Variability of the Pacific subtropical cells under global warming in CMIP6 models
Variability of the Pacific subtropical cells under global warming in CMIP6 models
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DOI：
10.1007/s00343-023-2315-2
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发表时间：
2023-09
影响因子：
1.6
通讯作者：
Xue Han;Junqiao Feng;Yunlong Lu;D. Hu
中科院分区：
文献类型：
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作者：
Xue Han;Junqiao Feng;Yunlong Lu;D. Hu
太平洋副热带环流圈（STC）是连接热带和副热带的浅层纬向翻转环流，被认为是热带太平洋年代际变化的重要驱动力。利用耦合模式相互比较项目（CMIP 6）最新阶段的多模态输出和海洋再分析产品，研究了全球变暖下STC的变化。首先，体积输送诊断分析，以评估如何耦合模式和海洋再分析产品再现内部STC输送。还分析了高排放增暖情景下大气内部STC热输送的变化。结果表明，全球变暖条件下，沿着9°S和9°N的STC输送的多模态平均线性趋势分别为-0.02 Sv/a和0.04 Sv/a，这主要是由于上层海洋层结加强和风场减弱的共同作用。在未来的气候中，内陆STC与西部边界输送之间存在补偿关系，且9°S的补偿关系比9°N的补偿关系更显著。此外，与海洋再分析产品相比，耦合模式往往低估了STC内部输送辐合的变化，从而可能损失了部分海表温度（SST）驱动力，这可能是模式模拟的STC与SST相关性较低的原因。未来情景模拟结果表明，在全球变暖的影响下，STC内部的热输送减弱，各模式的结果基本一致。
The Pacific subtropical cells (STCs) are shallow meridional overturning circulations connecting the tropics and subtropics, and are assumed to be an important driver of the tropical Pacific decadal variability. The variability of STCs under global warming is investigated using multimodal outputs from the latest phase of the Coupled Model Inter-comparison Project (CMIP6) and ocean reanalysis products. Firstly, the volume transport diagnostic analysis is employed to evaluate how coupled models and ocean reanalysis products reproduce interior STC transport. The variation of heat transport by the interior STC under the high-emissions warming scenarios is also analyzed. The results show that the multimodal-mean linear trends of the interior STC transport along 9°S and 9°N are −0.02 Sv/a and 0.04 Sv/a under global warming, respectively, which is mainly due to the combined effect of the strengthened upper oceanic stratification and the weakening of wind field. There is a compensation relationship between the interior STC and the western boundary transport in the future climate, and the compensation relationship of 9°S is more significant than that of 9°N. In addition, compared with ocean reanalysis products, the coupled models tend to underestimate the variability of the interior STC transport convergence, and thus may lose some sea surface temperature (SST) driving force, which may be the reason for the low STC-SST correlation simulated by the model. The future scenario simulation shows that the heat transport of interior STC is weakened under global warming, with a general agreement across models.