NGDC Number

A unique 8-character identifier assigned by NGDC to each survey in the database.

The scheme for numbering is as follows:

For Marine Trackline, Hydrographic Survey and Aeormagnetic Data:

The first 2 characters identify the source (for MGD77 or HYD93)

The first 4 characters identify the platform (or project for ARO88)

The last 4 digits are assigned consecutively

For GEODAS Gridded Database Grids:

CD sets contain a series of grids covering the area of the GEODAS Gridded Database. These CD/DVD grids are blocks of n X n degrees with the following naming convention:

The first 2 characters identify the project (gn=Coastal Relief Model or Great Lakes Bathymetry, ge=ETOPO2 Gridded Elevation Data)

The 3rd character identifies the quadrant, relative to (0,0):

a = NorthWest

b = NorthEast

c = SouthEast

d = SouthWest

The 4th thru 5th characters identify the upper latitude limit (00 to 90)

The 6th thru 8th characters identify the leftmost longitude limit (000 to 180)