Journal of Tropical Oceanography >
Submesoscale characteristics of a typical anticyclonic mesoscale eddy in Kuroshio Extension*
Copy editor: LIN Qiang
Received date: 2020-12-26
Revised date: 2021-03-01
Online published: 2021-03-03
Supported by
Original Innovation Project of Basic Frontier Scientific Research Program of CAS(ZDBS-LY-DQC011)
National Natural Science Foundation of China(92058201)
National Natural Science Foundation of China(41776040)
Innovation Academy of South China Sea Ecology and Environmental Engineering, CAS(ISEE2018PY05)
Copyright
Using satellite measurements and high-resolution ROMS simulations, we analyze submesoscale characteristics of a typical anticyclonic mesoscale eddy in the Kuroshio Extension. Both satellite observations and high-resolution simulations show obvious submesoscale phenomena in the vortex region in the Kuroshio Extension. Our analysis results show that the strength of submesoscale kinetic energy is in close connection with kinetic energy of geostrophic velocity, which means that the frontogenesis may be an important way to enhance the submesoscale kinetic energy in the eddy periphery. Our analysis of the eddy’s vertical constructure shows submesoscale process can induce strong vertical velocity, which can be up to 100 m·day-1. The strong vertical velocity can reach a depth of hundreds of meters, indicating that submesoscale process can provide an efficient way for sea surface-internal material exchanging and air-sea interactions.
Key words: mesoscale eddy; submesoscale process; front; Kuroshio Extension
ZHANG Xu , JING Zhiyou , ZHENG Ruixi , HUANG Xiaolong , CAO Haijin . Submesoscale characteristics of a typical anticyclonic mesoscale eddy in Kuroshio Extension*[J]. Journal of Tropical Oceanography, 2021 , 40(6) : 31 -40 . DOI: 10.11978/2020152
图2 卫星观测的5月3日黑潮延伸体气候态SST和水平流速(箭头)(a), 以及SLA(c)和模式模拟的第21年5月3日黑潮延伸体SST、水平流速(b)及SLA(d)分布图c、d中黑色曲线为气候态平均海面高度等值线, 用以表示黑潮延伸体主轴的大致位置 Fig. 2 Spatial distributions of SSH (shading) and surface currents (vector), and SLA of the Kuroshio Extension provided by remote sensing satellite (a, c) and ROMS mode (b, d). The black contours in (c) and (d) are SSH, which indicate the location of the Kuroshio Extension axis. |
图4 涡旋发展前期(a—c)、中期(d—f)和后期(g—i)表层SKE的水平分布黑色线为涡旋外边界, 红色线为涡旋中心外边界 Fig. 4 Surface submesoscale kinetic energy distributions in early (a-c), mid (d-f), and late (g-i) development stages of the eddy. Eddy boundary and eddy core are marked by black and red curves in each panel, respectively |
图5 涡旋边缘(蓝线, 单位: 10-3m2·s-2)与涡旋中心(红线, 单位: 10-3m2·s-2)的平均次中尺度动能及涡旋边缘(绿线, 单位: 10-16s-5)与涡旋中心(紫线, 单位: 10-16s-5)锋生函数的时间演变曲线Fig. 5 Time series of SKE in eddy periphery (blue curve), eddy center (red curve), and front function in eddy periphery (green curve) and eddy center (purple curve) |
图6 模拟结果第21年5月3日涡旋海域的海表面温度、水平流速(箭头)(a)与罗斯贝数Ro(b)的水平分布a中白色线为等温线; b中黑色实线为下文所分析的37°30'N断面位置 Fig. 6 Maps of SST (a) and Ro (b) from the R2 simulation. The vectors and white contours in (a) are for surface currents and isotherms, respectively. The black line in (b) is the location of the 37°30'N section analyzed later in the paper |
图9 锋面强度(填色)及垂向次中尺度流速异常ω’(箭头)(a)、锋生函数(b)、罗斯贝数(c)和垂向浮力通量(d)的37°30'N断面分布a中灰色曲线为混合层深度(采用密度阈值法计算, σ=0.03kg·m-3); a—d中黑色竖直线为涡旋边缘与中心的分界 Fig. 9 Vertical profiles of frontal sharpness (shading), vertical velocity anomaly (black arrows) (a), front function (b), Ro (c), and bouncy flux (d). The grey curve in (a) represents the mixed-layer depth, and the black lines in each panel separate the eddy center and periphery |
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