Comparison of Conductances derived from IDA3D and TIMEGCM with GUVI

The Global Ultraviolet Imager (GUVI) instrument on the TIMED satellite measures various auroral parameters including the energy and flux distributions, which can then be used to estimate auroral conductances. In this paper, we compare GUVI conductances with those obtained from an ionospheric data assimilation imaging algorithm. The comparison is focused on the Alaska region, where five tomographic receivers collected data during the November 6 14, 2004 study period, which contained both quiet days and a large magnetic storm. The receivers were arrayed across Central Alaska from ~ 60 70 degrees of latitude. The Ionospheric Data Assimilation Three-Dimensional (IDA3D) tomographic imaging algorithm was run for this period using the Thermosphere Ionosphere Mesosphere Electrodynamics General Circulation Model (TIMEGCM) as a background model, driven by convection and precipitation patterns obtained from the Assimilative Mapping of Ionospheric Electrodynamics (AMIE) procedure. In addition to the Alaska tomography data, IDA3D also ingested ground-based GPS data, low earth orbiting (LEO) satellite GPS occultation data and over-satellite electron content data, in-situ measurements of electron density from DMSP and CHAMP, incoherent scatter radar data and ionosonde data. IDA3D was run twice for the study period, with 5 minute cadence. The first run ingested all the data except the Alaska tomography data. The second run used all the data, including the Alaska tomography data. The study shows the value of the tomography data, and the kind of detailed ionospheric structure that can be obtained from IDA3D, which is particularly useful in complex highly structured situations.