Stochastic estimation of tropospheric path delays in global positioning system geodetic measurements |
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Authors: | David M Tralli Stephen M Lichten |
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Institution: | (1) Jet Propulsion Laboratory, California Institute of Technology, 91109 Pasadena, CA, USA |
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Abstract: | Water vapor radiometric (WVR) and surface meteorological (SM) measurements taken during three Global Positioning System (GPS) geodetic experiments are used to calculate process noise levels for random walk and first-order Gauss-Markov temporal models
of tropospheric path delays. Entire wet and combined wet and dry zenith delays at each network site then are estimated simultaneously
with the geodetic parameters without prior calibration. The path delays and corresponding baseline estimates are compared
to those obtained with calibrated data and stochastic residual delays. In this manner, the marginal utility of a priori tropospheric
calibration is assessed given the ability to estimate the path delays directly using only theGPS data. Estimation of total zenith path delays with appropriate random walk or Gauss-Markov models yields baseline repeatabilities
of a few parts in 108. This level of geodetic precision, and accuracy as suggested by analyses on collocated baselines estimated independently
by very long baseline interferometry, is comparable to or better than that obtained after path delay calibration usingWVR and/orSM measurements. Results suggest thatGPS data alone have sufficient strength to resolve centimeter-level zenith path delay fluctuations over periods of a few minutes. |
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