GEODAS (GEOphysical DAta System) is a Year 2000 compliant, interactive database management system
developed by the National Geophysical Data Center (NGDC) for use in the
assimilation, storage and retrieval of geophysical data. The GEODAS software can handle multiple
databases of several types of data. GEODAS is presently being used with:
Marine Trackline Geophysical Data
Hydrographic (bathymetric) Data
GEODAS Gridded Databases
Aeromagnetic Survey Data
Searches by geographic area, year of survey, source, platform/project, survey identifier, or data type are available.
GEODAS includes both a data management sofware (including assimilation and quality control) and user access software, which accompanies GEODAS CD/DVD sets.GEODAS works with a series of formats described as Marine Geophysical Data 2000 (MGD-2000). Marine Trackline Geophysics, Hydrographic Surveys and Aeromagnetic Surveys are comprised of one Header record and multiple Data records. The Header record documents both the content and the structure of the subsequent Data records, containing that part of the data that remains invariant throughout the survey. The Data records present geophysical data with corresponding times and positions. Documentation that varies within the survey is also included with the data records. GEODAS Gridded Databases contain a Header Record describing the grid parameters, followed by the grid cell values
You can perform on-line Searches and FTP transfers using GEODAS on the Internet, and complete MS Windows and UNIX XWINDOWS version of GEODAS are available.
Additional information may be found via the world wide web (www.ngdc.noaa.gov/mgg/geodas/geodas.html), anonymous ftp (ftp.ngdc.noaa.gov) and gopher. For pricing and order information or technical assistance contact NGDC.
The data on the GEODAS CD/DVD data sets are of the best quality NGDC can obtain. Most have gone through extensive processing at their place of origin. The Headers that are available on this disc provide information on the accuracy of the data. NGDC makes no warranty as to the correctness of data values on these discs, but they are representative of the data as of their transfer to NGDC.
NGDC is building its global marine data bases to better serve as the international focal point for marine geological and geophysical data management. NGDC is pleased to accept contributions of geophysical data on almost any media, preferably in the MGD77 or HYD93 Exchange Formats. A format of the contributor's choice is also acceptable provided that it is well documented. Any data received is in the international public domain, readily available globally to any interested individual or group.
NGDC's Hydrographic Survey Database includes surveys by the U.S. National Ocean Service, providing the most accurate and extensive digital bathymetric data available for the coastal waters of the continental United States, Alaska, Hawaii and Puerto Rico/Virgin Islands. Because the database contains all depth values obtained during the surveys, more detailed bathymetric information is available than can normally be found on published nautical charts compiled from the same surveys. The dense inshore and shallow-water data are well suited for computer generation of grids to be used in hydrodynamic models of estuaries and other coastal systems. The data provided are an historical data set, and as such they may not always reflect current conditions. Thus the data are NOT TO BE USED FOR NAVIGATION PURPOSES. For navigation uses, please refer to the NOS Nautical Chart Series. These can be obtained at various chart vendors or by contacting: Customer Services, N/CG333, NOAA, National Ocean Service, 6501 Lafayette Ave., Riverdale, MD 20737-1199.
NGDC's Hydrographic Survey Data is organized by survey and stored in the HYD93 exchange format as described in the file hyd93.txt. Each ASCII header file contains 24 80-character records, each containing specific fields. Each ASCII data file contains a series of 37-character Data records for a particular survey operation For more information on obtaining these data, please contact NGDC.
NGDC's Coastal Relief Project involves gridding the bathymetric data from the NOS Hydrographic Surveys and, after combining this with US land topography grids, creating a series of 1 degree grids at a 3 arc-second resolution in US coastal areas. This data is available on GEODAS CD/DVD sets with software for combining, translating and sub-sampling grids for users.
The Great Lakes Bathymetry Project produces grids, contours and images of the Great Lakes. CD/DVDs with access software for each of the lakes is being produced, using bathymetric data from the NOS Hydrographic Surveys and contour data from various sources.
ETOPO2 is a gridded database of bathymetry and land topography covering the entire surface of the earth. Grid cell spacing is 2 arc-minutes. The grids on the GEODAS ETOPO2 CD/DVD set are in the GEODAS Gridded Data Format - GRD98. The GEODAS Software can be used to create custom grids.
The Marine Trackline Geophysical Database contains bathymetric, magnetic, gravity and digital shot-point navigation data collected during marine surveys from 1953 to the present. Coverage is worldwide and new data are continually being added. Data sources include both U.S. and foreign oceanographic organizations. NGDC's digital marine trackline geophysical data holdings have been released as a CD/DVD data set by NGDC's Marine Geology and Geophysics Division, complete with PC-compatible search and retrieval software for DOS and Microsoft Windows as well as UNIX compatible X-Windows. Data are stored in the MGD77 exchange format as described in the file mgd77.txt. Each ASCII header file contains 24 80-character records, each containing specific fields. Each ASCII data file contains a series of 120-character data records for a particular cruise/leg (port to port operation).
NGDC's Aeromagnetic Survey Database is searchable with the GEODAS software. The aeromagnetic data records are not available directly using the GEODAS. Each ASCII header file contains 24 80-character records, each containing survey documentation in specific fields The ARO88 Headers are described in file aro88.txt. The data records are not in a common format, rather they have retained the format in which they were submitted to NGDC. For more information on obtaining these data, please contact NGDC.