The primary scientific application of high-precision geodetic observations is to measure crustal deformation and motion caused by geodynamic processes. These measurements can only be made by comparing two or more sets of observations separated by a time span of minutes, years, or decades. For this reason, GPS data preservation is essential. The scientific value of high-precision geodetic data depends not only on the quality of the data, but also on the accuracy and reliability of the associated information about the data, including the location where the data were taken, the equipment used, and the geometry of the equipment setup relative to a recoverable mark. Verifying and preserving this ancillary metadata is just as essential as preserving the data itself.

The Data Management and Archiving Group operates the Boulder Facility Archive, which provides long-term secure storage and easy retrieval of GPS data as well as metadata. The Archive primarily stores high-precision geodetic data used for research purposes, collected under National Science Foundation and NASA sponsored projects.

The Boulder Facility Archive has three main components: the Physical Repository, the On-line Repository, and the Archive Database. The Physical Repository is a set of storage rooms employing a specially-designed filing system for locating the one or more archive boxes for each project. The project archive boxes hold data on any original field media or investigator supplied media (e.g. floppy disk, optical disk, tape), a mass storage copy of these data, log sheets, maps, photos, site descriptions and notes, correspondence, and other physical material associated with the data for the project. There are over 700 catalogued boxes of archive material in the Physical Repository.

The On-line Repository consists of a hierachical file system on a set of RAID hard disks with LTO tape jukebox backup. The file system stores all data files that have been and verified and ingested. The same file system is used to store ancillary digital information such as logsheet image files and project documentation in digital format. The On-line Repository holds 1.5 million files.

The Archive's database (Oracle RDBMS) contains an index to files in the On-line Repository, and metadata pertaining to details about projects, funding, principal investigators, sites, monuments, visits, etc. The Archive database greatly simplifies data research by providing the community with access to information about site locations, previous site occupations, all occupations of a given site or set of sites, data groupings such as Campaigns or Permanent Station Networks, and more.

Corresponding to the two typical modes of data collection, campaign mode (also known as episodic or survey mode) and permanent station mode (also known as continuous), the data in the Archive is categorized as Permanent Station or Campaign. The Facility's Permanent Station data holdings are all available in RINEX and Hatanaka compressed format in an anonymous FTP pickup area. (Please see FTP Server Layout for information on navigation of UNAVCO's FTP directory structure.) Under an automated data handling mechanism, these public files appear in the FTP pickup area within minutes of their arrival and archiving at the Facility. Searches for single or multiple permanent stations by name, temporal data availability, spatial, and other criteria can be accomplished with the Permanent Station search tool.

Users of Campaign data generally need access to an entire campaign, or to a series of campaigns taking place over several years. Campaign data has some access restrictions (see the data policy). A two-year grace period, during which only the Principal Investigator has access to the data, applies to most campaigns. Most campaigns deposited prior to July, 2003 are available by request only, due to the conditions of an earlier data policy. Most campaigns deposited after July 2003 become anonymously available after their two-year grace period expires. Searches for single or multiple campaigns by name, region, time period, and other criteria can be accomplished with the Campaign search tool. Once campaigns of interest are identified, anonymous data access or access by request is facilitated by following the "Data Availability" links.

Comments or questions about this page? Please e-mail the Archive Staff (archiveunavco.org).

Last modified Monday, 17-Dec-2007 15:54:40 MST

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