Change in dense shelf water and Adelie land bottom water precipitated by iceberg calving

• Published in: Geophysical Research Letters
• Main Authors: Snow, K, Rintoul, SR, Sloyan, BM, Hogg, AMC
• Format: Article in Journal/Newspaper
• Language: English
• Published: Amer Geophysical Union 2018
• Subjects: Earth Sciences; Oceanography; Physical Oceanography; Antarctic; The Antarctic; Adelie Land; Antarc*; Iceberg*
• Online Access: https://doi.org/10.1002/2017GL076195; http://ecite.utas.edu.au/131899

Antarctic Bottom Water supplies the deep limb of the global overturning circulation and ventilates the abyssal ocean. Antarctic Bottom Water has warmed, freshened, and contracted in recent decades, but the causes remain poorly understood. We use unique multiyear observations from the continental shelf and deep ocean near the Mertz Polynya to examine the sensitivity of this bottom water formation region to changes on the continental shelf, including the calving of a large iceberg. Postcalving, the seasonal cycle of Dense Shelf Water (DSW) density almost halved in amplitude and the volume of DSW available for export reduced. In the deep ocean, the density and volume of Adelie Land Bottom Water decreased sharply after calving, while oxygen concentrations remained high, indicating continued ventilation by DSW. This natural experiment illustrates how local changes in forcing over the Antarctic continental shelf can drive large and rapid changes in the abyssal ocean.