Review of Mapping Functions Proposed to Predict the Delay at Very Low Elevation Angles

I.M. Ifadis, P. Savvaidis

Abstract:	The principal limiting error in modem space geodesy techniques is the mismodeling of the atmospheric delay. This delay, usually separated and referred as hydrostatic (dry) and W* is descrii as the product of its value at the zenith aud a fimction which scales its elevation dependence. Accordingly there are proposed fimctions first for the prediction of the zenith delay (very accumte fix the &y component) ad then fbr scaling this value at other elevations. During the last @ years, under the assumption of a spherically stmtitied atmosphere, a number of fimctions were developed using various types of data. Some of theme are using surface meteorological observations during the time of masmmenis and others time or geographical data. They are commonly based on the Hopfield model or on the Marini continuous fraction form. The models are tested in two ways. First awmming the “true” fium ray trace zenith value and compare the scaling of the delay at low elevations and then assuming a zenith delay prediction model and scale this value at low elevation. The first approachcan give us an “absolute” information about the accuracy of the model. Using the second approach we can get a better idea of what we can wait from models mainly for the wet delay prediction.
Published in:	Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999) June 27 - 30, 1999 Royal Sonesta Hotel Cambridge, MA
Pages:	403 - 417
Cite this article:	Ifadis, I.M., Savvaidis, P., "Review of Mapping Functions Proposed to Predict the Delay at Very Low Elevation Angles," Proceedings of the 55th Annual Meeting of The Institute of Navigation (1999), Cambridge, MA, June 1999, pp. 403-417.
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