Elevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension
Elevated turbulent and double-diffusive nutrient flux in the Kuroshio over the Izu Ridge and in the Kuroshio Extension
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DOI：
10.1007/s10872-020-00582-2
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发表时间：
2021-01
影响因子：
2.3
通讯作者：
T. Nagai;Gandy Maria Rosales Quintana;Gloria Silvana Durán Gómez;F. Hashihama;K. Komatsu
中科院分区：
文献类型：
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作者：
T. Nagai;Gandy Maria Rosales Quintana;Gloria Silvana Durán Gómez;F. Hashihama;K. Komatsu
虽然众所周知，黑潮是一个营养流，因为这些营养物质位于黑暗的次表层，除非它们被提供给阳光照射的表层，否则它们不会立即用于光合作用。最近的微结构观测表明，黑潮在地形地貌上的流动和次表层的双重扩散导致了强烈的昼夜混合。然而，目前还不清楚这些微尺度混合过程能提供多少营养通量。在这项研究中，利用自主微结构浮标和营养盐采样，量化了伊豆海脊黑潮引起的营养盐通量和黑潮延伸区的双重扩散引起的营养盐通量。据估计，硝酸盐扩散通量在伊豆海脊附近20-30公里的距离上，并沿着黑潮向下游方向延伸超过100公里，增加了下游200公里区域的次表层叶绿素a浓度。双扩散引起的硝酸盐通量估计为黑潮延伸区的1个，这表明，这种双重扩散引起的次表层营养盐通量是否最终能够对表层初级生产做出贡献取决于额外的涡旋向上和向北的通量。
While the Kuroshio is known to be a nutrient stream, as these nutrients are in dark subsurface layers, they are not immediately available for photosynthesis unless they are supplied to the sunlit surface layers. Recent microstructure observations have revealed that strong diapycnal mixing caused by the Kuroshio flowing over topographic features and double diffusion in the subsurface layers of the Kuroshio. However, it is still unclear how much nutrient flux can be provided by these microscale mixing processes. In this study, using an autonomous microstructure float and nutrient samplings, nutrient flux caused by the Kuroshio over the Izu Ridge, and that caused by double diffusion in the Kuroshio Extension are quantified. The nitrate diffusive flux is estimated to beover a distance, 20–30 km near the Izu Ridge and, which persists further downstream direction over 100 km along the Kuroshio, increasing the subsurface chlorophyll-a concentration in the region 200 km downstream. The double-diffusion-induced nitrate flux is estimated to be 1-in the pycnostad 26–of the Kuroshio Extension, suggesting that whether this double-diffusion-induced nutrient flux in the subsurface layers can ultimately contribute to surface primary production depends on additional eddy up- and northward fluxes.