Using High-Resolution Altimetry to Observe Mesoscale Signals

An Ocean System Simulation Experiment is used to quantify the observing capability of the Surface Water and Ocean Topography (SWOT) mission and its contribution to higher-quality reconstructed sea level anomaly(SLA)fields using optimalinterpolation. The paper focuseson the potentialof SWOT for mesoscale observation(wavelengthslargerthan100 kmandtimeperiodslargerthan10 days)anditsabilitytoreplaceor complement altimetry for classical mesoscale applications. For mesoscale variability, the wide swath from SWOTprovides anunprecedentedsamplingcapability.SWOTalonewouldenabletheregionalsurfacesignal reconstruction as precisely as a four-altimeter constellation would, in regions where temporal sampling is optimum.For somespecificslatitudes,whereswathsamplingisdegraded,SWOTcapabilitiesare reducedand show performances equivalent to the historical two-altimeter constellation. In this case, merging SWOT with the two-altimeter constellation stabilizes the global sampling and fully compensates the swath time sampling limitations. Benefits of SWOT measurement are more important within the swath. It would allow a precise local reconstruction of mesoscale structures. Errors of surface signal reconstruction within the swath represent less than 1% (SLA) to 5% (geostrophic velocities reconstruction) of the signal variance in a pessimistic roll error reduction. The errors are slightly reduced by merging swath measurements with the conventional nadir measurements.

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