Looking at the November 20, 2003 super storm with TIMED/GUVI: Comparison with the TIMEGCM

During October and November 2003, Earth was subjected to record-class solar flares and geo-effective coronal mass ejections that caused massive perturbations of the upper atmosphere and ionosphere. Observations of the storm effects are available from the NASA TIMED satellite. Among the four TIMED instruments is the Global Ultra Violet Imager (GUVI), a far ultraviolet (FUV) spectrograph that can be operated in imaging or spectrograph modes. GUVI produces images of the far ultraviolet (FUV) dayglow on both the Earth disk below the satellite and on the limb. Among ionospheric and thermospheric parameters that can be extracted from the imaging data are maps of the atomic oxygen to molecular nitrogen column density ratio and altitude-latitude images of the number density and temperature profiles on the limb. GUVI recorded dramatic changes in these quantities on November 20 and 21, a period when the TIMED orbit was favorable for retrieving composition and temperature from the limb dayglow. We will review GUVI observations during that storm, showing examples of composition and temperature. These will be compared with the initial predictions of the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model. This preliminary comparison reveals many similarities between the model and data. High temperatures seen in the GUVI data are reproduced in the model. And significant perturbations in the composition are also reproduced by the TIMEGCM. But significant differences are also noticed in several areas. In particular, GUVI observes a much less rapid recovery of the perturbed thermosphere than predicted. These and other quantitative conclusions demonstrate that FUV imaging will ultimately play a major role space weather imaging analogous to that of visible or infrared monitoring in tropospheric weather.