechanistic primitive equation model. The model is a three-dimensional, non-linear and time-dependent spectral model. The modeled background zonal mean zonal winds and temperatures are nudged to daily mean data from the Navy Global Environmental Model - High Altitude (NAVGEM-HA) meteorological analysis system up to ∼95 km altitude. The SW2 tide is forced using 3-hourly temperature tendency fields from the Specified Dynamics Whole Atmosphere Community Climate Model With Thermosphere and Ionosphere Extension (SD-WACCMX). To compare the model to observation, the model is sampled according to the meteor echo distribution of the SuperDARN radars at the locations of available measurements for the year 2015. Our model accurately reproduces the observed seasonal variations in the SW2 amplitude and phase. Model experiments are performed to investigate the role of the background atmosphere, tidal forcing, and dissipation terms in establishing the simulated SW2 tide. Notably, the dissipation terms include a seasonally varying mesospheric eddy diffusion, and a surface friction layer.