Assessment of the Higher Order Ionosphere Error on Position Solutions

Y.T. Morton, Frank van Graas, Qihou Zhou, Jeffrey Herdtner

Abstract:	This paper presents an assessment of the impact of the higher order ionosphere error on GPS position solutions. Prior studies have shown that the second order ionosphere error is on the order of a few cm under quiet conditions and may reach a few tens of cm during geomagnetically disturbed periods while the third order error is typically below a few mm. These conclusions were drawn based on simplified ionosphere models. Furthermore, there is a lack of understanding on the temporal and spatial structure of the higher order error. In this paper, we take a fundamental approach in analyzing the ionosphere higher order error and its impact on a GPS receiver solution by applying the Appleton-Hartree formula in the computation of the higher order errors. Instead of using simplified ionosphere models, we combine high resolution time and altitude vertical electron density profiles obtained from the Arecibo incoherent scatter radar, the International Reference Ionosphere model, total electron content maps derived from the CORS network of dual frequency GPS receiver measurements and the International Geomagnetic Reference Field model in the study. The 24-satellite Martinez constellation is used to compute a receiver position error based on second and third order range error results. The position error for a receiver located at the Arecibo radar site on a quiet day is used as an example to demonstrate the magnitude, sign, and daily variation patterns of the higher order ionosphere error.
Published in:	Proceedings of the 21st International Technical Meeting of the Satellite Division of The Institute of Navigation (ION GNSS 2008) September 16 - 19, 2008 Savannah International Convention Center Savannah, GA
Pages:	2361 - 2369
Cite this article:	Updated citation: Published in NAVIGATION: Journal of the Institute of Navigation
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