Improvements in Satellite Gravity - Getting Closer to the Coast

CryoSat-2 provides new radar altimetry data that can be integrated with data from previous satellites to develop new marine satellite gravity grids. The new satellite gravity is seen to provide improved resolution. Coastal areas are problematic due to reflections from land interfering with sea surface reflections. Our algorithm for calculating sea-surface height from satellite altimetry is improved by simultaneous inversion (re-tracking) of a number of waveforms, but this means that contaminated waveforms can have a wide impact. CryoSat-2 can provide data slightly closer to coasts by editing based on the “peakiness” (ratio of maximum power to mean power) of each radar waveform. This process has been carefully tuned based on the characteristics of the CryoSat-2 waveforms and of the algorithm used to invert them. However, this simple removal of contaminated waveforms means that significant data volumes are lost. The next generation of waveform re-trackers should remove spurious signals from the waveforms, based on an understanding of the geometric relationship between adjacent waveforms and local topography.