Effect of wet tropospheric path delays on estimation of geodetic baselines in the Gulf of California using the Global Positioning System

Abstract

Geodetic baseline measurements using the Global Positioning System (GPS) were acquired in the Gulf of California between Loreto and Cabo San Lucas in Baja California and Mazatlan on the mainland of Mexico. Tropospheric water vapor content was high during the experiment, typically yielding wet path delays in excess of 20 cm at zenith. Surface meteorological (SM) and water vapor radiometer (WVR) measurements were recorded at each site, providing independent means of calibrating the GPS signal for the wet tropospheric path delay. Residual wet delays at zenith are estimated as constants and also as first‐order exponentially correlated stochastic processes. In addition, the entire wet zenith delay is estimated stochastically without prior calibration. The results of these approaches are compared in terms of day‐to‐day baseline repeatability and other system performance discriminants. Calibration with WVR data yields the best repeatabilities, of the order of 1–7.5 parts in 108 in the horizontal components of 350‐ to 650‐km baselines with carrier phase data. Further improvement in these results occurs if combined carrier phase and pseudorange data are used. WVR data are important for direct characterization of the wet tropospheric path delays in humid regions. SM measurements, if used with a simple atmospheric model and estimation of residual zenith delays as constants, can introduce significant errors in baseline solutions. However, SM calibration and stochastic estimation of residual zenith wet delays may be adequate for precise estimation of GPS baselines, with a deterioration in repeatability of less than 1–2 cm compared to WVR calibration. Stochastic estimation of the entire zenith wet delay yields comparable repeatabilities, particularly if both carrier phase and pseudorange data are used. Similar analyses of the Owens Valley Radio Observatory‐Mojave baseline in California, where zenith wet delays are factors of 3–5 less, show no significant differences among the various tropospheric calibrations.

Determination of vertical displacements over the coastal area of Korea due to the ocean tide loading using GPS observations

“…At JPL, GIPSY/OASIS-II has been used extensively during the last decade to analyze GPS carrier-phase and pseudo-range data from many experiments, yielding baseline precisions on the level of 10 −9 or less (Lichten and Border, 1987;Tralli et al, 1988). The data processing started with automatic editing of the GPS data.…”

GPS and Space-Based Geodetic Methods

“…By the mid 1980s, commercial receivers such as the Texas Instrument TI 4100 became available (Henson et al, 1985) and were quickly deployed by geophysicists in several pioneering experiments to measure the slow motions associated with plate tectonics (Dixon et al, 1985;Freymueller and Kellogg, 1990;Prescott et al, 1989); such experiments spurred the development of analysis techniques to improve precision at the level required by geophysics Tralli et al, 1988). Important developments during these early years include ambiguity resolution over long distances (Blewitt, 1989;Dong and Bock, 1989), precise orbit determination King et al, 1984;Lichten and Border, 1987;Swift, 1985), and troposphere modeling (Davis et al, 1987;Lichten and Border, 1987;Tralli and Lichten, 1990).…”

A New Window-Based Program for Quality Control of GPS Sensing Data

“…To achieve this, we calculated the quality control indicators using 5 days of GPS observations, from September 1 to 5, 2009 at Suwon station (SUWN), which were registered with the International GNSS Service (IGS). Data processing was carried out by the Precise Point Positioning (PPP) technique from GIPYS/OASIS-II software, which was developed in the Jet Propulsion Laboratory (JPL) and is capable of calculating to a level of processing equivalent to a few millimeters in GPS data processing [21,22]. Table 3 lists the results of quality control indicators (%) and the precision (significance level of ±1σ) of post processing.…”