El Nino vertical mixing enhancement under the winter mixed layer at western subarctic North Pacific station K2
El Nino vertical mixing enhancement under the winter mixed layer at western subarctic North Pacific station K2
复制标题
西亚北极北太平洋站K2冬季混合层下的厄尔尼诺垂直混合增强
DOI：
10.1029/2020jc016913
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发表时间：
2021
期刊：
影响因子：
--
通讯作者：
Hiroshi Uchida
中科院分区：
文献类型：
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作者：
Akira Nagano;Masahide Wakita;Tetsuichi Fujiki;Hiroshi Uchida
2015年7月至2019年6月，我们通过在K2站（N，E）部署系泊浮标，在上层海洋进行了流速和水文时间序列观测，以了解影响西亚北极北太平洋冬季混合层（ML）水酸化的物理条件。与2015/2016年和2018/2019年厄尔尼诺事件无关的风变化激发了具有显著流速切变的扰动。在冬季，特别是厄尔尼诺年，ML下面的密度分层也减弱了。基于体Richardson数混合方案，我们发现厄尔尼诺相关的流速切变的加强增强了由近惯性流速变化驱动的冬季ML下方的垂直扩散率。密度层结的减弱对垂直扩散系数的增强是无效的。这表明，厄尔尼诺相关的大垂直混合通过增强富含溶解无机碳的深水的夹带加速了冬季ML水的酸化。
We conducted a current velocity and hydrographic time series observation in the upper ocean by deploying a mooring buoy at station K2 (N, E) from July 2015 to June 2019 to understand the physical conditions that affect the acidification of the winter mixed layer (ML) water in the western subarctic North Pacific. Disturbances with substantial current velocity shear were excited by the wind changes remotely related to the 2015/2016 and 2018/2019 El Niño events. The density stratification beneath the ML was also weakened in winter, particularly the El Niño years. Based on the bulk Richardson number mixing scheme, we found that the El Niño‐related strengthening of the current velocity shear enhanced the vertical diffusivity beneath the winter ML driven by the near‐inertial current velocity variation. The weakening of the density stratification is ineffective in enhancing the vertical diffusivity. It is suggested that the El Niño‐related large vertical mixing accelerates the acidification of the winter ML water through the enhancement of the entrainment of the deep water that is rich in dissolved inorganic carbon.