About Satellite Geodesy
Provided by the Scrippts Institute of Oceanography of the University of San Diego, CA.
Etymologically speaking the word geodesy comes from the Greek:
GE: The Earth DAIEIN: To share
Geodesy is the field of science that is involved in the measurement of the size and shape of the earth as well as its gravity field. Modern geodetic tools such as the global positioning system (GPS), radar altimetry, laser altimetry, synthetic aperture radar, and satellite-to-satellite tracking are accurate enough to monitor time variations in the earth related to plate tectonics, post-glacial, ocean circulation and atmospheric circulation.
Modern geodesy attempts to solve geophysical problems by assimilating observable phenonema (such as variations in the Earth's rotation, gravity, geocenter, and surface deformations) into models. Today, these observations come from a variety of sources including Satellite Laser Ranging (SLR), Very-Long-Baseline Interferometry (VLBI), the Global Positioning System (GPS), and Doppler Orbitography and Radiopositioning Integrated by Satellite (DORIS).
Access the Data
Contents of the Data
This data consists of 33 files of global topography in the same format as the SRTM30 products distributed by the USGS EROS data center. The grid resolution is 30 second which is roughly one kilometer.
Land data are based on the 1-km averages of topography derived from the USGS SRTM30 grided DEM data product created with data from the NASA Shuttle Radar Topography Mission. GTOPO30 data are used for high latitudes where SRTM data are not available.
Ocean data are based on the Smith and Sandwell global 1-minute grid between latitudes +/- 81 degrees. Higher resolution grids have been added from the LDEO Ridge Multibeam Synthesis Project, the JAMSTEC Data Site for Research Cruises, and the NGDC Coastal Relief Model. Arctic bathymetry is from the International Bathymetric Chart of the Oceans (IBCAO) [Jakobsson et al., 2003].
The pixel-registered data are stored in 33 files with names corresponding to the upper left corner of the array shown below. The data are also merged into a single large (1.9 Gbyte, 2-byte integer) file as well as smaller 1-minute and 2-minute netcdf versions. Matching files of source identification number are available for determining the data source for every pixel.