Journal cover Journal topic
Ocean Science An interactive open-access journal of the European Geosciences Union
Ocean Sci., 13, 837-849, 2017
https://doi.org/10.5194/os-13-837-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
25 Oct 2017
A modelling study of eddy-splitting by an island/seamount
Shengmu Yang1,2, Jiuxing Xing1, Daoyi Chen1,2, and Shengli Chen1 1Shenzhen Key Laboratory for Coastal Ocean Dynamic and Environment, Graduate School at Shenzhen, Tsinghua University, Shenzhen, 518055, China
2School of Environmental Science and Engineering, Tsinghua University, Beijing, 100084, China
Abstract. A mesoscale eddy's trajectory and its interaction with topography under the planetary β and nonlinear effects in the South China Sea are examined using the MIT General Circulation Model (MITgcm). Warm eddies propagate to the southwest while cold eddies propagate to the northwest. The propagation speed of both warm and cold eddies is about 2.4 km day−1 in the model. The eddy trajectory and its structure are affected by an island or a seamount, in particular, under certain conditions, the eddy may split during the interaction with an island/seamount. We focus this research on two parameters R and S (where R and S are two dimensionless parameters of the island size and submergence depth; R is the ratio of the island radius to the eddy radius, and S is the ratio of the seamount submergence depth to the eddy vertical length). The results of sensitivity experiments with varying island or seamount geometry indicate that the eddy would split in the qualitative range of 1∕4  <  R  <  2 and S  <  1∕5. The scale of the secondary eddy split-off decreases as the island diameter or the seamount submergence depth increases. In the splitting process, besides the off-spring eddy, there are also some filaments or eddies with opposite vorticity appearing around the eddy. Eddy-splitting, therefore, is an important way to transform energy from the mesoscale to sub-mesoscale in the ocean.

Citation: Yang, S., Xing, J., Chen, D., and Chen, S.: A modelling study of eddy-splitting by an island/seamount, Ocean Sci., 13, 837-849, https://doi.org/10.5194/os-13-837-2017, 2017.
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Short summary
Motivated by eddy-splitting near Dongsha island, the eddy's trajectory and the effect of topography on eddy evolution were explored using the MITgcm. Warm eddies propagate to the southwest while cold eddies propagate to the northwest in open oceans. The results of the model indicate that the eddy would split in a qualitative range, and the location of the eddy split-off is related to the island size. In addition, eddy-splitting is an important way to transform energy between different scales.
Motivated by eddy-splitting near Dongsha island, the eddy's trajectory and the effect of...
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