CoAuthors

Paolo Cipollini (National Oceanography Centre, UK); Hausman Jessica (Jet Propulsion Laboratory (JPL), California Institute of Technology , Pasadena, California, USA); Quartly Graham (Plymouth Marine Laboratory, UK); Snaith Helen (British Oceanographic Data Centre, UK)

Improvements in coastal altimetry are now bringing new possibilities to studies of coastal dynamics and coastal sea level and allow the exploitation of synergies with the other components of the coastal observing systems (gauges, buoys, mooring, HF radars, floats) and with regional models. Those improvements come from technological advances in altimeters (i.e. the SAR mode altimeter on board CryoSat-2 and soon Sentinel-3) as well as improved processing techniques (better waveform retracking and data screening) and corrections.
Our research has focused on the retracking, i.e. the on-ground processing that fits a model to the signal received by the satellite in order to increase the precision of the estimated geophysical parameters. This study will present its outcome, i.e. a new global multi-mission coastal-retracked altimetry dataset based on the ALES (Adaptive Leading-Edge Sub-waveform retracker) algorithm. ALES aims at retracking both open ocean and coastal data with the same precision, and is therefore tailored to the needs of the coastal and shelf oceanographers and modellers.
As an introduction we present the details of the algorithm and summarize its validation against in-situ measurements of tide gauges (TGs) located in the Adriatic Sea and on the Agulhas Bank. We also briefly recall the validation of the Significant Wave Height (SWH) against buoy data in the German Bight. We show a couple of example applications of the reprocessed data to sea level variability studies and coastal oceanography in the Danish Straits and in the Indonesian Sea.
We finally describe the coastal altimetry datasets deriving from the application of ALES to the entire Jason-1, Jason-2 and Envisat missions in the global coastal strip. This dataset is being made available free of charge from the Physical Oceanography Distributed Active Archive Center (PO.DAAC) at the NASA Jet Propulsion Laboratory, Pasadena, CA. http://podaac.jpl.nasa.gov. The file structure is the same as standard SGDR products, with the addition of the fields concerning the ALES retracking, i.e. range and SWH. Users are invited to integrate the new retracked fields with state-of-the-art geophysical corrections in order to maximise the impact of the improvements.