Improving the precision of high‐rate GPS

Abstract

[1] In order to improve the accuracy of high-rate (1 Hz) displacements for geophysical applications such as seismology it is important to reduce systematic errors at seismic frequencies. One such GPS error source that overlaps with seismic frequencies and is not currently modeled is multipath. This study investigates the frequencies and repetition of multipath in high-rate GPS time series in order to maximize the effectiveness of techniques relying upon the geometric repeatability of GPS satellite orbits. The implementation of the aspect repeat time adjustment (ARTA) method described here uses GPS position time series to estimate time-varying and site-dependent shifts. As demonstrated for high-rate GPS sites in southern California this technique significantly reduces positioning noise at periods from 20 to 1000 s. For a 12-hour time series, ARTA methods improve the standard deviation of the north component from 8.2 to 5.1 mm and the east component from 6.3 to 4.0 mm. After applying ARTA corrections, common mode errors are removed by stacking. This method further improves the standard deviations to 3.0 and 2.6 mm for the north and east components, respectively.

Observation of Core Phase ScS from the Mw 9.0 Tohoku-Oki Earthquake with High-Rate GPS

“…3a). For station HLHG in northeastern China, the amplitude of ScS is about 6.2 mm and is a little bit above the 4-5 mm resolution of horizontal displacement resolved from high-rate GPS without stacking (Larson et al, 2007). Though clipped at strong ground motion, broadband seismometers are sensitive for small ground displacements.…”

“…We mitigate multipath errors in the high-rate GPS displacement time series by applying Aspect Repeat Time Adjustment (ARTA). We use two extra days of data (DOY 68-69, 2011) for each station following methods by Larson et al (2007).…”

Strain Rates in the Sichuan-Yunnan Region Based upon the Total Least Squares Heterogeneous Strain Model from GPS Data

“…2, 133-147, April 2011 20 mm for 1992 (Freymueller et al 2008). Segall and Davis (1997) thought that individual GPS measurements across regional scales had accuracies of 2 -5 mm for horizontal components and were a factor of 3 worse for vertical components; Dietrich et al (2001) obtained a combined solution with an accuracy of 1 cm for the horizontal plane and 2 cm for the vertical coordinate components within ITRF96; Larson et al (2007) improved the standard deviations to 3.0 and 2.6 mm for the north and east components of the high-rate GPS, respectively. Although the errors of GPS site coordinates are not very large, they can have a real impact on the estimations of strain rate.…”

Using Filtered and Semicontinuous High Rate GPS for Monitoring Deformations

“…Several recent investigations (Choi et al 2004;Larson et al 2007;Agnew and Larson 2007;Ragheb et al 2007a) have shown that the actual satellite geometry repeat interval ("sidereal lag") is slightly less than the nominal sidereal period used in earlier sidereal filtering studies, and that it varies at the few-second level across the constellation.…”