ETOPO2 - 2 minute Worldwide Bathymetry/Topography

Data taken from National Geophysical Data Center(NGDC) CD-ROM, ETOPO2 
Global 2' Elevations, September 2001.  


Author

     Dr. Peter W. Sloss (Peter.W.Sloss@noaa.gov), 
     NOAA/NGDC
     Mail Code E/GC3, 325 Broadway, Boulder, CO USA 80305
     303-497-6119, fax 303-497-6513
     

A Cylindrical Equidistant projection was used, which spans 360 degrees
of of longitude from 180 West eastward to 180 East; latitude coverage is
from 90 degrees North to 90 degrees South.  

Major Sources of Data :

  1. The seafloor data between latitudes 64— North and 72— South are
     from the work of Smith and Sandwell (1997). These data were derived
     from satellite altimetry observations combined with carefully,
     quality-assured shipboard echo-sounding measurements, by Dr. Walter
     H.F. Smith, of the NOAA Laboratory for Satellite Altimetry and Dr.
     David T. Sandwell, of the Institute of Geophysics and Planetary
     Physics at the University of California, San Diego. Data version
     8.2 is used here.

     For reference on generation of these data, consult: W.H.F. Smith
     and D.T. Sandwell, "Global Sea Floor Topography from Satellite
     Altimetry and Ship Depth Soundings," Science Magazine, vol. 277,
     issue 5334, 1997.

  2. Seafloor data southward of 72— South are from the US Naval
     Oceanographic Office's (NAVOCEANO) Digital Bathymetric Data Base
     Variable Resolution (DBDBV), version 4.1, gridded at 5 minute
     spacing; some data in this region are from the older DBDB5 (these
     data were also used in ETOPO5). Seafloor data northward from 64—
     North are from the new International Bathymetric Chart of the
     Arctic Ocean (IBCAO) Version 1.

     For reference on generation of the IBCAO data, consult:
     Jakobsson,M., N.Z. Cherkis, J. Woodward, R.Macnab, and B. Coakley.
     New grid of Arctic bathymetry aids scientists and mapmakers;
     Eos,Transactions, American Geophysical Union, v.81, no.9, p.
     89,93,96.

     For more information about IBCAO see:
     www.ngdc.noaa.gov/mgg/bathymetry/arctic/arctic.html 
     
     For more information about DBDBV see, file 'dbdbvnfo'   

  3. Land topography is from the GLOBE Project, an internationally
     designed, developed, and independently peer-reviewed global digital
     elevation model (DEM), at a latitude-longitude grid spacing of 30
     arc-seconds (30"). The GLOBE Task Team was established by the
     Committee on Earth Observation Satellites (CEOS). It is part of
     Focus I of the International Geosphere-Biosphere Programme - Data
     and Information System. Primary contributors to the GLOBE database
     are:

        o National Imagery and Mapping Agency (formerly Defense Mapping
          Agency), Fairfax, Virginia, USA
        o Geographical Survey Institute, Tsukuba, Japan
        o Australian Surveying and Land Information Group, Canberra, ACT,
          Australia
        o Jet Propulsion Laboratory, Pasadena, California, USA
        o University College London, UK
        o DLR-German Remote Sensing Data Center, Oberpfaffenhofen, Germany
        o NOAA National Geophysical Data Center, Boulder, Colorado, USA
        o USGS EROS Data Center, Sioux Falls, South Dakota, USA

     For more details see: www.ngdc.noaa.gov/seg/topo/globe.shtml

     Data Base Assembly

     The five major data sources were assembled into the single ETOPO2
     2-minute data base without formal edge matching or other methods
     that alter the data as initially posted. Higher-resolution data
     take precedence: data derived from GLOBE mask all other data,
     Smith/Sandwell data come next, followed by IBCAO, with the 5-minute
     data filling any gaps.

     Five-minute data from DBDBV and ETOPO5 and 30-second data from
     GLOBE were regridded to 2 minute spacing by bicubic spline
     interpolation. IBCAO data were originally gridded in a polar
     stereographic projection; these data were interpolated along lines
     of constant latitude at 2 minute steps for every 2 minutes of
     latitude from 72— North to the pole.

     Gridded Data Format

     The data are cell-centered, with an array size of 10800 columns x
     5400 rows; coverage is from 180— West to 179— 58' East and 90— North
     to 89— 58' South. A data record for the South Pole is not in these
     files -- assume 2810m as the elevation.