CAUTION: This data set was corrected and updated in 2006 -
Please use the newer, corrected version.

ETOPO2 Global 2-Minute Gridded Elevation Data 
version 2001

Data: Land Elevations and Ocean Bathymetry

Raw 2-minute grids in:

        1.  big-endian (ETOPO2.raw.bin) & 
        2.  little-endian (ETOPO2.dos.bin)

formats (16-bit signed integers, 10800 columns x 5400 rows)

For full information about ETOPO2, including searching, extraction,
display capabilities, please see

  http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html

The full GEODAS custom grid functionality is now online:
You can now produce and download custom grids from ETOPO2 on-line
for free: 

  http://www.ngdc.noaa.gov/mgg/gdas/gd_designagrid.html
 
warning: you do not need to download the full database, just run
         designagrid on-line.


Frequently Asked Questions:

    * What are the datums (horizontal and vertical references) for ETOPO2?

      The horizontal datum is WGS-84, the vertical datum is Mean Sea Level.

    * How does one cite ETOPO2?

      U.S. Department of Commerce, National Oceanic and Atmospheric
      Administration, National Geophysical Data Center, 2001. 2-minute Gridded
      Global Relief Data (ETOPO2) 
      http://www.ngdc.noaa.gov/mgg/fliers/01mgg04.html

    * What is the resolution of ETOPO2?

      The horizontal resolution is 2-minutes of latitude and longitude (1.853
      km at the Equator). The vertical resolution is 1 meter.

    * What is the projection of ETOPO2?

      ETOPO2 is in the Cylindrical Equidistant Projection (sometimes called
      Latitude-Longitude, or Geographic).

    * What do the grid data actually represent?

      The grid values represent the elevation at the grid intersections at
      even multiples of 2 minutes of latitude and longitude, averaged over the
      cell's area.

    * Is the sea floor really that bumpy, and what are the long, straight
      lines on the ocean floor that converge on places like San Diego and
      Bermuda?

      The "orange-peel" look of the sea floor is mostly an artifact of the
satellite altimetry technology and its interpretation of ocean surface waves.
The straight lines are where direct shipborne measurements have been included
in the data as "ground truth". These measurements help calibrate, but do not
correspond 100 percent to the radar altimetry. See W.H.F. Smith and D.T.
Sandwell, 1997, Global Sea Floor Topography from Satellite Altimetry and Ship
Depth Soundings, Science 277 (5334), p.1956-1962.

    * What about shallow (<200m) water?

      The satellite altimetry works best in deep water and can distinguish
many undersea features that are not otherwise surveyed directly. In shallow
water, the gravitational effects that can be measured from the satellite are
too small to be reliable. In US waters and some other areas, local
high-resolution survey data have been used where available.

    * How do I run ETOPO2?

      ETOPO2 is a database, not a program. You will need imaging or analysis
      software to use the data.


revised Wed Jul 13 2005 13:05:23 GMT-0600 (Mountain Daylight Time) W3C