GEODAS Data Formats - MGD-2000

The National Geophysical Data Center (NGDC) has developed a series of data formats for various purposes. Among these are several formats for the exchange, storage and dissemination of marine geophysical data. These "MGD-2000" formats are used extensively by the GEODAS software as well as other software applications.

MGD77 - The data in the Marine Trackline Geophysics Database is in the MGD77 Format. This is an ASCII exchange format for marine geophysical data. Each formatted survey unit contains all observations that conveniently constitute a data subset (e.g. a port-to-port survey) and consists of both a Header file to document survey information and a data record file in time series containing fields for date, time, bathymetry, magnetics, gravity and seismic navigation.

HYD93 - The data in the Hydrographic Surveys Database is in the HYD93 Format. This is an ASCII exchange format for hydrographic data. Each HYD93 formatted survey represents all observations that conveniently constitute a data subset (generally a specific area targeted for mapping, with one or more port-to-port operations). Each survey consists of both a Header file to document survey information and a data record file in time series containing fields for Survey-Id, latitude, longitude, depth, depth-type and cartographic code.

ARO88 - The ARO88 Header Format This is an ASCII exchange format for meta-data (documentation) for Aeromagnetic survey data. This format contains fields such as dates, instrumentation, reference fields used, flight data and the format for the data records, which come in a multitude of formats.

GRD98 - The GRD98 Format This is a digital format for the storage of gridded data. Though developed for bathymetric/topographic data, the format can handle virtually any type of gridded data. It is very utilitarian format and contains no documentation about the grids (such as information about references, methods and datums used, etc.). Rather GRD98 formatted files only contain grid- structure information followed by the grid cell data values.

VCT00 - The VCT00 Format This is a digital format for the storage of 2-D vector data. Though developed for high resolution boundary (coastline) data, the format can handle other types of vector data such as contours. It is very utilitarian format and contains no documentation about the data (such as information about references, methods and datums used, etc.). Rather VCT00 formatted files only contain vector data records and headers with minimal geographic and file- indexing information.

XYZ03 - The XYZ03 Format This is a digital format for the storage of xyz (longitude, latitude, value) geospacial potential field data. It is very efficient format in that it is binary integers and the record size (12 bytes) is small and yet contains latitude, longitude and value precision sufficient for most users. The format contains no headers and thus no documentation about the data (such as information about references, methods and datums used, etc).