Dense Shelf Water properties and current velocity observations from a moored observatory in the Ross Sea

• Main Authors: Castagno, P., Falco, P., Krauzig, N., Garzia, A., Memmola, F., Cotroneo, Y., Budillon, G.
• Format: Conference Object
• Language: English
• Published: 2023
• Subjects: Antarctic; Ross Sea; Terra Nova Bay; Antarc*
• Online Access: https://gfzpublic.gfz-potsdam.de/pubman/item/item_5021374

Antarctic Bottom Water (AABW) supplies the lower branch of the global overturning circulation and ventilates the abyssal ocean. Changes in AABW properties and formation rate propagate into the global ocean and affect stratification, sea level, heat content, and the carbon cycle. Approximately 25% of AABW originates from the Dense Shelf Water (DSW) produced on the Ross Sea continental shelf. Understanding the long-term variability of the Ross Sea DSW physical properties and its controlling factors is critical to assessing the AABW variability. Here we use an unprecedented 28 years of current velocity and hydrographic observations collected from a mooring situated in Terra Nova Bay (TNB), where the saltiest DSW is produced. We used these time series to analyze the ocean currents in relation to dense water formation. While recent studies have suggested that the tides are the dominant source of currents close to the Ross Sea shelf break, here we observe a negligible contribution of the tide to the total velocity. We find a strong seasonal variability with a strong barotropic (from 140 m to the bottom) along trough (north-eastward) flow during August to October at the peak of dense water formation, suggesting a correlation between the flow rate at the mooring and the DSW production. Moreover, to investigate the relationship between the dense water production and the AABW outflow from the continental shelf, we have also compared the TNB mooring observations to the time series registered close to the shelf break.