information gathered from meetings, interviews with NGDC staff, and background material related to the committee’s review criteria (Appendix B). An analysis of these issues is given in Chapter 3.



NGDC holdings include seafloor and lakefloor analyses, descriptions, and sample inventories; trackline geophysical measurements; hydrographic sounding surveys; multibeam bathymetry tracks and surveys; sidescan sonar and multichannel seismic profiles; hazards information; ecosystems data and assessments; and solar, magnetospheric, ionospheric, geomagnetic, and cosmic ray data (Appendix C). Data are collected from a variety of platforms—ship, submarine, aircraft, ground and seafloor stations, and satellites. Satellite data held by NGDC include particles and fields, spacecraft anomalies, solar imagery, and solar radiation data from the National Oceanic and Atmospheric Administration’s (NOAA’s) geostationary and polar-orbiting satellites and the Air Force’s Defense Meteorological Satellite Program (DMSP). The DMSP holdings make up 97 percent of the total data volume at NGDC (Figure 2.1) and account for most of the growth in data volume at NGDC in the late 1990s (Figure 2.2). The archive will continue to grow at a rapid rate if NGDC acquires other large datasets currently under discussion (see “Data Acquisition and Transfer Strategy” below).

Although almost all of the newer datasets are in digital form, the center also maintains substantial holdings of paper, film, and microfilm records, as well as slide sets and posters (see Appendix C for a list of datasets). About 25 percent of the total volume of all NGDC data are online.2 Of the digital data holdings, 51 percent of solid earth geophysics (SEG) datasets, 62 percent of solar-terrestrial physics (STP) datasets, and 84 percent of marine geology and geophysics (MGG) datasets are online.3 In general, analog datasets are more difficult for staff to manage than digital datasets because the relevant metadata often do not reside with the analog records, which makes it harder to assemble useful datasets. Similarly, small, unique


Presentation to the committee by Michael Loughridge, director, National Geophysical Data Center, August 13, 2002.


Based on averages of the percent online of datasets for each division listed in Appendix A. Datasets vary in size, and the datasets given in Appendix A are highly aggregated, so these figures differ from the total amount of NGDC data online. Nevertheless, they provide an indication of where each division stands in making its data available online.

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