HR: 0800h
AN: G31C-0818    [Abstracts]
TI: Airborne LaCoste&Romberge Gravimetry; an Alternative Computation Approach
AU: * ABBASI, M
EM: madjid.abbasi@obs-mip.fr
AF: Bureau Gravimetrique International (BGI), UMR5562, Observatoire Midi-Pyrenees, Toulouse, 31400 France
AU: BARRIOT, J
EM: jean-pierre.barriot@cnes.fr
AF: Bureau Gravimetrique International (BGI), UMR5562, Observatoire Midi-Pyrenees, Toulouse, 31400 France
AU: VERDUN, J
EM: verdun@ensg.ign.fr
AF: Ecole Nationale des Sciences Geographiques (ENSG), 6 et 8 avenue Blaise-Pascal, Marne la Vallee, 77455 France
AU: DUQUENNE, H
EM: henri.duquenne@ensg.ign.fr
AF: Ecole Nationale des Sciences Geographiques (ENSG), 6 et 8 avenue Blaise-Pascal, Marne la Vallee, 77455 France
AB: The problem of separation of the accelerations sensed by an airplane and the gravity signal at flight height is the main problem of airborne gravimetry. The generally used method is the low pass filtering of the measured parameters. This is based on the assumption that the airplane induced accelerations have a high frequency nature while the gravity acceleration is a low frequency signal. The cut-off frequency is usually not higher than 0.01 Hz. This corresponds to 6 km at a mean speed of 60 m/s, meaning that the gravity acceleration with lower wavelength is overfiltered. This is basically because of the numerical differentiation of the time series. We have developed a method based on integral equations and least squares estimation. By taking into account the covariance matrices of the observations and the a priori unknowns, as well as the the mathematical formulation of the gravimeter as a spring-damper system, we obtain results with an improved contents on the high frequency band. The method is applied to the data acquired over the French Alpes mountains.
DE: 1200 GEODESY AND GRAVITY
DE: 1219 Local gravity anomalies and crustal structure
DE: 1294 Instruments and techniques
SC: Geodesy [G]
MN: 2004 AGU Fall Meeting