Climate models are important tools for investigating how the climate might change in the future, however recent observations have suggested that these models are unable to capture the overturning in subpolar North Atlantic correctly, casting doubt on their projections of the Atlantic Meridional Overturning Circulation (AMOC). Here we compare the overturning and surface water mass transformation in a set of CMIP6 models with observational estimates. There is generally a good agreement, particularly in the recent conclusion from observations that the mean overturning in the east (particularly in the Iceland and Irminger seas) is stronger than that in the Labrador Sea. The overturning in the Labrador Sea is mostly found to be small, but has a strong relationship with salinity: fresh models have weak overturning and saline models have stronger mean overturning and stronger relationships of the Labrador Sea overturning variability with the AMOC further south.We also find that the overturning reconstructed from surface flux driven water mass transformation is a good indicator of the actual overturning, though mixing can modify variability and shift signals to different density classes.

气候模型是研究未来气候可能如何变化的重要工具，但最近的观察表明，这些模型无法正确捕捉副极地北大西洋的倾覆，从而对其对大西洋经向倾覆环流 (AMOC) 的预测产生怀疑. 在这里，我们将一组 CMIP6 模型中的倾覆和地表水质量转换与观测估计值进行比较。总体上达成了很好的一致，特别是最近从观测得出的结论中，即​​东部（特别是冰岛和伊尔明格海）的平均倾覆比拉布拉多海强。拉布拉多海的倾覆大多被发现很小，但与盐度有很强的关系：