High resolution coastal gravity anomalies from retracked Geosat/GM and ERS-1/GM altimetry
University of Newcastle,
University Drive, Callaghan,
The paper presents the high resolution (1 minute by 1 minute) gravity anomalies using corrected sea surface heights (SSHs) derived from non-repeat Geosat and ERS-1 Geodetic Missions (GMs) in the Australian coast. The SSHs have an along-track resolution of ~3 km (2 Hz) and are obtained from retracking the altimetric waveform data. Retracking algorithms are developed to reduce the noise effect and improve the accuracy of the range estimate (and thus the SSHs). The retracking technique also estimates the parameters of the off-nadir angle and significant wave height. These estimates are then analysed to find their error characteristics. Different retracking algorithms applied to coastal regions are also analysed. The SSH profiles derived from retracking waveforms of Geosat and ERS-1 GMs are now more accurate and much closer to the coast than those without a retracking procedure, thus providing optimised data sources for gravity field and mean sea surface recovery in coastal regions. Finally, the recovered gravity anomalies are compared with ship-born gravity observations.