Marine gravity anomaly from Geosat and ERS 1 satellite altimetry

Closely spaced satellite altimeter profiles collected during the Geosat Geodetic Mission (-6 km) and the ERS 1 Geodetic Phase (8 km) are easily converted to grids of vertical gravity gradient and gravity anomaly. The long-wavelength radial orbit error is suppressed below the noise level of the altimeter by taking the along-track derivative of each profile. Ascending and descending slope profiles are then interpolated onto separate uniform grids. These four grids are combined to form comparable grids of east and north vertical deflection using an iteration scheme that interpolates data gaps with minimum curvature. The vertical gravity gradient is calculated directly from the derivatives of the vertical deflection grids, while Fourier analysis is required to construct gravity anomalies from the two vertical deflection grids. These techniques are applied to a combination of high-density data from the dense mapping phases of Geosat and ERS 1 along with lower-density but higher-accuracy profiles from their repeat orbit phases. A comparison with shipboard gravity data shows the accuracy of the satellite- derived gravity anomaly is about 4-7 mGal for random ship tracks. The accuracy improves to 3 mGal when the ship track follows a Geosat Exact Repeat Mission track line. These data provide the first view of the ocean floor structures in many remote areas of the Earth. Some applications include inertial navigation, prediction of seafloor depth, planning shipboard surveys, plate tectonics, isostasy of volcanoes and spreading ridges, and petroleum exploration.

[1]  Karen M. Marks.  Resolution of the Scripps/NOAA marine gravity field from satellite altimetry , 1996 .

[2]  B. Parsons,et al.  An optimal procedure for deriving marine gravity from multi‐satellite altimetry , 1996 .

[3]  Investigation of Methods for Global Gravity Field Recovery from the Dense ERS-1 Geodetic Mission Altimetry , 1996 .

[4]  Improved resolution of Geosat altimetry using dense sampling and polynomial adjusted averaging , 1995 .

[5]  Cheinway Hwang,et al.  Gravity anomalies derived from Seasat, Geosat, ERS‐1 and TOPEX/POSEIDON altimetry and ship gravity: a case study over the Reykjanes Ridge , 1995 .

[6]  Walter H. F. Smith,et al.  New version of the generic mapping tools , 1995 .

[7]  Walter H. F. Smith,et al.  Comparison of along‐track resolution of stacked Geosat, ERS 1, and TOPEX satellite altimeters , 1995 .

[8]  A. Cazenave,et al.  Geoid lineations of 1000 km wavelength over the central Pacific , 1995 .

[9]  D. Chambers,et al.  Accuracy assessment of the large‐scale dynamic ocean topography from TOPEX/POSEIDON altimetry , 1994 .

[10]  Bob E. Schutz,et al.  Gravity model development for TOPEX/POSEIDON: Joint gravity models 1 and 2 , 1994 .

[11]  C. Shum,et al.  Determination of ocean tides from the first year of TOPEX/POSEIDON altimeter measurements , 1994 .

[12]  S. Bettadpur,et al.  Geographical representation of radial orbit perturbations due to ocean tides: Implications for satellite altimetry , 1994 .

[13]  Walter H. F. Smith,et al.  Bathymetric prediction from dense satellite altimetry and sparse shipboard bathymetry , 1994 .

[14]  Sarah T. Gille,et al.  Mean sea surface height of the Antarctic circumpolar current from Geosat data : method and application , 1994 .

[15]  S. Laxon,et al.  Arctic Ocean Gravity Field Derived From ERS-1 Satellite Altimetry , 1994, Science.

[16]  P. Visser,et al.  GEOSAT and ERS-1 radar altimetry over the North Atlantic , 1993 .

[17]  D. Sandwell,et al.  Comparison of marine gravity from shipboard and high‐density satellite altimetry along the Mid‐Atlantic Ridge, 30.5°–35.5°S , 1993 .

[18]  Dynamic sea surface topography from GEOSAT altimetry , 1993 .

[19]  Walter H. F. Smith.  On the accuracy of digital bathymetric data , 1993 .

[20]  Walter H. F. Smith,et al.  Marine gravity derived from GEOSAT , 1993 .

[21]  P. Vogt,et al.  Predicting bathymetry from Geosat-ERM and shipborne profiles in the South Atlantic Ocean , 1992 .

[22]  David T. Sandwell,et al.  Antarctic marine gravity field from high-density satellite altimetry , 1992 .

[23]  William Menke,et al.  Applications of the POCS inversion method to interpolating topography and other geophysical fields , 1991 .

[24]  Walter H. F. Smith,et al.  Gridding with continuous curvature splines in tension , 1990 .

[25]  Gravity gradients from satellite altimetry , 1990 .

[26]  David T. Sandwell,et al.  Global mesoscale variability from the Geosat Exact Repeat Mission - Correlation with ocean depth , 1989 .

[27]  A. Watts,et al.  On the accuracy of marine gravity measurements , 1988 .

[28]  W. Roest.  Seafloor spreading pattern of the North Atlantic between 10o and 40o N : a reconstruction based on shipborne measurements and satellite altimeter data , 1987 .

[29]  B. Parsons,et al.  Seasat‐derived gravity over the Musicians Seamounts , 1986 .

[30]  K. Marks,et al.  Comparison of GEOS‐3 and SEASAT Altimeter Resolution Capabilities , 1986 .

[31]  J. Weissel,et al.  Evidence for Small-Scale Mantle Convection From Seasat Altimeter Data , 1986 .

[32]  D. Sandwell.  A detailed view of the South Pacific geoid from satellite altimetry , 1984 .

[33]  J. L. LaBrecque,et al.  Digital images of combined oceanic and continental data sets and their use in tectonic studies , 1983 .

[34]  R. Brammer.  Estimation of the ocean geoid near the Blake Escarpment using Geos 3 satellite altimetry data , 1979 .

[35]  A. Watts,et al.  On geoid heights derived from Geos 3 altimeter data along the Hawaiian‐Emperor Seamount Chain , 1979 .

[36]  Ian Briggs.  Machine contouring using minimum curvature , 1974 .

[37]  W. M. Kaula.  Theory of satellite geodesy , 1966 .