Abstract

Intense atmosphere-ocean-ice interactions in the Ross Sea play a vital role in global overturning circulation by supplying saline and dense shelf waters. Since the 1960s, freshening of the Ross Sea shelf water has led to a decline in Antarctic Bottom Water formation. Since the early 2010s, however, the salinity of the western Ross Sea has rebounded. This study adopts an ocean-sea ice model to investigate the causes of this salinity rebound. Model-based salinity budget analysis indicates that the salinity rebound was driven by increased brine rejection from sea ice formation, triggered by the nearly equal effects of local anomalous winds and surface heat flux. The local divergent wind anomalies promoted local sea ice formation by creating a thin ice area, while a cooling heat flux anomaly decreased the surface temperature, increasing sea ice production. This highlights the importance of understanding local climate variability in projecting future dense shelf water change.