Wide Area Ionosphere Modeling in the Equatorial Region during a Magnetic Storm Event

S. Skone

Abstract:	Dual frequency GPS receivers enable the estimation of absolute ionospheric delay and total electron content (TEC) along the satellite-receiver signal path. By using a number of reference stations, each equipped with a dual frequency receiver, it is possible to estimate values of the vertical ionospheric delay at a set of designated grid points (in latitude and longitude) on an ionosphere shell. This type of ionosphere delay modeling is employed in wide area differential GPS (WADGPS) networks. Wide area ionosphere models can suffer degraded performance in regions where large spatial gradients (and temporal variations) in TEC exist. One such area is the equatorial region, where electrons are lifted away from the magnetic equator, under the influence of strong electric fields. Large TEC gradients are present near the resulting equatorial anomaly. These gradients can be enhanced during periods of magnetic storm activity, and such effects are a concern for the reliable implementation of WADGPS networks (i.e. safety-critical systems such as WAAS). In this paper, wide area ionosphere grid accuracies are investigated in the equatorial region during an August1998 magnetic storm event. This storm evolved over several days, and a detailed analysis of the event is conducted through observations of various space weather parameters. GPS observations from eight stations in the Brazilian geodetic network are used to calculate TEC variations near the equatorial anomaly, and spatial gradients associated with the storm event are determined. Network observations are included in grid adjustments for different grid spacings, and relative accuracies of VTEC estimates are assessed.
Published in:	Proceedings of the 2000 National Technical Meeting of The Institute of Navigation January 26 - 28, 2000 Pacific Hotel Disneyland Anaheim, CA
Pages:	481 - 489
Cite this article:	Skone, S., "Wide Area Ionosphere Modeling in the Equatorial Region during a Magnetic Storm Event," Proceedings of the 2000 National Technical Meeting of The Institute of Navigation, Anaheim, CA, January 2000, pp. 481-489.
Full Paper:	ION Members/Non-Members: 1 Download Credit Sign In