Preliminary gravity recovery from CryoSat-2 data in the Baffin Bay

Abstract

A number of geophysical phenomenons in the open ocean are still unresolved by conventional altimetry, but could be resolved through the potential improvements offered by Synthetic Aperture Radar (SAR), also called Delay-Doppler, altimetry. The SAR altimeter offers the following benefits with respect to conventional satellite altimetry: factor of 20 improvements in the along-track resolution, the along-track footprint length which does not vary with wave height (sea state), and improved precision in sea surface height measurements or sea surface slope measurements.In this paper these improvements are studied with respect to retrieval of short wavelength geophysical signal related to mainly bathymetric features. In an analysis of simulated data it was found that the combination of upward continuation from the sea bottom and smoothing of the altimeter observations meant that the best recovery of geophysical signal was achieved from measurements averaged to 5Hz, rather than the simulated 20Hz full resolution data. A first validation of these theoretical modelling results with respect to resolution and noise is presented using various CryoSat-2 data, and evaluated against conventional radar altimeter data from the older ERS-1 Geodetic Missions.