Detection and Mitigation of Geomagnetic Pulsation Effects Using GPS

S. Skone, N. Nicholson

Abstract:	Magnetic Anomaly Detection (MAD) is an application in which airborne magnetometers are used to detect small magnetic variations against the Earth’s background magnetic field. This technique is used in aeromagnetic surveys, to detect mineral deposits, and applications such as antisubmarine warfare. The magnetic signals of interest typically have periods of 1-100 s and amplitudes of 0.001-1 nT. In order to isolate and detect such signals, all other sources of magnetic noise in this frequency band must be modeled, or measured, and mitigated. Despite reduction of many error sources for MAD, a limiting factor remains – the small-amplitude variations caused by geomagnetic pulsations. In the frequency band of interest for MAD (0.01-1Hz), Pc 3 pulsations represent a significant error source. These continuous pulsations are apparent as pulse trains in magnetic time series for intervals as long as several minutes. These pulsations arise from resonant oscillations in the dayside magnetosphere driven by the solar wind. For compressional Pc 3, plasma density variations occur in the Earth’s ionosphere. Such fluctuations may be observed in GPS total electron content (TEC) observations. In this paper we present preliminary investigations for detection of geomagnetic pulsations using GPS. Due to the very small amplitude of these TEC variations, it is critical to minimize all sources of error in the TEC observations. Relative TEC variations are derived from the precise dual-frequency GPS carrier phase observations and bandpass filtered. Correlations of TEC series are computed, for two closely-spaced GPS receivers and for two satellites at similar azimuth and elevation, to identify common ionosphere signals. Results for two case study events indicate that TEC variations associated with geomagnetic pulsations may be observed under limited conditions.
Published in:	Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006) September 26 - 29, 2006 Fort Worth Convention Center Fort Worth, TX
Pages:	1393 - 1401
Cite this article:	Skone, S., Nicholson, N., "Detection and Mitigation of Geomagnetic Pulsation Effects Using GPS," Proceedings of the 19th International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2006), Fort Worth, TX, September 2006, pp. 1393-1401.
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