496 / 2024-09-18 08:14:58

The linkage of Dense Shelf Water production in the Ross Sea with large-scale climate forcing

Ross Sea,Dense Shelf Water,Southern Annular Mode,Polynyas

The Antarctic Bottom Water (AABW), which supplies the lower limb of the thermohaline circulation, originates from dense shelf water (DSW) forming in Antarctic polynyas. Combining the longest mooring record of DSW measurements in the Southern Ocean, numerical simulations and satellite data, we show that significant correlation can exist between interannual variability of DSW production in polynyas of the Ross Sea that contributes between 20–40% of the global AABW production and the Southern Annular Mode (SAM). The correlation is largest when the Amundsen Sea Low (ASL) is weakened and further away from the Ross Sea. During positive SAM phases, enhanced offshore winds over the western Ross Sea increase sea ice production and promote DSW formation, with the opposite response occurring during negative SAM phases. These processes finally modulate AABW thickness in the open ocean of the Pacific sector. The projected trend in SAM toward its positive phase and the ASL moving further from the Ross Sea has implications for the future of DSW and AABW.