CMIP5 Diversity in Southern Westerly Jet Projections Related to Historical Sea Ice Area: Strong Link to Strengthening and Weak Link to Shift
CMIP5 Diversity in Southern Westerly Jet Projections Related to Historical Sea Ice Area: Strong Link to Strengthening and Weak Link to Shift
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DOI：
10.1175/jcli-d-17-0320.1
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发表时间：
2018-01-01
影响因子：
4.9
通讯作者：
Holmes, Caroline R.
中科院分区：
文献类型：
--
作者：
Bracegirdle, Thomas J.;Hyder, Patrick;Holmes, Caroline R.
在温室气体浓度增加的未来情景下，南半球气候预计变化的一个主要特征是中纬度近地面西风（西风急流）的主要涡动带向极移动和加强。然而，在不同的气候模式中，预测的21世纪世纪西风急流变化存在很大的不确定性。在这里，对世界气候研究方案耦合模式相互比较项目第5阶段的模式进行了评价，以评估模拟海冰面积多样性、南极扩增和代表性浓度路径8.5情景下西风急流预计在世纪变化中的多样性之间的联系。为了帮助理清耦合模式分析中的因果关系，还对CMIP 5中的非耦合大气固定海面试验进行了评价。结果表明，在所有的季节，预计RCP 8.5喷流加强的方差约有一半的统计解释模拟历史SIA的模型间差异，其中CMIP 5模型具有较大的基线SIA表现出更多的冰撤退和喷流加强在未来。然而，与喷气式飞机转移的联系要弱得多，只有在南方的秋季和冬季才有统计学意义。有人建议，一个显着的跨模式之间的相关性，历史喷流强度和预计的强度变化（r=-0.58），至少部分是由于大气驱动的历史SIA偏差，然后反馈到大气中，在未来的预测。结果强调，SIA出现在近端的海表温度梯度的变化，在西风急流预测模型的多样性一致行动。
A major feature of projected changes in Southern Hemisphere climate under future scenarios of increased greenhouse gas concentrations is the poleward shift and strengthening of the main eddy-driven belt of midlatitude, near-surface westerly winds (the westerly jet). However, there is large uncertainty in projected twenty-first-century westerly jet changes across different climate models. Here models from the World Climate Research Programme's phase 5 of the Coupled Model Intercomparison Project (CMIP5) were evaluated to assess linkages between diversity in simulated sea ice area (SIA), Antarctic amplification, and diversity in projected twenty-first-century changes in the westerly jet following the representative concentration pathway 8.5 (RCP8.5) scenario. To help disentangle cause and effect in the coupled model analysis, uncoupled atmosphere-only fixed sea surface experiments from CMIP5 were also evaluated. It is shown that across all seasons, approximately half of the variance in projected RCP8.5 jet strengthening is explained statistically by intermodel differences in simulated historical SIA, whereby CMIP5 models with larger baseline SIA exhibit more ice retreat and less jet strengthening in the future. However, links to jet shift are much weaker and are only statistically significant in austral autumn and winter. It is suggested that a significant cross-model correlation between historical jet strength and projected strength change (r=-0.58) is, at least in part, a result of atmospherically driven historical SIA biases, which then feed back into the atmosphere in future projections. The results emphasize that SIA appears to act in concert with proximal changes in sea surface temperature gradients in relation to model diversity in westerly jet projections.