HR: 16:15h
AN: G44A-02 INVITED     [Abstracts]
TI: High resolution (10 km, 3mGal) gravity mapping of the Global continental margins using ERS1 and Geosat satellite altimeter data
AU: * Fairhead, J D
EM: jdf@getech.leeds.ac.uk
AU: Green, C M
EM: cmg@getech.leeds.ac.uk
AU: Fletcher, K M
EM: kmuf@getech.leeds.ac.uk
AB: Converting sea-surface height variations, derived from satellite altimetry, to free air gravity is not new. What is new is our ability to use existing satellite data to resolve anomalies down to 10 km wavelength and to within 2 to 5 km of the coast globally. Since 1993, GETECH, University of Leeds, has been involved in developing new methods and techniques to recover gravity from satellite altimeter data with the specific aim of improving oil exploration methods in deep-water areas of the continental margins, worldwide. By a combination of new processing methods, we can recover anomalies that are accurately and reliably representing geological structures down to 10 km in wavelength. These improvements have been possible by applying: -advanced seismic repicking methods to recover the onset of ERS-1 radar waveforms; -a range of more accurate and globally consistent wet and dry Troposphere propagation and tidal corrections; -careful data editing and validation based on data visualisation techniques; -micro-levelling to resolve discrepancies between satellite tracks in order to derive a reliable geoid surface; and -the `Geoid to Gravity' conversion method which has significant advantages over existing methods The methodology has allowed us to map to within 2 and 5 km of the coast, globally, and significantly suppress noise that is prevalent and dominates existing solutions at 40 km and shorter wavelengths. At these and shorter wavelengths the geological signal is effectively masked by the noise. The global continental margins study was completed in June 2004 and examples of the resolution improvements for the Gulf of Mexico and S E Asia are shown. Key words: Satellite gravity, high-resolution, continental margins.
DE: 1219 Local gravity anomalies and crustal structure
DE: 1234 Regional and global gravity anomalies and Earth structure
DE: 1241 Satellite orbits
DE: 1243 Space geodetic surveys
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting