Pelagos-4 resolves winter shift in Southern Ocean boundary current

A three-year record from the Pelagos-4 radar altimeter has resolved the winter movement of a major Southern Ocean boundary current south of Ainare at a scale not available in earlier national datasets. The result improves estimates of wave energy, coastal heat transport and the seasonal position of productive ocean fronts.

Researchers combined 10-day repeat altimetry with calibrated sea-surface temperature, wind and autonomous profiling-float observations. The analysis shows that the current's northern boundary shifts an average of 38 kilometres toward Ainare during late winter, with substantial year-to-year variation linked to persistent wind patterns.

The updated field is already being incorporated into the National Coastal Forecast System. Port authorities, fisheries researchers and emergency planners will receive revised boundary-current and extreme-wave products beginning with the August operational cycle.

The complete calibrated altimetry series, uncertainty model and reproducible processing software have been released through the ANSA Science Data Archive. The study was reviewed under the agency's open-methods and research-integrity requirements.