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The semidiurnal variation in GPS‐derived zenith neutral delay
Author(s) -
Humphreys T. E.,
Kelley M. C.,
Huber N.,
Kintner P. M.
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2005gl024207
Subject(s) - zenith , variation (astronomy) , geodesy , global positioning system , amplitude , solar zenith angle , harmonics , geology , atmospheric sciences , environmental science , physics , astrophysics , optics , quantum mechanics , voltage , computer science , telecommunications
Zenith neutral delay (ZND) estimates derived from ground‐based GPS receivers exhibit variations at harmonics of the solar day. The aim of this work is to characterize the semidiurnal ( S 2 ) variation and determine its probable origin. Data from 100 GPS sites are compared with surface pressure measurements to reveal close agreement between the estimated ZND S 2 variation and the S 2 surface pressure tide. Error analysis suggests that the S 2 variation in ZND estimates is not due primarily to orbit, solid earth, or Earth orientation modeling errors. Atmospheric loading and mapping function errors are each expected to contribute less than 11% to the estimated ZND S 2 amplitude. Local incongruities reflect the influence of water vapor or site‐dependent errors.