Along track analysis of a GNSS/INS buoy array in the context of Sentinel‐6 and future SWOT altimetry validation at the Bass Strait facility
As part of the assessment of Sentinel-6 high-rate (20 Hz) high-resolution data and in preparation for the future swath data from SWOT, various improvements to in situ instrumentation at the Bass Strait validation facility have been explored. An array of six new GNSS/INS equipped Mk-VI buoys have been developed and deployed for an 8-day trial deployment along Sentinel-6 pass 088. Five deployment locations with up to 10 km spacing were used, centred on the historical Jason-series comparison point. Two new buoys and a single buoy of the previous design were deployed within ~200 m of each other at the nominal Jason-series comparison point, allowing for inter-comparison.
Here we investigate the buoy array as a relatively low-cost, flexible, yet high precision method for validation of high-rate and high-resolution altimetry. We investigate differences in oceanic processes and conditions observed by the array, namely tidal effects and significant wave height. We also explore the ability of the buoys to observe the passage of weather systems that create intra-swath variability in the case of the future SWOT mission. We seek to understand the SLA data in Bass Strait from an oceanography perspective – it highlights the tidal resonance in the shallow water area driven by high wind conditions. Under the assumption of geostrophic balance in the deployed area, we compare inferred geostrophic current with in-situ current meter observations in order to better understand the expected performance of the buoy array in future swath-based altimetry validation. We conclude with the comparison of buoy solutions against a single overflight using Sentinel-6 high-rate (20 Hz) high-resolution data for initial assessment of both high-rate high-resolution altimetry product and the quality of the buoy array solutions.