Andrea Hay (University of Tasmania, Australia); Benoit Legresy (CSIRO, Australia); Matt King (University of Tasmania, Australia); Boye Zhou (University of Newcastle, Australia); Jack Beardsley (University of Tasmania, Australia); Alejandro Bohé (CNES, France)

Located within the SWOT fast-sampling phase track, the long-term Bass Strait altimeter validation facility (-40.6°S, 145.6°E) and the Southern Ocean Flux Station (SOFS, -47°S, 142°E), provide two important validation targets in geographically diverse locations in the southern hemisphere. In preparation for SWOT, both sites were augmented with GNSS instrumentation enabling the validation of SWOT satellite observations including sea surface height (SSH), significant wave height (SWH) and tropospheric wet path delay. Commencing with the SOFS location, we review results validating SWOT wave parameters in this highly energetic region of the Southern Ocean. Shifting focus to the Bass Strait facility, we review the geometric approach to validation which is enabled through the deployment of an array of GNSS equipped buoys, with moored oceanographic sensors proving complementary information. We first present results investigating signal delay induced by water vapor in the troposphere. Over short spatial scales (<∼80 km), we find that this signal is not well-captured by SWOT radiometer observations and hence may bias geophysical interpretation. We then review our SSH and SWH validation results which provide independent in situ measurement evidence of the outstanding performance of the KaRIn instrument. We conclude with perspectives on the utility of the geometric approach to the validation of future wide-swath altimeter missions.