Spatial variations in the Kuroshio nutrient transport from the East China Sea to south of Japan
Spatial variations in the Kuroshio nutrient transport from the East China Sea to south of Japan
复制标题
东海至日本南部黑潮营养盐输送的空间变化
DOI：
10.5194/bg-10-6403-2013
复制
发表时间：
2013-01-01
期刊：
影响因子：
4.9
通讯作者：
Huang, D. J.
中科院分区：
文献类型：
--
作者：
Guo, X. Y.;Zhu, X. -H.;Huang, D. J.
根据使用2000年至2009年39次航行的重复水文数据计算的绝对地转速度和1964年至2009年在同一地区测量的硝酸盐浓度，我们得到了时间平均的硝酸盐通量（流速和硝酸盐浓度的乘积）和硝酸盐输运本文对从东海（PN和TK断面）到日本南部（ASUKA和137 E断面）的黑潮四个断面的通量积分进行了研究。此外，我们还考察了琉球群岛以东的OK断面，以了解琉球海流对日本以南黑潮营养盐输送的贡献。平均硝酸盐通量显示了一个地下最大核，PN、TK、ASUKA、137 E和OK剖面的数值分别为9.6、10.6、11.2、10.5和5.7 mol m −2 s −1。地下最大岩心深度在这五个剖面之间变化，在剖面PN、TK、ASUKA、137 E和OK处分别约为400、500、500、400和800 m。在PN、TK、ASUKA、137 E和OK断面，硝酸盐的平均下游输送量分别为204.8、165.8、879.3、1230.4和338.6 kmol s −1。营养盐在这些断面的输送表明，黑潮营养流的存在，从其上游到下游地区。琉球海流（OK断面）的深层流结构对硝酸盐输运的贡献与东海黑潮（TK断面）至日本以南地区的输运顺序相同，但前者的输运量仅为后者的五分之一。计算结果表明，硝酸盐沿着黑潮向下游输送量的增加主要是由于硝酸盐向黑潮的再循环。然而，这一结论取决于水深。在上层（θ）中，沿着黑潮的NO3-浓度向下游的变化以及NO3-再循环引起的NO3-浓度向下游的变化对NO3-沿着黑潮向下游输送的增加有显著的贡献。在深层（> 26.5σ θ），NO3-浓度变化较小，黑潮环流控制了NO3-向下游输送的增加。
Based on absolute geostrophic velocity, which was calculated using repeated hydrographic data of 39 cruises from 2000 to 2009 and nitrate concentrations measured in the same areas from 1964 to 2009, we obtained the temporally averaged nitrate flux (the product of velocity and nitrate concentration) and nitrate transport (integration of flux over one section) of four sections across the Kuroshio from the East China Sea (sections PN and TK) to an area south of Japan (sections ASUKA and 137E). In addition, we examined section OK east of the Ryukyu Islands in order to understand how the Ryukyu Current contributes to the transport of nutrients by the Kuroshio south of Japan. The mean nitrate flux shows a subsurface maximum core with values of 9.6, 10.6, 11.2, 10.5, and 5.7 mol m −2 s −1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The depth of the subsurface maximum core changes among these five sections and is approximately 400, 500, 500, 400, and 800 m at sections PN, TK, ASUKA, 137E, and OK, respectively. The mean downstream nitrate transport is 204.8, 165.8, 879.3, 1230.4, and 338.6 kmol s −1 at sections PN, TK, ASUKA, 137E, and OK, respectively. The transport of nutrients in these sections suggests the presence of the Kuroshio nutrient stream from its upstream to downstream regions. The deep current structure of the Ryukyu Current (section OK) contributes to the same order of nitrate transport as does the Kuroshio from the East China Sea (section TK) to the area south of Japan; however, the former only has one-fifth the volume transport of the latter. A budget calculation suggests that the downstream increase of transported nitrate along the Kuroshio is mainly caused by the recirculation of nitrate into the Kuroshio. This conclusion, however, depends on water depth. In the upper layers ( θ ), the downstream change of nitrate concentration along the Kuroshio and that from the recirculation of nitrate has a significant contribution to the downstream increase of nitrate transport along the Kuroshio. In the deep layers (> 26.5σ θ ), the change in nitrate concentration is small and the Kuroshio recirculation dominates the downstream increase of nitrate transport.