期刊
JOURNAL OF GEOPHYSICAL RESEARCH-OCEANS
卷 123, 期 11, 页码 8548-8567出版社
AMER GEOPHYSICAL UNION
DOI: 10.1029/2018JC014196
关键词
oceanic eddy; eddy characteristics; eddy generation mechanisms; Kuroshio Extension region
类别
资金
- National Key Research Program of China [2017YFA0604100, 2016YFC1401407, 2016YFA0601803]
- NSFC [41476022, 41490643, 41621064, 91528304]
- Jiangsu Province Science Foundation for Youths [BK20150897]
- Startup Foundation for Introducing Talent of Nanjing University of Information Science and Technology [2013r121, 2014r072]
- Program for Innovation Research and Entrepreneurship Teams in Jiangsu Province
- National Basic Research Program [2013CB430302]
- National Natural Science Foundation of China [91528304, 41321004, 41606022]
- National Natural Science Foundation of China (National ScienceFoundation of China for Outstanding Young Scientist) [41622604]
- National Natural Science Foundation of China (Excellent Youth Science Foundation of Jiangsu Province) [BK2016090]
- National Program on Global Change and Air-Sea Interaction [GASI-IPOVAI-02, GASI-IPOVAI-04, GASI-IPOVAI-05]
- Postgraduate Research & Practice Innovation Program of Jiangsu Province [KYLX16_0925]
- China Ocean Mineral Resources Research and Development Association program [DY135-E2-3-01]
- Natural Science Foundation of Jiangsu Province [BK20150897]
- National 973 Program of China [2014CB745000]
The Kuroshio Extension region is well known for its strong eddy activity. In this paper, using satellite altimetry-measured sea surface height anomaly data from 1993 to 2012 in an extended Kuroshio Extension region (140-180 degrees E, 25-45 degrees N), we analyze eddy characteristics: eddy size, polarity, lifetime, intensity, trajectory, and spatial and temporal distributions. Using temperature and salinity vertical profiles measured by Argo floats, we examine the eddy impact on vertical stratification. During the 20-year period, 7,574 eddies are identified (based on following complete eddy trajectories) with a lifetime equal to or longer than 4weeks. The numbers of cyclonic and anticyclonic eddies are found to be approximately the same. The distribution of eddy sizes peaks at a radius of about 40km. The radius at the peak is at the same order as the first baroclinic deformation radius or the horizontal shear scale of the Kuroshio flow. The normalized eddy statistical characteristics show that eddies have different characteristics at different stages of their lifetimes. Among eddies with lifetimes longer than 50weeks, more anticyclonic (cyclonic) eddies are found north (south) of 35 degrees N. In contrast, among eddies with lifetimes shorter than 20weeks, more cyclonic (anticyclonic) eddies are found north (south) of 35 degrees N. The asymmetric distribution of eddies suggests two different eddy generation mechanisms: (1) the development of meanders in the Kuroshio path leading to the pinch off of eddies with longer lifetime (larger size) and (2) horizontal shear instability (barotropic instability) leading to eddies of shorter life (smaller size). We further apply an eddy-resolved numerical product to quantitatively investigate the eddy generation mechanisms. Plain Language Summary We analyze eddy characteristics with 20-year satellite data and examine the eddy impact on vertical stratification. Besides, through the statistic result, we propose two eddy generation mechanisms: flow horizontal shear-induced eddy generation and the meander of flow path leading to the eddy generation. And then, we further apply an eddy-resolved numerical product to quantitatively investigate the eddy generation mechanisms.
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