Comparisons Between TIME-GCM/MERRA Simulations and LEO Satellite Observations

Friday, 19 December 2014
Kathrin Haeusler, NCAR / HAO, Boulder, CO, United States, Maura E Hagan, National Center for Atmospheric Research, Boulder, CO, United States, Jeffrey M Forbes, University of Colorado at Boulder, Boulder, CO, United States, Xiaoli Zhang, UCB 429, Boulder, CO, United States, Eelco Doornbos, Delft University of Technology, Aerospace Engineering, Delft, Netherlands, Sean Bruinsma, CNES French National Center for Space Studies, Toulouse Cedex 09, France and Gang Lu, National Center for Atmospheric Research, High Altitude Observatory, Boulder, CO, United States
We report on yearlong National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM) simulations where we utilize the recently developed lower boundary condition based on 3-hourly MERRA (Modern-Era Retrospective Analysis for Research and Application) reanalysis data to account for tropospheric waves and tides propagating upward into the model domain. The solar and geomagnetic forcing is based on prevailing geophysical conditions. The simulations show a strong day-to-day variability in the upper thermospheric neutral temperature tidal fields, which is smoothed out quickly when averaging is applied over several days, e.g. up to 50% DE3 amplitude reduction for a 10-day average. This is an important result with respect to tidal diagnostics from satellite observations where averaging over multiple days is inevitable. In order to assess TIME-GCM performance we compare the simulations with measurements from the Gravity field and steady-state Ocean Circulation Explorer (GOCE), Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites.