Representation of the boreal summer tropical Atlantic–western North Pacific teleconnection in AGCMs: comparison of CMIP5 and CMIP6
Representation of the boreal summer tropical Atlantic–western North Pacific teleconnection in AGCMs: comparison of CMIP5 and CMIP6
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DOI：
10.1007/s00382-020-05427-8
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发表时间：
2020-08
期刊：
影响因子：
4.6
通讯作者：
Jinqing Zuo;Chenghu Sun;Weijing Li;Jiejing Wu;Hongli Ren
中科院分区：
文献类型：
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作者：
Jinqing Zuo;Chenghu Sun;Weijing Li;Jiejing Wu;Hongli Ren
以往的研究表明，夏季北方热带大西洋（NTA）暖（冷）海表温度（SST）异常可增强（减弱）西北太平洋（WNP）异常低层反气旋。本研究评估目前的大气环流模式（AGCMs）模拟这样一个NTA-WNP连接的能力，通过使用大气模式相互比较项目实验从23耦合模式相互比较项目第5阶段（CMIP 5）和35 CMIP 6气候模式。结果表明，CMIP 5和CMIP 6多模式集合（MME）的平均值和大多数的个人AGCM可以合理地再现所观察到的模式的NTA相关的异常反气旋在西北太平洋北部夏季。总体而言，CMIP 6 AGCM在表示NTA-WNP连接方面的性能与CMIP 5 AGCM相似，只是前者在模型之间的分布往往比后者小。此外，CMIP 5和CMIP 6 MME平均值以及各个模型都可以合理地代表负责北方夏季NTA-WNP连接的机制，该机制涉及太平洋-大西洋上空的纬向西延伸翻转环流。此外，与NTA相关的WNP异常反气旋的强度与CMIP 5和CMIP 6 AGCM的WNP局地气候对流活动的强度呈正相关，这意味着更好地代表WNP气候对流活动可能是提高AGCM模拟北方夏季NTA-WNP连接的技能的关键。然而，模式偏差在模拟的气候对流活动的WNP仍然很大，目前的CMIP 6 AGCMs，虽然偏差减少了大部分的热带和亚热带太平洋-大西洋地区相比，CMIP 5 AGCMs在北方夏季。
Previous studies have revealed that warm (cold) sea surface temperature (SST) anomalies in the northern tropical Atlantic (NTA) can enhance (weaken) the anomalous low-level anticyclone over the western North Pacific (WNP) during boreal summer. This study assesses the ability of current atmospheric general circulation models (AGCMs) to simulate such an NTA–WNP connection by using Atmospheric Model Intercomparison Project experiments from 23 Coupled Model Intercomparison Project Phase 5 (CMIP5) and 35 CMIP6 climate models. It is shown that both the CMIP5 and CMIP6 multimodel ensemble (MME) averages and the majority of the individual AGCMs can reasonably reproduce the observed pattern of the NTA-related anomalous anticyclone over the WNP during boreal summer. Overall, the performance of the CMIP6 AGCMs in representing the NTA–WNP connection is similar to that of the CMIP5 AGCMs, except that the former tends to have a smaller spread than the latter among models. Additionally, both the CMIP5 and CMIP6 MME averages as well as the individual models can reasonably represent the mechanism responsible for the boreal summer NTA–WNP connection, which involves a zonally westward-extending overturning circulation over the Pacific–Atlantic Oceans. Furthermore, the intensity of the NTA-related WNP anomalous anticyclone is positively correlated with that of the WNP local climatological convection activity for both the CMIP5 and CMIP6 AGCMs, implying that better representation of the WNP climatological convection activity may be crucial for improving the skill of AGCMs to simulate the boreal summer NTA–WNP connection. However, model bias in the simulation of climatological convection activity over the WNP remains large for the current CMIP6 AGCMs, although the bias is reduced over most of the tropical and subtropical Pacific–Atlantic regions compared to that for the CMIP5 AGCMs during boreal summer.