Zhang Weiwei, Yan Xiao-Hai
State Key Laboratory of Marine Environmental Science, Xiamen University, Xiamen, 361005, China.
College of Earth, Ocean, and Environment, Newark, United States.
Sci Rep. 2017 Oct 23;7(1):13748. doi: 10.1038/s41598-017-14158-6.
The Subpolar North Atlantic (SPNA) is one of the most important areas to global climate because its ocean heat content (OHC) is highly correlated with the Atlantic Meridional Overturning Circulation (AMOC), and its circulation strength affects the salt transport by the AMOC, which in turn feeds and sustains the strength of the AMOC. Moreover, the recent global surface warming "hiatus" may be attributed to the SPNA as one of the major planetary heat sinks. Although almost synchronized before 1996, the OHC has greater spatial disparities afterwards, which cannot be explained as driven by the North Atlantic Oscillation (NAO). Temperature decomposition reveals that the western SPNA OHC is mainly determined by the along isopycnal changes, while in the eastern SPNA along isopycnal changes and isopycnal undulation are both important. Further analysis indicates that heat flux dominates the western SPNA OHC, but in the eastern SPNA wind forcing affects the OHC significantly. It is worth noting that the along isopycnal OHC changes can also induce heaving, thus the observed heaving domination in global oceans cannot mask the extra heat in the ocean during the recent "hiatus".
副极地北大西洋（SPNA）是对全球气候最重要的区域之一，因为其海洋热含量（OHC）与大西洋经向翻转环流（AMOC）高度相关，并且其环流强度影响AMOC的盐分输送，进而为AMOC的强度提供支撑并维持其强度。此外，近期全球表面变暖的“停滞期”可能归因于SPNA，它是主要的全球热汇之一。尽管1996年之前OHC几乎同步变化，但之后其空间差异增大，这无法用北大西洋涛动（NAO）来解释。温度分解表明，SPNA西部的OHC主要由沿等密度面的变化决定，而在SPNA东部，沿等密度面的变化和等密度面波动都很重要。进一步分析表明，热通量主导着SPNA西部的OHC，但在SPNA东部，风应力对OHC有显著影响。值得注意的是，沿等密度面的OHC变化也会引发垂向位移，因此在全球海洋中观测到的垂向位移主导现象并不能掩盖近期“停滞期”海洋中额外的热量。
