NRSC Regional Marine Geoid

The NRSC's Regional Geoid Product offers the most accurate satellite derived measurement of the marine geoid, providing an inexpensive base dataset for rapid geophysical screening of off-shore sedimentary basins. The product consists of corrected mean sea surface heights referenced to an Earth Ellipsoid. Vertical accuracy's of better than 10cm are achieved through the application of NRSC's waveform-retracking process. Accurate measurement of the marine geoid is important for exploration companies who use the information to derive gravitational fields over offshore basins. These are used to map potential oil-bearing structures beneath the ocean floor. The geoid is generated from Altimeter data acquired by the European Space Agency's ERS-1 satellite, from both the 35-day repeat cycle phase or the 168-day repeat cycle (geodetic phase). The unique retracked dataset produced by the NRSC enables the derivation of precise high frequency geoid information for the first time. Features of the 35-day repeat cycle product include: > Five repeat orbits are used to reduce errors > Vertical accuracy is better than 10cm > Along track resolution is 7km > Across track resolution at 60 degrees latitude is 39km. This is four times more dense than available from previous altimeter-derived datasets such as the Haxby global geoid > Data for the Arctic basin is available for the first time Features of the 168-day repeat cycle product include: > Along track resolution is 2km (resolutions up to 0.5km are available, however the location accuracy of the altimeter sensor is limited to 2km) > Across track resolution at 60 degrees latitude is 4km > Vertical accuracy is around 10cm The Regional Geoid Product consists of geoid undulation heights referenced to a long wavelength geoid model. These are available as a series of points along the original satellite tracks or as a regular gridded dataset. Products are available 'off-the-shelf' for major sedimentary basins including: North East Europe, the Falklands shelf, South East Asia and the Barents and Kara Seas. Products for any other area between 80N and 80S can be generated on demand. The data is supplied in digital form on Exabyte, CD-ROM or CCT. Further details and pricing are available from the National Remote Sensing Centre (NRSC).