OS Ocean Science OS Ocean Sci. 1812-0792 Copernicus Publications Göttingen, Germany 10.5194/os-7-305-2011 On the freshening of the northwestern Weddell Sea continental shelf Hellmer H. H. 1 Huhn O. 2 Gomis D. 3 Timmermann R. 1 Alfred Wegener Institut für Polar und Meeresforschung, Bremerhaven, Germany Institut für Umweltphysik, Universität Bremen, Bremen, Germany IMEDEA, Universitat de les Illes Balears – CSIC, Mallorca, Spain 06 05 2011 7 3 305 316 Copyright: © 2011 H. H. Hellmer et al. 2011 This work is licensed under the Creative Commons Attribution 3.0 Unported License. To view a copy of this licence, visit https://creativecommons.org/licenses/by/3.0/ This article is available from https://os.copernicus.org/articles/7/305/2011/os-7-305-2011.html The full text article is available as a PDF file from https://os.copernicus.org/articles/7/305/2011/os-7-305-2011.pdf

We analyzed hydrographic data from the northwestern Weddell Sea continental shelf of the three austral winters 1989, 1997, and 2006 and two summers following the last winter cruise. During summer a thermal front exists at ~64° S separating cold southern waters from warm northern waters that have similar characteristics as the deep waters of the central basin of the Bransfield Strait. In winter, the whole continental shelf exhibits southern characteristics with high Neon (Ne) concentrations, indicating a significant input of glacial melt water. The comparison of the winter data from the shallow shelf off the tip of the Antarctic Peninsula, spanning a period of 17 yr, shows a salinity decrease of 0.09 for the whole water column, which has a residence time of <1 yr. We interpret this freshening as being caused by a combination of reduced salt input due to a southward sea ice retreat and higher precipitation during the late 20th century on the western Weddell Sea continental shelf. However, less salinification might also result from a delicate interplay between enhanced salt input due to sea ice formation in coastal areas formerly occupied by Larsen A and B ice shelves and increased Larsen C ice loss.

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