Impact of West Antarctic Ice Shelf melting on the Southern Ocean Hydrography

• Main Authors: Nakayama, Yoshihiro, Timmermann, Ralph, Hellmer, Hartmut
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: COPERNICUS GESELLSCHAFT MBH 2020
• Subjects: Antarc*; Antarctic; Ice Shelf; Ice Shelves; Ross Sea; Sea ice; Southern Ocean; Weddell Sea
• Online Access: https://epic.awi.de/id/eprint/52630/; https://epic.awi.de/id/eprint/52630/1/Nakayama-etal_2020.pdf; https://doi.org/10.5194/tc-2019-244; https://hdl.handle.net/10013/epic.d6baafc4-eac7-4333-916c-3cbebb872625

Previous studies show accelerations of West Antarctic glaciers, implying that basal melt rates of these glaciers were previously small and increased in the middle of the 20th century. This enhanced melting is a likely source of the observed Ross Sea (RS) freshening, but its long-term impact on the Southern Ocean hydrography has never been investigated. Here, we conduct coupled sea-ice/ice-shelf/ocean simulations with different levels of ice shelf melting from West Antarctic glaciers. Freshening of RS shelf and bottom water is simulated with enhanced West Antarctic ice shelf melting, while no significant changes in shelf water properties are simulated when West Antarctic ice shelf melting is small. We further show that the freshening caused by glacial meltwater from ice shelves in the Amundsen and Bellingshausen Seas propagates further downstream along the East Antarctic coast into the Weddell Sea. Our experiments also show the timescales for the freshening signal to reach other regions around the Antarctic continent. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5–10 years and 10–15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening signal} possibly modulates the properties of dense shelf water and impacts the production of Antarctic Bottom Water.