Impact of West Antarctic ice shelf melting on Southern Ocean hydrography

• Published in: The Cryosphere
• Main Authors: Nakayama, Yoshihiro, Timmermann, Ralph, Hellmer, Hartmut H
• Format: Article in Journal/Newspaper
• Language: unknown
• Published: Copernicus Publications 2020
• Subjects: Antarctic; Southern Ocean; Weddell Sea; Ross Sea; Weddell; Darnley; Cape Darnley; Antarc*; Ice Shelf; Ice Shelves; Sea ice; The Cryosphere
• Online Access: https://epic.awi.de/id/eprint/58269/; https://epic.awi.de/id/eprint/58269/1/Nakayama_et_al_2020__TC.pdf; https://doi.org/10.5194/tc-14-2205-2020; https://hdl.handle.net/10013/epic.743ee887-63a0-4df3-9179-f6e0a75eab5b

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 not been well 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 can propagate further downstream along the East Antarctic coast into the Weddell Sea. The freshening signal propagates onto the RS continental shelf within a year of model simulation, while it takes roughly 5-10 and 10-15 years to propagate into the region off Cape Darnley and into the Weddell Sea, respectively. This advection of freshening modulates the shelf water properties and possibly impacts the production of Antarctic Bottom Water if the enhanced melting of West Antarctic ice shelves continues for a longer period.