The GEOSAT Altimeter Mission: A milestone in satellite oceanography

Cheney, Robert E.; Douglas, Bruce C.; Agreen, R. W.; Miller, Laury; Milbert, Dennis; Porter, David

doi:10.1029/eo067i048p01354

Cited by 35 publications

(18 citation statements)

References 9 publications

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“…The accuracy of the measurements will improve as the accuracy and coverage of satellite altimeter data improves. The Geosat mission [Cheney et al, 1986] demonstrates that altimeter accuracies can be improved by a factor of 4 over the Seasat accuracy. This improves the along-track resolution by nearly a factor of 2.…”

Section: Resultsmentioning

confidence: 99%

Global distribution of seamounts from Seasat profiles

Craig

Sandwell

1988

J. Geophys. Res.

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Bathymetrie profiles and contour charts have been used to study the distribution of seamounts in the deep ocean basins, but only a small fraction of the seafloor has been sampled by ships. At the present exploration rate it will take several centuries to map significant portions of the seafloor topography. Satellite altimetry, which maps the topography of the equipotential sea surface, is a promising tool for studying the gravity fields of seamounts because all ocean basins can be sampled in a couple of years. Using a model of a Gaussian‐shaped seamount loading a thin elastic lithosphere, we develop a new technique for measuring basic characteristics of a seamount from a single satellite altimeter profile. The model predicts that the seamount diameter is equal to the peak‐to‐trough distance along the vertical deflection profile and that the overall diameter of the signature reveals the age of the lithosphere when the seamount formed. Moreover, the model suggests that these two measurements are relatively insensitive to the cross‐track location of the seamount. We confirm these model predictions using Seasat altimeter profiles crossing 14 well surveyed seamounts in the Pacific. We then apply the measurement technique to 26 × 106 million kilometers of Seasat profiles resulting in a new global set of seamount locations. Approximately one quarter of the seamounts identified in Seasat profiles were previously uncharted. Modeling suggests that there is no direct relationship between the size of a seamount and its signature in the geoid; therefore the set of locations is not a straightforward sampling of the total seamount population, but is weighted toward seamounts which are poorly compensated. A preliminary analysis indicates considerable variations in population density and type across the oceans; most notable among them are the absence of seamounts in the Atlantic, variations in population density across large age‐offset fracture zones in the Pacific, the prevalence of small signatures in the Indian Ocean, and the existence of linear trends in the large seamounts of the west Pacific.

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Section: Resultsmentioning

confidence: 99%

Global distribution of seamounts from Seasat profiles

Craig

Sandwell

1988

J. Geophys. Res.

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“…Detailed description of the data set was given by Cheney et al (1987). Standard data corrections were made using values provided in the GDR (Geophysical Data Record).…”

Section: Sea Surface Dynamic Topographymentioning

confidence: 99%

Eddy activities of the surface layer in the western North Pacific detected by satellite altimeter and radiometer

Aoki

Imawaki

1996

J Oceanogr

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“…First is the uncertainty of the marine geoid, which is the sea level variation associated with the Earth gravity field and is far more energetic than the oceanic signal [e.g., Tai, 19833. However, there are ways to get around the geoid problem by differencing sea level measurements at the same location (this occurs where satellite ground tracks cross each other [called crossover points] or when tracks are repeated), such as the exact-repeat strategy and the crossover analysis [e.g., Fu and Chelton, 1985;Cheney et al, 1986].…”

Section: Introductionmentioning

confidence: 99%

Geosat crossover analysis in the tropical Pacific: 1. Constrained sinusoidal crossover adjustment

Tai

1988

J. Geophys. Res.

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A new method (called constrained sinusoidal crossover adjustment) for removing the orbit error in satellite altimetry is tested (using crossovers accumulated in the first 91 days of the Geosat nonrepeat era in the tropical Pacific) and found to have many excellent qualities. Two features distinguish the new method from the conventional bias‐and‐tilt crossover adjustment. First, a sine wave (with wavelength equaling the circumference of the Earth) is used to represent the orbit error for each satellite revolution, instead of the bias‐and‐tilt (and curvature, if necessary) approach for each segment of the satellite ground track. Second, the indeterminacy of the adjustment process is removed by a simple constraint that minimizes the amplitudes of the sine waves rather than by fixing selected tracks. Overall, the new method is more accurate, more efficient, and much less cumbersome to implement than the old method. The idea of restricting the crossover adjustment to crossovers between tracks that are less than certain days apart in order to preserve the large‐scale long‐term oceanic variability is also tested with inconclusive results because the orbit error was unusually nonstationary in the initial 91 days of the Geosat mission.

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The GEOSAT Altimeter Mission: A milestone in satellite oceanography

Cited by 35 publications

References 9 publications

Global distribution of seamounts from Seasat profiles

Global distribution of seamounts from Seasat profiles

Eddy activities of the surface layer in the western North Pacific detected by satellite altimeter and radiometer

Geosat crossover analysis in the tropical Pacific: 1. Constrained sinusoidal crossover adjustment

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