Role of the mean state for the Southern Hemispheric jet stream response to CO2forcing in CMIP6 models
Role of the mean state for the Southern Hemispheric jet stream response to CO2forcing in CMIP6 models
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DOI：
10.1088/1748-9326/ab8331
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发表时间：
2020-06-01
影响因子：
6.7
通讯作者：
Zappa, Giuseppe
中科院分区：
文献类型：
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作者：
Curtis, Paul Edwin;Ceppi, Paulo;Zappa, Giuseppe
全球气候模型表明，南半球（SH）急流因CO（2）强迫而向极地移动，但这种移动的幅度仍然高度不确定。在这里，我们在耦合模型比对项目第 6 阶段 (CMIP6) 模拟中分析了 SH 急流对 4xCO(2) 强迫的响应，并发现与 CMIP5 相比，冬季急流变化明显减弱。我们认为，这种柔和的响应是由于平均喷流位置更偏向极地造成的，这与喷流位置相对于 1980-2004 年重新分析的偏差大大减少是一致的。改进的平均射流位置不能用模拟海面温度的变化来解释。相反，我们发现有迹象表明，相对于 CMIP5，CMIP6 中水平网格分辨率的增加有助于提高平均喷流纬度，从而减少 CO(2) 强迫下的喷流偏移。这些结果意味着 CMIP6 模型可以提供更现实的 SH 气候变化预测。
Global climate models indicate that the Southern Hemispheric (SH) jet stream shifts poleward in response to CO(2)forcing, but the magnitude of this shift remains highly uncertain. Here we analyse the SH jet stream response to 4xCO(2)forcing in Coupled Model Intercomparison Project phase 6 (CMIP6) simulations, and find a substantially muted jet shift during winter compared with CMIP5. We suggest this muted response results from a more poleward mean jet position, consistent with a strongly reduced bias in jet position relative to the reanalysis during 1980-2004. The improved mean jet position cannot be explained by changes in the simulated sea surface temperatures. Instead, we find indications that increased horizontal grid resolution in CMIP6 relative to CMIP5 has contributed to the higher mean jet latitude, and thus to the reduced jet shift under CO(2)forcing. These results imply that CMIP6 models can provide more realistic projections of SH climate change.