CMIP5 Projection of Significant Reduction in Extratropical Cyclone Activity over North America
CMIP5 Projection of Significant Reduction in Extratropical Cyclone Activity over North America
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DOI：
10.1175/jcli-d-13-00209.1
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发表时间：
2013-12-01
影响因子：
4.9
通讯作者：
Chang, Edmund K. M.
中科院分区：
文献类型：
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作者：
Chang, Edmund K. M.
美国大陆和加拿大南部的风暴路径变化的预测由23个模型从第5阶段的耦合模式相互比较项目（CMIP 5）进行了比较，预测的变化由11个模型从第3阶段的CMIP（CMIP 3）。总体而言，在代表性浓度路径8.5（RCP8.5）强迫下，CMIP5模型预测北美风暴路径活动的减少比排放情景特别报告（SRES）A2情景下的CMIP3模型更显着，夏季减少最大，春季减少最小。在时间方差和气旋统计数据方面都发现了这种减少，预计冬季，春季，夏季和秋季的强气旋频率分别减少15.9%，6.6%，32.6%和16.9%。有一个强烈的共识，在23个模型之间的预测变化的迹象，与不到20%的模型预测的变化相反的迹象，在任何风暴路径参数检查。尽管如此，在预测的变化幅度上，模式与模式之间也存在着显著的差异。在34个CMIP5和CMIP3模式的集合中，发现预测风暴路径变化的模式间差异与预测本地定义的平均可用势能（MAPE）变化的模式间差异显着相关，这表明，当地MAPE预测变化的差异不仅可以部分解释模型对模型差异，以及CMIP5和CMIP3预测之间的差异。对预测降水变化的研究表明，预测北美风暴活动减少幅度较大的模型也预测了亚热带降水减少的进一步北侵。
Projections of storm-track changes over the continental United States and southern Canada made by 23 models from phase 5 of the Coupled Model Intercomparison Project (CMIP5) have been compared to changes projected by 11 models from phase 3 of CMIP (CMIP3). Overall, under representative concentration pathway 8.5 (RCP8.5) forcing, CMIP5 models project much more significant decreases in North American storm-track activity than CMIP3 models under the Special Report on Emission Scenarios (SRES) A2 scenario, with the largest decrease in summer and the smallest decrease in spring. The decrease is found both in temporal variance and cyclone statistics, with the frequency of strong cyclones projected to decrease by 15.9%, 6.6%, 32.6%, and 16.9% for winter, spring, summer, and fall, respectively. There is a strong consensus among the 23 models regarding the sign of the projected change, with less than 20% of the models projecting changes in the opposite sign in any of the storm-track parameters examined. Nevertheless, there are also significant model-to-model differences in the magnitude of the projected changes.Projected changes in mean flow baroclinicity have also been examined. Model-to-model differences in the projected storm-track change are found to correlate significantly with model-to-model differences in the projected change in a locally defined mean available potential energy (MAPE) across the ensemble of 34 CMIP5 and CMIP3 models, suggesting that the differences in the projected change in local MAPE can partly account for not only the model-to-model differences but also the differences between CMIP5 and CMIP3 projections. Examination of projected precipitation change suggests that models projecting larger decrease in North American storm-track activity also project a farther northward intrusion of the decrease in subtropical precipitation.