Statistical Characterization of GITM Thermospheric Horizontal Winds in Comparison to GOCE Estimations
Michigan Tech Research Institute
Characterization of the thermospheric horizontal wind is an important challenge in atmospheric modeling due to its vital role in the transport of densities and energy, associations with the diurnal tide, and interplay with vertical winds that drive changes in the thermosphere neutral composition. The mechanisms and drivers that underlie the physics of thermospheric horizontal winds remain under investigation and, to date, no comprehensive statistical study between thermospheric winds generated by a physics-based atmospheric model and those retrieved from satellite measurements has been performed. Comparisons between cross-track horizontal winds from a 10-month run of Global Ionosphere-Thermosphere (GITM) and those derived from the Gravity field and steady-state Ocean Circulation Explorer (GOCE) satellite show that GITM did best modeling horizontal winds in the polar zone but overestimated horizontal wind speeds at midlatitudes just outside of the equatorial ionization anomaly region. GITM's wind response to AE was best at polar noon and worst in the midnight auroral zone, its ability to capture seasonality was best in the northern high latitudes and worst in the southern high latitudes, and GITM displayed less wind variability as a function of F10.7 than GOCE, matching it best for F10.7 >∼150. Discrepancies in GITM's performance may be explained by inaccurate modeling of ion drift, ion drag, and electron densities.
Statistical Characterization of GITM Thermospheric Horizontal Winds in Comparison to GOCE Estimations.
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