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The Effect of Seasonal and Long-Period Geopotential Variations on the GPS OrbitsWe examine the impact of using seasonal and long-period time-variable gravity field (TVG) models on GPS orbit determination, through simulations from 1994 to 2012. The models of time-variable gravity that we test include the GRGS release RL02 GRACE-derived 10-day gravity field models up to degree and order 20 (grgs20x20), a 4 x 4 series of weekly coefficients using GGM03S as a base derived from SLR and DORIS tracking to 11 satellites (tvg4x4), and a harmonic fit to the above 4 x 4 SLR-DORIS time series (goco2s_fit2). These detailed models are compared to GPS orbit simulations using a reference model (stdtvg) based on the International Earth Rotation Service (IERS) and International GNSS Service (IGS) repro1 standards. We find that the new TVG modeling produces significant along, cross-track orbit differences as well as annual, semi-annual, draconitic and long-period effects in the Helmert translation parameters (Tx, Ty, Tz) of the GPS orbits with magnitudes of several mm. We show that the simplistic TVG modeling approach used by all of the IGS Analysis Centers, which is based on the models provided by the IERS standards, becomes progressively less adequate following 2006 when compared to the seasonal and long-period TVG models.
Document ID
20160013891
Document Type
Reprint (Version printed in journal)
Authors
Melachroinos, Stavros A. (SGT, Inc. Greenbelt, MD, United States)
Lemoine, Frank G. (NASA Goddard Space Flight Center Greenbelt, MD United States)
Chinn, Douglas S. (SGT, Inc. Greenbelt, MD, United States)
Zelensky, Nikita P. (SGT, Inc. Greenbelt, MD, United States)
Nicholas, Joseph B. (Emergent Space Technologies, Inc. Greenbelt, MD, United States)
Beckley, Brian D. (SGT, Inc. Greenbelt, MD, United States)
Date Acquired
November 30, 2016
Publication Date
November 27, 2013
Publication Information
Publication: GPS Solutions
Volume: 18
Issue: 4
Subject Category
Communications and Radar
Report/Patent Number
GSFC-E-DAA-TN21221
Funding Number(s)
CONTRACT_GRANT: NNG11HP14C
Distribution Limits
Public
Copyright
Other
Keywords
Orbit determination
Time-varying gravity
GPS