Global Seafloor Topography from Satellite Altimetry
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On Monday, October 23, 1995 NOAA's Geoscience Laboratory and the Scripps Institution of Oceanography (SIO) held a joint press conference to describe a new image of ocean floor structures made from recently available satellite data. The map was derived from satellite altimeter data collected by the European Space Agency and the US Navy. NOAA's National Oceanographic Data Center distributes the raw data from the US Navy's GEOSAT satellite. The data can be processed to reveal tiny changes in the pull of gravity. These changes are usually caused by mountains and valleys on the ocean floor, so gravity maps are useful in revealing the geology of the sea floor. However, gravity is not topography (depth). It is possible to predict depths by combining gravity data with ship surveys of depth. The authors are currently analyzing the available data to produce a database of inferred or "predicted" topography. Although the image displayed has been referred to by the press as a "Detailed map of ocean floor" it is actually a preliminary map of global seafloor gravity anomalies. Copies of this (approximately 3 x 5 foot) gravity map are available from SIO (see link above under Posters).
A published map of The Measured and Estimated, or "Predicted," Global Seafloor Topography was completed and made available in mid-1997 (see top of this page).