Abstract
Abstract. The Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) is a self-consistent, global, atmospheric model that can be used to estimate magnetic perturbations at satellite altitude. These computed perturbations can then be compared with the magnetic vector data provided by low-earth orbiting satellites. In this initial study, the quietest day of each month from 2001–2005 was selected for comparison. CHAMP magnetic vector residuals were computed for these intervals using the CHAOS model to remove core and crustal geomagnetic contributions. Under various input parameters, the TIE-GCM predictions were compared with the CHAMP residuals on an orbit by orbit basis. Initial results demonstrate a reasonable agreement between the TIE-GCM estimates and the CHAMP residuals in non-polar, dayside regions (±50° magnetic latitude) where both are able to resolve the Equatorial Electro-Jet (EEJ) and solar quiet (Sq) current systems. Although no clear component or temporal correlation was discerned, evidence showing the decrease in residual comparisons presents the possibility of using the TIE-GCM to pre-process geomagnetic data for main field modeling purposes.
Highlights
When either a magnetic observatory or a satellite records a geomagnetic field measurement, it represents the superposition of many sources
In this paper we show that the Thermosphere-Ionosphere Electrodynamics General Circulation Model (TIE-GCM) model can, to some degree, reproduce the residuals computed from Challenging Minisatellite Payload (CHAMP) geomagnetic vector data, and that it might be possible to use the TIE-GCM to pre-process dayside satellite data in order to supplement geomagnetic modeling efforts, especially when there is a scarcity of quality data
The results presented here were obtained by varying different parameters in the TIE-GCM magnetic perturbation computation and are detailed in the remainder of the section
Summary
When either a magnetic observatory or a satellite records a geomagnetic field measurement, it represents the superposition of many sources. Butions from the static lithospheric field, originating largely from rocks within the Earth’s crust. Another significant portion comes from external field sources, which are produced in the ionosphere and magnetosphere. In satellite data it is even possible to resolve small signals attributable to the electrical currents generated by ocean flow (Tyler et al, 2003). Most of these field sources undergo temporal variations, both periodic and non-periodic, ranging from the secular variation of the main field on decadal scales down to the sub-second variations during geomagnetic storms in the magnetosphere
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