Detection of uncharted seamounts using satellite altimetry

Lazarewicz, Andrew P.; Schwank, D. C.

doi:10.1029/gl009i004p00385

Cited by 53 publications

(16 citation statements)

References 5 publications

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“…This marine gravity anomaly data set has provided uniform and dense data coverage over all oceans and has enabled researchers to investigate both remote bathymetric features unexplored by oceangoing expeditions (e.g. Lazarewicz & Schwank 1982; Cazenave et al 1983; Watts & Ribe 1984; Mammerickx 1992; McAdoo & Marks 1992; Small & Sandwell 1994) as well as large‐scale deep‐seated geophysical phenomena (e.g. Haxby & Weissel 1986; McAdoo & Sandwell 1989; McNutt 1998).…”

Section: Introductionmentioning

confidence: 99%

New global seamount census from altimetry-derived gravity data

Kim¹,

Wessel²

2011

Geophysical Journal International

118

128

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S U M M A R YRecent revisions to the satellite-derived vertical gravity gradient (VGG) data reveal more detail of the ocean bottom and have allowed us to develop a non-linear inversion method to detect seamounts in VGG data. We approximate VGG anomalies over seamounts as sums of individual, partially overlapping, elliptical polynomial functions, which allows us to form a non-linear inverse problem by fitting the polynomial model to the observations. Model parameters for a potential seamount include geographical location, peak VGG amplitude, major and minor axes of the elliptical base, and the azimuth of the major axis. The non-linear inversion is very sensitive to the initial values for the location and amplitude; hence, they are constrained by the centre and amplitude of the uppermost contours obtained with a 1-Eötvös contour interval. With these initial conditions from contouring, we execute a step-wise and fully automated inversion and obtain optimal model estimates for potential seamounts; these are statistically evaluated for significance using the Akaike Information Criterion and F tests. A logarithmic barrier technique is applied to ensure positivity of all seamount amplitudes. After automatic and manual inspections of the model parameters we estimate actual heights and basal ellipses of the inspected potential seamounts directly from the predicted bathymetry grid. In this study, we find globally 24 643 potential seamounts (h ≥ 0.1 km) that are located away from continental margins; 8458 potential seamounts are taller than 1 km. Although our global estimate is significantly lower than predictions from previous studies, a first-order reconciliation of the size-frequency statistics obtained from those studies reveals that the previous counts are systematically overestimated. Because of the ambiguity of gravity signals due to small seamounts of h < 1 km and the overlap with abyssal hills, we estimate the global seamount census to lie in the 40 000-55 000 range. The seamount data from this study are accessible from http://www.soest.hawaii.edu/PT/SMTS.

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Section: Introductionmentioning

confidence: 99%

New global seamount census from altimetry-derived gravity data

Kim¹,

Wessel²

2011

Geophysical Journal International

118

128

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“…Seamounts are apparent in GEOS-3 and Seasat altimeter profiles because they produce small bumps in the sea surface or geoid [Lambeck and Coleman, 1982;Lazarewicz and Schwank, 1982;Sandwell, 1984a, b]. With Seasat data, the along-track position of a seamount can be determined to an accuracy of 10 km or less.…”

Section: Introductionmentioning

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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“…Such grids have different spacings in latitude and longitude, with the typical step size of 0.5° x 0.5°. The grids have been used for a variety of applications [Lazarewicz and Schwank, 1982], especially for correlating the high-and medium-frequency part of the gravity field with bathymetry [e.g., Cazenave et ai, 1983]. Equal-angular 1° x 1° mean free air gravity anomalies have also been derived, generally by collocation [Rapp, 1979[Rapp, , 1983, and used in global geopotential models in spherical harmonics [Reigber et ai, 1985].…”

Section: Introductionmentioning

confidence: 99%

Free air gravity anomalies over the oceans from Seasat and GEOS 3 altimeter data

Balmino¹,

Moynot²,

Sarrailh³

et al. 1987

EoS Transactions

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Satellite altimetry measurements have been used extensively in the last few years to compute local or global grids of values of geoid heights with respect to a given reference ellipsoid [see Balmino et al., 1979; Marsh and Martin, 1982; Marsh et al., 1982; Marsh et al., 1984[. Such grids have different spacings in latitude and longitude, with the typical step size of 0.5°×0.5°. The grids have been used for a variety of applications [Lazarewicz and Schwank, 1982], especially for correlating the high‐ and medium‐frequency part of the gravity field with bathymetry [e.g., Cazenave et al., 1983[. Equal‐angular 1°×1° mean free air gravity anomalies have also been derived, generally by collocation [Rapp, 1979, 1983a,b], and used in global geopotential models in spherical harmonics [Reigber et al., 1985].

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Detection of uncharted seamounts using satellite altimetry

Cited by 53 publications

References 5 publications

New global seamount census from altimetry-derived gravity data

New global seamount census from altimetry-derived gravity data

Global distribution of seamounts from Seasat profiles

Free air gravity anomalies over the oceans from Seasat and GEOS 3 altimeter data

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