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Cross-shelf exchange in the northwestern Black Sea

March 18, 2014

The transports of water, heat and salt between the northwestern shelf and deep interior of the Black Sea are investigated using a high-resolution three-dimensional primitive equation model. From April to August, 2005, both onshore and offshore cross-shelf break transports in the top 20 m were 0.24 Sv on average, which is equivalent to the replacement of 60% of the volume of surface shelf waters (0 – 20 m) per month. Two main exchange mechanisms are studied: Ekman transport, and transport by mesoscale eddies and associated meanders of the Rim Current. The Ekman drift causes nearly uniform onshore or offshore flow over a large section of the shelf break, but it is confined to the upper layers. In contrast, eddies and meanders penetrate deep down to the bottom, but they are restricted laterally. During the strong wind events of April 15 – 22 and July 1 – 4, some 0.66×1012 and 0.44×1012 m3 of water were removed from the northwestern shelf respectively. In comparison, the single long-lived Sevastopol Eddy generated a much larger offshore transfer of 2.84×1012 m3 over the period April 23 to June 30, which is equivalent to 102% of the volume of northwestern shelf waters. Over the study period, salt exchanges increased the average density of the shelf waters by 0.67 kg m-3 and reduced the density contrast between the shelf and deep sea, while lateral heat exchanges reduced the density of the shelf waters by 0.16 kg m-3 and sharpened the shelf break front.

 Zhou F,  Shapiro G, Wobus F, in press: Cross-shelf exchange in the northwestern Black Sea, Journal of Geophysical Research: Oceans, doi:10.1002/2013JC009484. Article.


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