P2C2: Reconstruction and Dynamics of Interhemispheric Hydroclimate Variability between the Americas

该项目的总体目标是利用树木年轮记录编制一份泛太平洋干旱地图集。这项研究的具体目的是探索：1)整个美洲的干旱发生和动态；2)十年至百年一遇的水文气候变率的半球间制度；3)极端事件的大尺度足迹和时间特性(包括对火山活动、太阳强迫和内部变率的反应)；和4)过去的水文气候干旱事件，参照其根本动态，从而深入了解上一个千年中一些最具破坏性的气候事件。将分析水气候模式的相关动态，并诊断其与大规模多变模式和/或强迫变化模式的联系。将对数十年来的水文气候异常(如特大旱灾或暴雨)进行评估，以确定它们是源于具有跨大洲连贯性的半球间气候制度，还是更多是局部的大陆尺度现象。同样，将评估个别年份的极端事件的动态起源和发生概率。为什么要进行这项研究？描述和了解上个千年期间的大范围水气候变异性，是评估和改进对未来水气候变化预测的重要手段。为什么现在要进行这项研究？最近的两项进展使得在这一研究领域取得重大进展的时机已经成熟。首先，对上个千年水文气候变异性的全太平洋重建现已触手可及。第二，利用完全耦合的气候模型对过去千年的模拟进行大量且不断增加的集合，使对过去的水文气候变化进行动态调查成为可能，从而可能改进对预测的未来风险和影响的评估。该项目将有助于增进对极端气候事件和气候变化的了解，包括利用与阿根廷和智利的南美同事的国际合作，创建一份方便用户的干旱地图集，以及关于科学和教育的公共宣传。

The general goal of this project is to develop a pan-Pacific drought atlas using tree-ring records. This research specifically aims to explore: 1) drought occurrences and dynamics across the Americas; 2) inter-hemispheric regimes of decadal-to-centennial hydroclimate variability; 3) large-scale footprints and temporal properties of extreme events (including responses to volcanism, solar forcing and internal variability); and 4) past hydroclimatic drought events in reference to their underlying dynamics thereby offering insight into some of the most disruptive climatic events of the last millennium. Hydroclimate patterns will be analyzed for their associated dynamics and diagnosed for their connection to large-scale modes of variability and/or forced patterns of change. Multidecadal hydroclimate anomalies (e.g. megadroughts or pluvials) will be evaluated to determine if they arise from inter-hemispheric-scale climate regimes with coherence across continents or as more local continental-scale phenomena. Similarly, extremes in individual years will be assessed for their dynamic origins and probability of occurrence.Why this research? Characterizing and understanding large-scale hydroclimate variability during the last millennium is a critical means of evaluating and improving projections of future hydroclimate change. Why this research now? Two recent developments make the time ripe for significant advances in this area of research. First, fully pan-Pacific reconstructions of last-millennium hydroclimate variability are now within reach. Second, the large and growing ensemble of last-millennium simulations with fully-coupled climate models make dynamic investigations of past hydroclimate change possible thereby providing potentially improved assessments of projected future risks and impacts.The project will help improve the understanding of extreme climatic events climate and includes a substantive leveraging of international collaboration with South American colleagues in Argentina and Chile, creation of a user-friendly drought atlas, and public outreach on science and education.