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Ocean Sci., 8, 37-48, 2012
www.ocean-sci.net/8/37/2012/
doi:10.5194/os-8-37-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.


The impacts of physical processes on oxygen variations in the North Sea-Baltic Sea transition zone

L. Jonasson1,2, J. L. S. Hansen3, Z. Wan1, and J. She1
1Danish Meteorological Institute, Lyngbyvej 100, 2100 Copenhagen, Denmark
2Niels Bohr Institute, University of Copenhagen, Juliane Maries Vej 30, 2100 Copenhagen, Denmark
3National Environmental Research Institute, Aarhus University, Frederiksborgvej 399, 4000 Roskilde, Denmark

Abstract. The bottom water of the North Sea–Baltic Sea transition zone suffers from seasonal hypoxia, usually during late summer and autumn. These hypoxic events are critical for the benthic ecosystems and the concentration of dissolved oxygen is an important measure of the water quality. However, to model the subsurface dissolved oxygen is a major challenge, especially in estuaries and coastal regions. In this study a simple oxygen consumption model is coupled to a 3-D hydrodynamical model in order to analyse oxygen variations in the transition zone. The benthic and pelagic consumption of oxygen is modelled as a function of water temperature and oxygen concentration. A quantitative assessment of the model demonstrates that the model is able to resolve both seasonal and interannual variations in dissolved oxygen. Results from several experimental simulations highlight the importance of physical processes in the regulation of dissolved oxygen. Advective oxygen transport and wind induced mixing are two key processes that control the extent of hypoxia in the transition zone.

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Citation: Jonasson, L., Hansen, J. L. S., Wan, Z., and She, J.: The impacts of physical processes on oxygen variations in the North Sea-Baltic Sea transition zone, Ocean Sci., 8, 37-48, doi:10.5194/os-8-37-2012, 2012.   Bibtex   EndNote   Reference Manager    XML