Date: Tue, 13 Aug 2002 12:40:32 -0400 (EDT) From: Carey Noll To: igs-dcwg@igscb.jpl.nasa.gov Subject: [IGS-DCWG-2] IGS Data Center Working Group and GSAC Message-ID: Sender: owner-igs-dcwg Precedence: bulk ****************************************************************************** IGS-DCWG Mail 13 Aug 10:14:09 PDT 2002 Message Number 2 ****************************************************************************** Author: Carey Noll Dear Colleagues, It has been several weeks since my last message, introducing the new working group mailer Angie set up at the IGS CB, as well as asking for thoughts on how to start some of our activities. Unfortunately, I did not hear from anyone yet, much to my chagrin (I realize the summer is of course a time of vacations). Regardless, I would like to draw your attention to some recent developments with the GSAC, the GPS Seamless Archive Center activity. You may recall Micheal Scharber gave a presentation at the IGS workshop in April on GSAC. The GSAC working group recently held a meeting in Boulder (see the minutes at http://www.unavco.ucar.edu/data_support/data/gsac/gsac_meeting_boulder-jul02.html to review progress and make plans for future development. At this time the working group would very much like to encourage participation in GSAC by other GPS archives, particularly outside the U.S. To that end, I would encourage you to check out the GSAC web page and supporting documents at http://gsac.ucsd.edu, the standards documentation at http://www.unavco.ucar.edu/data_support/data/gsac/GSAC-1.1.html. You can test the Retailer client through these web sites. The web version provides a useful search tool but has less flexibility and cannot actually retrieve data. To use the command-line client, you can download one of the executables through http://gsac.ucsd.edu/downloads.html. Bob King and Michael Scharber note that there are two important limitations of the current Retailer: 1) The database queries are not yet efficient enough to do a spatial (bounding box) search over a time span of more than a month. 2) There is no mechanism to separate file listings for continuous and non-continuous stations, so the return stream for any search spanning more than a few days will be very long and dominated by the listings for continuous stations. SOPAC is addressing both of these problems. In the meantime, a reasonable approach is to do spatial search on the Monument Catalog only, and then then a time-span search on selected sites. The GSAC listings are essentially complete for western North America, so an instructive direct search (spatail plus time), might be gsac-client -f info -v -sy 1992 -sd 001 -ey 1992 -ed 180 -t rinex_obs -bb 240,34,241,35 or the equivalent inquiry via the web page. This query should execute in less than 30 seconds. Please correspond with Michael Scharber (mscharber@josh.ucsd.edu) with any feedback or questions on the client. At this time, the CDDIS is serving as a GSAC Wholesaler; it did not take us a great deal of effort to implement s/w to create the appropriate supporting files required by the GSAC infrastructure. I would encourage all IGS data centers to consider making the metadata from their archives accessible through the GSAC. I am also hoping to hear from the members of our group as to your thoughts on a user survey and documenting the data flow of the IGS network. Regards, Carey. +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+ Ms. Carey Noll Manager, Crustal Dynamics Data Information System (CDDIS) Secretary, ILRS Central Bureau Code 920.1 E-mail: noll@cddisa.gsfc.nasa.gov NASA GSFC Voice: (301) 614-6542 Greenbelt, MD 20771 Fax: (301) 614-5970 USA WWW: http://cddisa.gsfc.nasa.gov/cddis_welcome.html +=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+=+