First Results of Recovery of Short Wavelength Gravity Field Signals from CryoSat-2 Data

A number of geophysical phenomena in the open ocean are still unresolved by conventional 1 Hz altimetry, but could be observed through the potential improvements offered by SAR, or Delay-Doppler (DD), altimetry. The DD altimeter offers the following benefits with respect to conventional satellite altimetry: Factor of 20 improvements in along track resolution.

Along-track footprint length that does not vary with wave height (sea state). Improved precision in sea surface height measurements / sea surface slope measurements. These improvements are studied with respect to retrieval of short wavelength geophysical signal related to mainly bathymetric features.

The combination of upward continuation from the sea bottom and smoothing the altimeter observations resulted in the best recovery of geophysical signal for simulated 5-Hz DD observations. The first validation of these theoretical modeling results with respect to resolution and noise are presented using various CryoSat-2 data and evaluation against conventional Radar altimeter data from older GM missions onboard ERS-1 is presented.

A comparison of L2 products for LRM, SAR and SAR-in data are carried out with re-tracked L1 data for the same data types.