Towards a 1 mGal accuracy and 1 min resolution altimetry gravity field
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Over the past three decades, radar altimetry has made a significant contribution to marine gravity field modeling. To improve the accuracy and resolution, we propose a new twin-satellite altimetry. Such a system has several advantages. Among others, it provides (i) twice the number of samples per time epoch, and (ii) information about the cross-track surface gradient with high accuracy because most of the environmental and tidal errors will be common to the simultaneous measurements and therefore cancel out when computing the cross-track gradient computation. We describe a rigorous procedure for the deduction of the sea surface gradient at each altimeter observation point (i.e., not only at the crossovers), from the twin-satellite altimetry system. The precision of the gradient will be slightly affected by orbit errors, instrument drift, and inaccuracies in the geophysical corrections to be applied. We also demonstrate that a 1 mGal accuracy and 1 min resolution marine altimetry gravity field can be obtained if certain conditions are met. To achieve the expected goal, we recommend an orbital configuration, phasing two satellites in 4-s time delay such that the Earth rotation creates a natural baseline between the two satellites, and a 18 kHz SAR altimeter.
KeywordsMarine altimetry gravity Sea surface gradient Sea surface slope
This research was supported by the National Natural Science Foundation of China (Grant: 41274050), Public Science and Technology Research Funds Projects of Ocean of China (201405027-2) and Science and Technology Project of National Administration of Surveying, Mapping and Geo-information of China (K201101). We thank the editor and reviewers for suggesting improvements to the manuscript.
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