A detailed gravity field over the Reykjanes Ridge from Seasat, Geosat, ERS‐1 and TOPEX/POSEIDON altimetry and shipborne gravity

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Abstract
The method of least‐squares collocation (LSC) was used to construct a detailed gravity field over the Reykjanes Ridge using Seasat, Geosat, ERS‐1, TOPEX/POSEIDON altimeter data and shipborne gravity data. Mean altimeter‐derived geoid gradients, along with their standard deviations, were used in order to avoid cross‐over adjustment of sea surface heights. The ship data were adjusted to a satellite‐only gravity field using a quadratic polynomial in time and then merged with the satellite data to produce a combined gravity field. The necessary covariance functions were derived using the law of covariance propagation. In a test case, a comparison between a combined gravity field and ship data not included in the calculation yielded an rms difference of 2.31 mgals. The combined gravity field contains a wealth of short‐wavelength information and clearly reveals the detailed tectonic structures associated with the Reykjanes Ridge.