The density and salinity of High Salinity Shelf Water, a key component of Antarctic Bottom Water emanating from the Ross Sea, are intensified by brine rejection induced by ice formation within the Terra Nova Bay (TNB) polynya. Ocean mooring data from 2007, meteorological observations from automatic weather stations and a satellite-derived history of the opening of TNB polynya delineate variability in water column salinity linked to atmospheric forcing, with a period on the order of 10 days. Lagged correlation analysis indicates that on average salinity response lags the polynya opening by 2 days and the wind forcing by 5 days. We find stronger correlations of salinity with the wind during March through May and with the polynya open-water fraction during June through October, with decreasing lags in the latter period. A one-dimensional mixed-layer model incorporating thermodynamic ice formation captures the oscillations in salinity. A process study shows that the variability in the polynya open-water fraction governs the final salinity attained by the model as well as the salinity cycling. Variability in surface heat fluxes modulates that effect. Our work suggests that there is a more complex relationship between salinity, the polynya open-water fraction, and atmospheric forcing than previously suggested.

At monthly and annual timescales, the zonally asymmetric circulation over the Southern Ocean is dominated by two quasi-stationary anticyclones: a western anticyclone approximately located south of New Zealand, and an eastern anticyclone located over the Drake Passage region. In this research their influence on late 20th century Antarctic sea ice is explored. During early winter, sea ice in the Weddell, Amundsen and Bellingshausen seas is influenced by the location of the east anticyclone. During late winter, the strength and location of the west anticyclone influences sea ice primarily in the Ross and Amundsen seas. The anticyclones have some effect on wind-driven sea ice motion, but the primary mechanism explaining their link to sea ice appears to be meridional atmospheric thermal advection. A western shift in the west anticyclone may be partly responsible for observed increases in ice cover in the Ross Sea over the late 20th century, but there is little evidence in existing data to support a link between the east anticyclone and observed sea ice trends.