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| Coordinates | Time Series | SCOUT | ||||||||||||
| SOPAC/CSRC Refined Coordinates Documentation |
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This utility provides xyz (ITRF2000 reference frame) and lat/lon/ht (WGS84 datum [CSRC users: NAD83 also]) coordinates for the reference epoch (day/year) selected. Select the site code(s) of interest using one of the two methods provided. Select the year, and enter the day-of-year. Choose filtered or unfiltered coordinates (see below for more information). Press the "Get Coordinates" button". The site code list may be restricted by selecting a site array.
These coordinates are generated using a model (Nikolaidis, 2002) that takes into account offsets (co-seismic or otherwise), linear velocity, and annual and semi-annual fluctuations (for stations that have at least two years and one year of data, respectively). For stations that experience post-seismic relaxation, an exponentially decaying term is also estimated. In some cases where a station experiences co-seismic and post-seismic deformation, changes in the linear velocity are also estimated. Input data provided to the model are the daily processed site positions calculated at SOPAC using the GAMIT and GLOBK software packages. Coordinates from the most recent SOPAC processing run are available. Coordinates are valid at the geodetic reference point (GRP). This point is x meters below the antenna reference point (ARP), where "x" is the antenna height recorded in the site log. All parameters are estimated with full white noise + flicker noise covariances based on a noise analysis of the GPS position time series. Their uncertainties can thus be considered realistic estimates, based on our data analysis. For sites in the western United States, filtered coordinates are available. This includes sites in the BARGN, BARD, EBRY, PANGA, and SCIGN permanent GPS networks, and western U.S. sites in the CORS network. The regional filtering is carried out in space domain. By stacking the time series from a group of core sites, a time series containing common noises for the region can be derived, which will then be subtracted from individual time series to improve positional estimates. Unfiltered time series are also available for these sites. For all other sites, only unfiltered time series are available. No regional filtering is performed for these sites. Note: for various reasons, not all sites archived at SOPAC are processed, and therefore many sites are not available via this utility. SOPAC attempts to process all western North America sites, and to include an adequate coverage of the rest of the globe. Many CORS sites in eastern North America are not processed, for example. Please contact the webmaster if you have any questions. |