Toward the credibility of Northeast United States summer precipitation projections in CMIP5 and NARCCAP simulations
Toward the credibility of Northeast United States summer precipitation projections in CMIP5 and NARCCAP simulations
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提高 CMIP5 和 NARCCAP 模拟中美国东北部夏季降水预测的可信度
DOI：
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发表时间：
2015
期刊：
影响因子：
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通讯作者：
A. Seth
中科院分区：
文献类型：
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作者：
J. Thibeault;A. Seth
美国东北部和附近的加拿大（东北部）的降水预测15个第五阶段的耦合模式相互比较项目（CMIP 5）模式进行了检查。一个基于过程的评估与潮湿的东北夏季的大气环流特征进行检查是否可信度可以区分内的多模式集合。基于这些评估，以及对区域平均降水的年际统计特性的分析，形成了模型子集。将每个子集的多模式降水预测与所有模式的多模式预测进行比较。高分辨率北美区域气候变化评估计划（NARCCAP）区域气候模式（RCM）也进行了类似的评估，分组为子集，并检查未来的预测。CMIP 5模式充分模拟了与东北部潮湿夏季相关的大尺度环流特征，尽管在模拟热带大西洋西部/墨西哥湾观测到的海平面气压和水汽辐散异常时都有误差。RCMs模拟的相关大尺度过程类似于其驱动全球气候模式（GCMs），但并不总是现实的。未来的RCM研究可以受益于过程分析的潜在驱动GCM动态降尺度之前。没有CMIP 5或NARCCAP模型被确定为明显更可信，但六个GCM和四个RCM表现一贯更好。在“Better”模式中，对未来夏季降水变化方向的预测并不一致。CMIP 5预测表明，东北降水响应取决于北大西洋反气旋的动力学和相关的环流和水分辐合模式，这是不同的“更好”的模型。即使当模型的可信度不能明确区分，模拟过程的检查提供了重要的见解，其演变下温室效应变暖。
Precipitation projections for the northeast United States and nearby Canada (Northeast) are examined for 15 Fifth Phase of the Coupled Model Intercomparison Project (CMIP5) models. A process‐based evaluation of atmospheric circulation features associated with wet Northeast summers is performed to examine whether credibility can be differentiated within the multimodel ensemble. Based on these evaluations, and an analysis of the interannual statistical properties of area‐averaged precipitation, model subsets were formed. Multimodel precipitation projections from each subset were compared to the multimodel projection from all of the models. Higher‐resolution North American Regional Climate Change Assessment Program (NARCCAP) regional climate models (RCMs) were subjected to a similar evaluation, grouping into subsets, and examination of future projections. CMIP5 models adequately simulate most large‐scale circulation features associated with wet Northeast summers, though all have errors in simulating observed sea level pressure and moisture divergence anomalies in the western tropical Atlantic/Gulf of Mexico. Relevant large‐scale processes simulated by the RCMs resemble those of their driving global climate models (GCMs), which are not always realistic. Future RCM studies could benefit from a process analysis of potential driving GCMs prior to dynamical downscaling. No CMIP5 or NARCCAP models were identified as clearly more credible, but six GCMs and four RCMs performed consistently better. Among the “Better” models, there is no consistency in the direction of future summer precipitation change. CMIP5 projections suggest that the Northeast precipitation response depends on the dynamics of the North Atlantic anticyclone and associated circulation and moisture convergence patterns, which vary among “Better” models. Even when model credibility cannot be clearly differentiated, examination of simulated processes provides important insights into their evolution under greenhouse warming.