Benoit Legresy (CSIRO, Australia); Andrea Hay (University of Tasmania, Australia); Jack Beardsley (University of Tasmania, Australia); Boye Zhou (University of Tasmania, Australia); Matt King (University of Tasmania, Australia)

The Bass Strait altimeter validation facility (~ 40°39’S, 145°36’ E) continues to provide cycle-by-cycle estimates of absolute altimeter bias for the altimeter reference missions. The facility maintains an in situ network of sensors including moored oceanographic instruments, GNSS equipped buoys, a coastal tide gauge and continuously operating GNSS reference stations. Specific components of this instrumentation have recently been enhanced in line with the evolution in high spatial resolution altimetry. These advancements seek to improve noise characteristics and our ability to sample localised and higher frequency SSH signals.

We detail our ongoing use of 5-beam ADCP instruments for the determination of shallow water SSH, current and wave field information using a pressure inverted echo sounder concept (PIES). We detail our approach to constrain the absolute datum of these sustained SSH time series using GNSS/INS equipped buoys, and knowledge of ongoing vertical land motion determined from land-based GNSS sites. Updated absolute bias results and comparisons of local estimates of tropospheric water content for the Sentinel-6/Michael Freilich mission are presented using latest release data. We conclude with an early perspective of what we are able to infer from higher resolution along track sampling over the duration of the SWOT Fast Sampling Phase, noting our in situ sampling was aligned with the Sentinel-6/Michael Freilich pass over the facility.