Submesoscale transition from geostrophic flows to internal waves in the northwestern Pacific upper ocean.
Submesoscale transition from geostrophic flows to internal waves in the northwestern Pacific upper ocean.
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DOI：
10.1038/ncomms14055
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发表时间：
2017-01-09
影响因子：
16.6
通讯作者：
Klein P
中科院分区：
文献类型：
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作者：
Qiu B;Nakano T;Chen S;Klein P
利用雷达干涉测量技术，下一代地表水和海洋地形卫星使命将把测得的海面高度分辨率提高到15公里，使我们能够首次在次中尺度范围内调查全球上层海洋的变化。本文通过分析2004-2016年西北太平洋沿着137°E的船载声学多普勒海流剖面仪测量数据，发现观测到的上层海洋流速由平衡的地转流和不平衡的内波组成。过渡长度尺度，Lt，分离这两个议案，被发现强烈依赖于当地中尺度涡变的能量水平。在黑潮涡旋丰富的西边界流区，Lt可小于15 km，而在相对稳定的北赤道流路径上，Lt可大于沿着200 km。正确地分离地转波和内波信号对地表水和海洋地形使命来说既是一个挑战也是一个机会。卫星高度计的分辨率很难捕捉到海洋上层的中尺度信号。在这里，作者分析了船载声学多普勒海流剖面仪测量西北太平洋，并表明，平衡的地转流和不平衡的内波包括上层海洋速度。
With radar interferometry, the next-generation Surface Water and Ocean Topography satellite mission will improve the measured sea surface height resolution down to 15 km, allowing us to investigate for the first time the global upper ocean variability at the submesoscale range. Here, by analysing shipboard Acoustic Doppler Current Profiler measurements along 137°E in the northwest Pacific of 2004–2016, we show that the observed upper ocean velocities are comprised of balanced geostrophic flows and unbalanced internal waves. The transition length scale, Lt, separating these two motions, is found to depend strongly on the energy level of local mesoscale eddy variability. In the eddy-abundant western boundary current region of Kuroshio, Lt can be shorter than 15 km, whereas Lt exceeds 200 km along the path of relatively stable North Equatorial Current. Judicious separation between the geostrophic and internal wave signals represents both a challenge and an opportunity for the Surface Water and Ocean Topography mission. Satellite altimeters resolution poorly capture mesoscale signals in the upper ocean. Here, the authors analyse shipboard Acoustic Doppler Current Profiler measurements from the northwest Pacific, and show that balanced geostrophic flows and unbalanced internal waves comprise upper ocean velocities.