The Effects of Solar/Geomagnetic Storms on RadCal Ephemeris Solutions

J.T. Saffel, C.F. Minter, S.P. Simmons, and J.W. Stevens

Abstract:	The GPS Division at the National Geospatial-Intelligence Agency’s Office of GEOINT Sciences supports the Air Force, Army, Navy, and NASA major missile test ranges by estimating the Radar Calibration (RadCal) satellite ephemeris. The major ranges use the GPS Division’s RadCal ephemeris to calibrate their radar tracking systems. Because the GPS Division has been performing these calculations continuously since the beginning of the last solar cycle in 1999, RadCal makes an ideal platform for studying the effects of solar/geomagnetic storms on satellite ephemeris calculations. During solar events, increased heating causes an expansion of the upper atmosphere into low-Earth-orbit, which in turn increases satellite drag. The RadCal ephemeris shows strong correlations between increased satellite drag and solar/geomagnetic activity. Furthermore, radio signal propagation becomes noisier during these storm events, affecting RadCal observations and radar system accuracy. Results show strong correlations between increased observation noise and solar/geomagnetic storm events.
Published in:	Proceedings of the 2010 International Technical Meeting of The Institute of Navigation January 25 - 27, 2010 Catamaran Resort Hotel San Diego, CA
Pages:	433 - 439
Cite this article:	Saffel, J.T., Minter, C.F., Simmons, S.P., Stevens, J.W., "The Effects of Solar/Geomagnetic Storms on RadCal Ephemeris Solutions," Proceedings of the 2010 International Technical Meeting of The Institute of Navigation, San Diego, CA, January 2010, pp. 433-439.
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