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Submesoscale eddies near the Kuril Straits: Asymmetric generation of clockwise and counterclockwise eddies by barotropic tidal flow

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Title: Submesoscale eddies near the Kuril Straits: Asymmetric generation of clockwise and counterclockwise eddies by barotropic tidal flow
Authors: Nakamura, T. Browse this author →KAKEN DB
Matthews, J. P. Browse this author
Awaji, T. Browse this author
Mitsudera, H. Browse this author
Keywords: Kuril Islands
North Pacific Ocean
Issue Date: 12-Dec-2012
Publisher: American Geophysical Union
Journal Title: Journal of Geophysical Research: Oceans
Volume: 117
Issue: C12
Start Page: C12014
Publisher DOI: 10.1029/2011JC007754
Abstract: High spatial resolution thermal infrared (TIR) images derived by the LANDSAT Thematic Mapper (TM) sensors show the presence of numerous small-scale eddies near the Kuril Islands. As the diameters of these eddies range from around 2 to 30 km (i.e., submesoscale), they are much smaller than the eddies previously reported in this region (several tens to some hundreds of kilometers in diameter). Our simulations suggest that small-scale eddies similar to those observed in the satellite data are generated by diurnal barotropic tides. The eddy generation is well defined from Etorofu/Friza to the Onnekotan Straits, and it is caused by the effects of coastal boundaries and the stretching of water columns, which lead to eddy growth even after eddies have left the coast. We find that the counterclockwise eddies are generally larger in number and size and stronger in vorticity and surface height than the clockwise eddies in both the gradient and cyclostrophic wind balance regimes. The possible causes of such asymmetry are (1) the effect of planetary-vorticity tube stretching, which can be significant even when the final relative vorticity becomes much greater than planetary vorticity and (2) asymmetric advection by the rotating tidal flow, which advects counterclockwise eddies offshore but clockwise eddies onshore. These eddies induce strong stirring with a maximum apparent diffusivity of 10^[8] cm2 s^[-1]. The numbers, properties, and mixing effects of eddies vary greatly with the spring-neap cycle.
Rights: ©2012 American Geophysical Union
Type: article
Appears in Collections:低温科学研究所 (Institute of Low Temperature Science) > 雑誌発表論文等 (Peer-reviewed Journal Articles, etc)

Submitter: 中村 知裕

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