Overturning circulation that ventilates the intermediate layer of the Sea of Okhotsk and the North Pacific: The role of salinity advection
Overturning circulation that ventilates the intermediate layer of the Sea of Okhotsk and the North Pacific: The role of salinity advection
复制标题
DOI：
10.1002/2014jc009995
复制
发表时间：
2015-03-01
影响因子：
3.6
通讯作者：
Wakatsuchi, Masaaki
中科院分区：
文献类型：
--
作者：
Matsuda, Junji;Mitsudera, Humio;Wakatsuchi, Masaaki
鄂霍次克海西北大陆架的致密陆棚水（DSW）形成是为北太平洋中间层通风的翻转环流下肢的开始。由鄂霍次克海和亚北极环流的表面流组成的上肢尚未得到澄清。使用高分辨率的北太平洋海洋模式，在鄂霍次克海的曲线网格细至3公里× 3公里，我们成功地代表了翻转环流的三维结构，包括狭窄的边界电流和流过构成上肢的海峡，以及由DSW形成和通风组成的下肢。特别是，路径和时间尺度从白令海到中间层通过在鄂霍次克海的通风进行了详细研究，使用示踪剂实验。此外，我们还发现连接表层和中层的翻转环流对风应力非常敏感。在强风的情况下，在海湾下的沿岸流的DSW形成的加强，因此，从表层到中间层的经向输送增加。在亚北极地区，强风还引起正的海面盐度异常，导致密度分层显著减少和DSW盐度增加（即，密度）。这些过程共同作用，产生强烈的翻转环流和深层通风，如果风很强，甚至可以潜到鄂霍次克海的底部。
Dense Shelf Water (DSW) formation in the northwestern continental shelf of the Sea of Okhotsk is the beginning of the lower limb of the overturning circulation that ventilates the intermediate layer of the North Pacific Ocean. The upper limb consisting of surface currents in the Okhotsk Sea and the subarctic gyre has not been clarified. Using a high-resolution North Pacific Ocean model with a curvilinear grid as fine as 3 km x 3 km in the Sea of Okhotsk, we succeeded in representing the three-dimensional structure of the overturning circulation including the narrow boundary currents and flows through straits that constitute the upper limb, as well as the lower limb consisting of DSW formation and ventilation. In particular, pathways and time scales from the Bering Sea to the intermediate layer via the ventilation in the Sea of Okhotsk were examined in detail using tracer experiments. Further, we found that the overturning circulation that connects the surface and intermediate layer is sensitive to wind stress. In the case of strong winds, the coastal current under polynyas where DSW forms is intensified, and consequently diapycnal transport from the surface layer to the intermediate layer increases. Strong winds also induce a positive sea surface salinity anomaly in the subarctic region, causing a significant decrease in the density stratification and increase in the DSW salinity (i.e., density). These processes act together to produce intense overturning circulation and deep ventilation, which may subduct even to the bottom of the Sea of Okhotsk if the wind is strong.