Looking through Southern Ocean sea-ice: new insights into the ice-covered Southern Ocean circulation from multi-altimeter combination.

Subtle changes in the Southern Ocean subpolar ocean circulation patterns can lead to major changes in the global overturning circulation, as well as for floating ice-shelves with critical implications for global sea-level. It is therefore crucial to carefully understand Antarctic polar ocean circulation, but the lack of ocean observation has considerably blocked our advance in this field in the past.

In this study we present a new high-resolution Sea Level Anomaly (SLA) product that has been specifically constructed to document sea-level in ice-covered the Southern Ocean. This product combines up to 4 satellite altimetry missions to map SLA data daily on an equal-area grid, including the ice-covered areas of the ocean from 2002 to 2018. High resolution satellite radar altimeter measurements are mapped on an EASE-2 grid using an objective analysis method derived from current CMEMS processing, with a dedicated processing and updated mapping parameters over the area.

Preliminary results suggest that we can map ocean features with unprecedented resolution for the region. Validation is performed by comparing to tide gauges and independent altimeter measurements. Our results offer a new view to Southern Ocean circulation at high resolution and over the past 15 years. In particular, we investigate Weddell and Ross gyres annual cycles and behavior, and more generally Southern Ocean subpolar circulation at several scales including mesoscale variability where possible, intra-seasonal and seasonal variability, and long-term trends.