Seasonal evolution of upper‐ocean horizontal structure and the remnant mixed layer
Seasonal evolution of upper‐ocean horizontal structure and the remnant mixed layer
复制标题
上层海洋水平结构和残余混合层的季节演化
DOI：
10.1029/2009jc005654
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发表时间：
2010
影响因子：
--
通讯作者：
J. Colosi
中科院分区：
文献类型：
--
作者：
S. Cole;D. Rudnick;J. Colosi
[1]本文讨论了小水平尺度上上层海洋温盐结构的季节演变。在北太平洋副热带1000公里长的断面上350米的位置进行了冬、春、夏三季的观测，水平分辨率为3-14公里。四个垂直区域具有明显的密度和盐度结构：混合层，残余混合层，高分层和永久温跃层。剩余混合层是由冬季混合层中的水组成的。冬季和春季残留混合层与混合层最为相似，夏季残留混合层与其下的高层结最为相似。高层化层有升高的分层，季节性变化。永久温跃层的季节变化不大，水平和垂直比较均匀。在所有季节，密度比表明，混合层θ-S差异往往在密度补偿，最强的补偿趋势在冬季。密度比温度占主导地位的残余混合层与盐指一致。盐度异常最大的表面和衰减的深度在所有季节。比较了三个季节四个垂直层的等密度线深度谱和等密度线上的θ-S异常沿着分布。在30-46公里波长的等密度线深度方差减少从冬季到春季到夏季的2-10倍的分层区域。通过将盐度异常作为示踪剂，残余混合层中的有效等密扩散率估计为30-46 km波长范围内的1.4 m2 s−1。
[1] We discuss the seasonal evolution of upper-ocean thermohaline structure at small horizontal scales. The upper 350 m of a 1000 km long section in the subtropical North Pacific was observed in winter, spring, and summer with 3–14 km horizontal resolution. Four vertical regions had distinct density and salinity structure: the mixed layer, remnant mixed layer, high-stratification layer, and permanent thermocline. The remnant mixed layer consists of water from the winter mixed layer left over after restratification. The remnant mixed layer was most similar to the mixed layer in winter and spring, and most similar to the high-stratification layer below in summer. The high-stratification layer had elevated stratification that varied seasonally. The permanent thermocline varied little seasonally and was horizontally and vertically uniform in comparison. In all seasons, density ratios showed that mixed-layer θ-S differences tended to compensate in density with the strongest tendency toward compensation in winter. Density ratios were temperature dominated in the remnant mixed layer consistent with salt-fingering. Salinity anomalies were largest at the surface and decayed with depth in all seasons. Spectra of isopycnal depth and θ-S anomalies along isopycnals are compared between the three seasons and four vertical layers. Isopycnal depth variance at 30–46 km wavelengths decreased from winter to spring to summer by a factor of 2–10 in stratified regions. By treating salinity anomalies as a tracer, the effective isopycnal diffusivity in the remnant mixed layer was estimated to be 1.4 m2 s−1 over 30–46 km wavelengths.