Arctic Gravity Project - New!Updated Data Sets



Public domain gravity grids derived from airborne, surface and submarine data in the Arctic from a multitude of sources. Data have been prepared by a working group under the International Gravity and Geoid Commission, International Association of Geodesy.


Below are the newest data sets, updated on March 19, 2008. For historical data sets, including Elevation and Geoid data, visit the historical data page.

1.) Data File: (Click on filename to download)
ArcGP_GRV - 5' x 5' data file, 0 - 360 longitude, Free-air anomalies, WGS 84, with atmospheric correction
 
2.) Plots: (Click on plot for full size view)
5'x5' free-air gravity anomalies
Source Codes


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Format of files: All grids are in GRAVSOFT (scanline) format.
Data are stored in E-W rows from N to S. 
The header (latS,latN,lonW,lonE,dlat,dlon) defines limits in degrees.
The first point in file is thus (latN,lonW), last value (latS, lonE).
Main ArcGP grids contain:
312 rows and 4320 columns (5'x5') or 
312 rows and 2160 columns (5'x10')

*Remember:  If you change platforms (Windows/Unix) between the download and 
the running of the data, check for extra characters (i.e. ^M).


Generic Fortran code to read grids:
dimension row(4320)
read(*,*) rlat1,rlat2,rlon1,rlon2,dlat,dlon
nn = (rlat2-rlat1)/dlat+1.5
ne = (rlon2-rlon1)/dlon+1.5
rlat = rlat2
do i = 1, nn
  read(*,*) (row(j),j=1,ne)
  rlon = rlon1
  do j = 1,ne
    if (rlon .gt. 360) rlon = rlon1
    write(*,*) rlat, rlon, row(j)
    rlon = rlon + dlon
  enddo
  rlat = rlat - dlat
enddo

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Point of Contact: Office of Geomatics
phone (314) 676-9127, DSN 846-9127
wgs84@nga.mil

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