Airborne Gravimetry from a Light Aircraft
Over the past decade, as airborne gravity data acquisition and reduction has become increasingly refined, its usage by academic, industrial and government researchers has expanded. Recent data collected jrom a Cessna 404 over water and a ski-equipped Twin Otter over a grounded ice sheet, have demonstrated that airborne gravity can recover anomalies with wavelengths greater than about 5 kilometers to accuracies of better than 3 mGal. The Cessna 404 was used over the Long Island Sound off the East Coast of the U.S., a region with extensive marine and land ground truth. The output from the Bell Aerospace BGM-3 was reduced with psuedorange GPS positioning from a Trimble 4000 CA-code receiver and with vertical positions and accelerations from a radar altimeter. The Twin Otter experiment was flown over the West Antarctic Rift system, where limited ground truth from surface gravity data exists that was collected in the early 1960’s. The navigation in this experiment included CA-code and P-code psuedorange solutions, differential carrier phase positions, radio transponder locations and pressure altimetry. Base stations were used for the differential GPS and pressure altimetry. The results from an overflight of a traverse gravity line indicate that even in this remote location airborne gravity can recover anomalies with accuracy adequate for geologic studies. The current level of resolution and accuracy from airborne gravity is adequate for tectonic studies and deciphering the history of sedimentary basins but it falls short of the high resolution required for detailed studies of intrusive features, hydrothermal deposits and other small, yet important, geologic features. To increase the accuracy and resolution of the airborne measurements utilizing the current systems requires improved positioning systems, stabilized platforms and improved sensors. Gravity gradiometry may also prove to be an important technique as it eliminates some of the stringent requirements for high resolution navigation.
KeywordsGlobal Position System Gravity Field Gravity Data Differential Global Position System Airborne Gravity
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- Ashjaee, J., New results on the accuracy of the C/A code GPS receivers, in Proceeding First International Symposium on Precise Positioning with the Global Positioning System, U.S. Department of Commerce, 207–225, 1985.Google Scholar
- Bell, R.E., High resolution marine and airborne gravity surveys: applications to rifted margins, PhD thesis, Columbia University, 1989.Google Scholar
- Bell, Robin E., John M. Brozena, William F. Haxby and John L. LaBrecque, Continental Margins of the Western Weddell Sea: Insights from Airborne Gravity and Geosat-Derived Gravity, Contributions to Antarctic Research, 1,1990Google Scholar
- Bell, R.E., B.J. Coakley and R.W. Stemp, Airborne gravimetry from a small twin engine aircraft over the Long Island Sound, Geophys., 1990.Google Scholar
- Bentley, C.R. and N.A. Ostenso, 1961. Glacial and subglacial topography of West Antarctica. Journal of Glaciology, 3 (29), 882–910, 1961.Google Scholar
- Browne, B.C., The measurement of gravity at sea, Monthly Notes of the Roy. Soc., Geophy. Sup., 4, 271–279, 1938.Google Scholar
- Dehlinger, P. and D.R. Hutchinson, Long Island and Block Island Sound Free-Air Gravity Anomaly Maps, Unpublished report, 1986.Google Scholar
- Eötvös, R., Experimenteller Nachweis der Schwereanderung die ein auf normal geformter Erdoberflache in Ostlicher oder westlicher Richtung bewegter Korper durch diese Bewegung erleidet, Ges. Arbe. Budapest, 293–305,1953. (published in 1919 in Annalen der Physik) Google Scholar
- Gumert, W.R., G.F. Wertz and R.M. Iverson, An application study for using differential GPS in airborne gravity, in Proceeding First International Symposium on Precise Positioning with the Global Positioning System, U.S. Department of Commerce, 829–832, 1985.Google Scholar
- Moritz, H, The geodetic reference system 1967, Allgemeine Vermessungs Nachrichten, 75, 2–7, 1968.Google Scholar
- Navasio, F. and W. Gumert, Airborne gravity–1980’s, Geophysics, 47, 447,1982.Google Scholar
- Wells, D.E., A. Kleusberg, S.H. Quek, J. McCullouch and J. Hagglund, Precise ship’s velocity from GPS:some test results, in Proceedings First International Symposium on Precise Positioning*with the Global Positioning System, U.S. Department of Commerce, 799–808,1985.Google Scholar