Bathymetric prediction from SEASAT altimeter data

Abstract

The linear response function technique is used to analyze two 1300‐km tracks of SEASAT altimeter data and corresponding bathymetry in the Musician Seamounts region north of Hawaii. Bathymetry and geoid height are highly correlated in the 50‐ to 300‐km wavelength range. A predictive filter is developed which can operate on SEASAT altimetry in poorly surveyed oceanic regions to indicate the presence of major bathymétrie anomalies. Modeling of the bathymetry‐geoid correlation in the Musician region is attempted using the elastic plate model. The flexural rigidity D of the plate is not well constrained by our data but appears to lie in the range 5×1021 N m ‐ 5×1022 N m at the time of loading. Since the Musician Seamounts and the crust on which they lie are both Late Cretaceous in age, this value represents the effective flexural rigidity of very young lithosphere that was ‘frozen in’ at the time of voicanism, The modeling indicates that the general form of a predictive filter will strongly depend on various geologic parameters, especially the effective flexural rigidity. Hence, some a priori geologic constraints are necessary to estimate successfully the bathymetry from the altimeter data. Alternately, if high‐quality bathymetry is available, a crude estimate of the age of loading (i.e., voicanism) can be made from the altimeter data.

Isostatic Compensation and Conduit Structures of Western Pacific Seamounts: Results of Three-Dimensional Gravity Modeling

“…A major contribution to the marine geoid is made by seafloor bathymetry, because of the large density contrast at the rock-water interface. Attempts have therefore been made to use satellite altimeter data to predict bathymetry (e.g., Lazarewicz and Schwank, 1982;Dixon et al, 1983). Such a tool would be especially asd'ul in the South and West Pacific where ship crossings are rare.…”

“…(1984) showed that the Seasat radar altimetry and seafloor topography over Bermuda and Gregg Seamount could not be described adequately by a single transfer function. Dixon et al (1983) and Watts and Ribe (1984) related the variations in amplitude of marine geoid anomalies over seamounts to different effective elastic thicknesses of the flexed lithosphere beneath the seamounts. The effective elastic thicknesses are related to the tectonic settings of the seamounts, that is, whether they formed on or near a mid-oceanic ridge crest or off-ridge.…”

A Synoptic Review on Deriving Bathymetry Information Using Remote Sensing Technologies: Models, Methods and Comparisons

“…There are a number of complications that need careful handling; the most important ones are 1) computing bathymetry from gravity anomalies is possible over a limited wavelength band, and 2) longer wavelengths are highly dependent on the elastic thickness of the lithosphere. The feasibility study of a bathymetry calculation technique based on the one-dimensional filtering of SEASAT tracks is published elsewhere [9]. Fundamentally, the algorithm is based on the linear approximation of the relationship between the geoid and a given density contrast interface.…”

“…Altimetry-derived bathymetry also reveals plate boundaries and oceanic plateaus. The basic theory for deducing seafloor topography from satellite altimeter measurements is summarized elsewhere [9]. The conceptual approach uses the sparse in situ depth soundings to restrict the long-wavelength depth while the shorter-wavelength topography is inferred from the downward-continued satellite gravity measurements [10] [47].…”

“…However, this method is limited by the coarse bathymetric sampling interval and high cost. The basic assumption for deriving ocean bed topography from satellite altimeter measurements (non-imaging method) is summarized elsewhere [9]. The conceptual approach employs the sparse depth sounding measurements to restrict the long-wavelength depth while the shorter-wavelength topography is envisaged from the downward-continued satellite gravity measurements [10].…”