Regional Seafloor Topography by Extended Kalman Filtering of Marine Gravity Data without Ship-Track Information
Résumé
Abstract: An iterative Extended Kalman Filter (EKF) approach is proposed to recover a regional set
of topographic heights composing an undersea volcanic mount by the successive combination of
large numbers of gravity measurements at sea surface using altimetry satellite-derived grids and
taking the error uncertainties into account. The integration of the non-linear Newtonian operators
versus the radial and angular distances (and its first derivatives) enables the estimation process
to accelerate and requires only few iterations, instead of summing Legendre polynomial series
or using noise-degraded 2D-FFT decomposition. To show the effectiveness of the EKF approach,
we apply it to the real case of the bathymetry around the Great Meteor seamount in the Atlantic
Ocean by combining only geoid height/free-air anomaly datasets and using ship-track soundings as
reference for validation. Topography of the Great Meteor seamounts structures are well-reconstructed,
especially when regional compensation is considered. Best solution gives a RMS equal to 400 m with
respect to the single beam depth observations and it is comparable to RMS obtained for ETOPO1 of
about 365 m. Larger discrepancies are located in the seamount flanks due to missing high-resolution
information for gradients. This approach can improve the knowledge of seafloor topography in
regions where few echo-sounder measurements are available.
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