The Scripps Orbit and Permanent Array Center (SOPAC) has been archiving and analyzing global and regional continuous GPS data since 1990. By November 1991, SOPAC began estimating precise GPS satellite ephemerides within 5-7 days of data collection to support high accuracy crustal deformation measurements by regional continuous GPS arrays. By June 1992, several other groups had also begun computing precise satellite ephemerides as a pilot project for the new International GPS Service for Geodynamics (IGS).
SOPAC maintains one of the three Global Data Centers for the IGS (the other two are NASA/Goddard Space Flight Center and Institut Géographique National, Paris). Continuous data from over 100 IGS sites are collected, quality-controlled, and archived. In addition, SOPAC is one of eight Analysis Centers, computing precise, rapid, and predicted orbits, Earth orientation, and weekly SINEX global solution files for the IGS. Furthermore, the SOPAC Director is an active member of the IGS Governing Board.
To access the SOPAC data archive:
SOPAC is the primary data archive of continuous GPS data collected by the Southern California Integrated GPS Network (SCIGN). Data from 50 continuous GPS sites are currently archived. The array is in the process of being expanded to 250 stations. SOPAC also archives data from the 13 stations of the Bay Area Regional Deformation (BARD) array in northern California. SOPAC archives nearly 90 sites of the U.S. Continuously Operating Reference Station (CORS) network data in part to support a project funded by NOAA to develop and maintain a near real-time water vapor monitoring system. In addition, SOPAC is one of two analysis centers for SCIGN (the other is JPL), and is responsible for downloading and maintaining about 20% of the network (USGS Pasadena is responsible for the other 80%).
The Institute of Geophysics and Planetary Physics (IGPP) at SIO maintains a geophysical mass storage facility which presently includes optical, magnetic, and tape storage robots. The bulk of the mass store is a magnetic tape system manufactured by Metrum. The medium itself is a 2150 tape, physically identical to VHS tapes used for video recording. The capacity of this tape system is presently 2 TBytes. We have been funded by NSF to upgrade the system to in excess of 7 TBytes within the next 6 months. In addition, the system includes nearly a TB of 5 1/4" rewriteable optical storage (HP) which is, in turn, fronted by 50 GB of magnetic RAID storage. Presently stored are a variety of geophysical data including multichannel seismic, global seismic, seismic array, GPS, and Geosat data. Recently a 600FX HP Magneto Optical Jukebox has been added (see next section).
The following hardware/software have been purchased (since May 1996) or will shortly be on order (*) to support archiving activities at SOPAC. The first item was partly funded by the NSF UNAVCO grant. All other items were funded through the SCIGN project but are of benefit to UNAVCO users.
The Scripps Orbit and Permanent Array Center is currently developing a RDBMS that will contain information related to continuous GPS arrays, ranging from raw data to data products. The UNAVCO Boulder Facility has already developed a RDBMS that contains metadata describing GPS sites and data collected by them. The two databases, though somewhat different in applications, share common data. A seamless integration of these RDBMS's is being developed to provide users easy access to more data.
The two archives have different approaches to storing data and relational database design, this however does not prove problematic to the implementation of a seamless archive. With current database technology and quality user interfaces there is no need to "mirror" the database systems. To allow the two archives independence, UNAVCO and SOPAC are jointly developing a "core" schema that will be used to create queries to be remotely executed at participating archives. At present the exact schema and its identifying features are being decided on. Once the schema have been developed, its implementation is relatively simple. In the event of a design change it can be altered dynamically.
With the core schema developed and database populated, the implementation of a first generation user interface to access the data will begin. The interface specifications and design are already being discussed by SOPAC and UNAVCO. This interface will remove the need for a user to direct their queries to a particular archive. This interface will allow the user to collect information and data without having to know the exact source of the data (unless requested). The implementation of the user interface will be using HTML Forms and a server side CGI interface which will then access the database. Second generation interfaces may include three tier client server architecture using JAVA, IDL (Interface Definition Language), CORBA (Common Object Request Broker Architecture), and IIOP (Internet Inter Orb Protocol) which will better allow users to access, control access, and query data. These developing technologies will allow greater portability and dynamic development. With these new technologies, the "core" schema can be extended to other, non-Oracle, databases with relative ease.
Last modified: Monday, 27-Oct-2014 18:36:09 UTC