HR: 08:20h
AN: G21B-02 INVITED     [Abstracts]
TI: Spatial and temporal filtering for high-rate GPS regional networks: Implications for reference frame definition
AU: * Bock, Y
EM: ybock@ucsd.edu
AF: Scripps Institution of Oceanography, IGPP 0225 9500 Gilman Drive, La Jolla, CA 92037 United States
AB: GPS data from regional networks such as those established in the Western U.S. over the last decade (BARD, BARGEN, EBRY, PANGA, SCIGN) are routinely processed with respect to ITRF in 24-hour segments, based on 30 s sampled data (often decimated to even lower rates). (The Plate Boundary Observatory's strategy appears to be the same, although data will be collected routinely at a 15 s sampling rate.) The result is a time series of daily site positions, which are spatially filtered to remove a common mode signal. This spatial filtering process is performed simultaneously with a parameter fit to the time series that includes rates (velocities), offsets (coseismic and/or instrumental), seasonal terms (annual and semiannual), and perhaps postseismic terms (exponential or logarithmic). There are several variations to this approach, as well as several complications, such as when the network in question becomes larger. Nevertheless, the spatial filtering results in a significant reduction in the rms for the resulting daily position time series, about 1 mm in the horizontal components, and 3-4 mm in the vertical. There is an ongoing effort in southern California to upgrade SCIGN stations to high-rate sampling (1 Hz or higher), and real-time ($<$1 s latency) streaming and instantaneous positioning. More than 50 stations have already been completed. I demonstrate with upgraded SCIGN stations that routine instantaneous positioning of ultra-high-rate data (10-20 Hz) is possible and provides several advantages over the traditional approach mentioned above that can be exploited to increase the sensitivity of CGPS data for the detection of transient deformation over a range of temporal scales. (One of the primary goals of the PBO project is to observe and quantify transient deformation.) In this paper I discuss ways to maintain a consistent regional reference frame for this observational/analysis approach that takes into account various scientific and civil objectives.
DE: 7205 Continental crust (1242)
DE: 1229 Reference systems
DE: 1242 Seismic deformations (7205)
DE: 1243 Space geodetic surveys
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting