Collaborative Research: Global Climate Model Simulations of Extreme Cold-Air Outbreaks

这个项目有两个主要目标。首先是确定全球气候模型在模拟寒潮特征方面的能力和局限性。第二是利用气候模式(A)从动力和物理过程方面诊断极端寒冷暴发的可变性，以及(B)作为预测未来冷空气暴发特征(例如，频率、强度、地理分布)在十年至百年时间尺度上变化的基础。这项研究的动机是这样一个事实，即极端事件特征的变化的影响可能至少与气候平均的相关变化一样重要，其中寒冷的爆发是最主要的例子。该项目将利用一套最先进的全球气候模型，包括国家大气研究中心(NCAR)社区气候系统模型的几个版本，以及国家环境预测中心(NCEP)/NCAR全球再分析。PI将检验几个假设：1)。这种提高的分辨率使得能够更成功地模拟有时发生在北美的浅层寒冷爆发；2)。动力和热力学过程对于极端冷空气爆发进入中纬度是重要和必要的；3)。在温室强迫下，未来冷爆发的变化将至少由大尺度环流的变化和热力学变暖决定。最后，这项研究将寻求确定欧亚冷爆发在当前和温室模拟中与北美的不同之处。更广泛的影响将通过两个预期结果实现：(1)基于前期气压和海洋温度条件的冷爆发可操作中长期可预测性的改善，以及(2)首次评估温室强迫气候中未来冷爆发的行为。能够预测冷空气爆发的频率和/或强度的变化可以对规划和政策产生重大和有益的影响。其他更广泛的影响将是将研究成果纳入伊利诺伊大学和贝洛伊特学院的本科教学；纳入入门级本科教科书的第二版；以及纳入关于极端寒冷爆发的公众可访问网站。

This project has two primary objectives. The first is a determination of the capabilities and limitations of global climate models with respect to their simulation of cold wave characteristics. The second is the use of climate models (a) for the diagnosis of the variability of extreme cold outbreaks in terms of dynamical and physical processes and (b) as a basis for projecting future changes in the characteristics (e.g., frequency, intensity, geographical distribution) of cold air outbreaks over the decade-to-century timescale. The research is motivated by the fact that the impacts of changes in the characteristics of extreme events, of which cold outbreaks are prime examples, are likely to be at least as important as associated changes of climatic averages. The project will utilize a suite of state-of-the-art global climate models, including several versions of the National Center for Atmospheric Research's (NCAR) Community Climate System Model, as well as the National Centers for Environmental Prediction (NCEP)/NCAR global reanalysis. The PIs will test several hypotheses:1). That enhanced resolution permits more successful simulations of the shallow cold outbreaks that sometimes occur over North America;2). That both dynamic and thermodynamic processes are important and necessary for the penetration of extreme cold-air outbreaks into middle latitudes;3). That future changes of cold outbreaks under greenhouse forcing will be determined at least as much by changes in the large-scale circulation as by thermodynamic warming.Finally, the research will seek to determine how Eurasian cold outbreaks differ from those in North America, in both present-day and greenhouse simulations.Broader impacts will be achieved through two expected outcomes: (1) improvement in operational medium- and long-range predictability of cold outbreaks based on antecedent pressure and ocean temperature conditions, and (2) the first assessment of the future behavior of cold outbreaks in a greenhouse-forced climate. The ability to anticipate shifts in the frequencies and/or intensities of cold air outbreaks can have large and beneficial impacts on planning and policy. Additional broader impacts will be the incorporation of the research results: into undergraduate teaching at both the University of Illinois and Beloit College; into a second edition of an introductory-level undergraduate textbook; and into a publicly accessible website on extreme cold outbreaks.