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

该项目的总目标是利用树木年轮记录编制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)十年至百年水文气候变率的半球间机制；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响应）；4)过去的水文气候干旱事件，参考其潜在的动力学，从而提供了对上个千年中一些最具破坏性的气候事件的见解。将分析水文气候模式的相关动力学，并诊断其与大尺度变率模式和/或强迫变化模式的联系。将对多年代际水文气候异常（例如特大干旱或雨淋）进行评估，以确定它们是来自具有跨大陆一致性的半球尺度气候制度，还是作为更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。为什么要做这项研究？表征和了解过去一千年的大尺度水文气候变率是评价和改进未来水文气候变化预估的关键手段。为什么现在进行这项研究？最近的两项发展使这一研究领域取得重大进展的时机成熟。首先，全面重建上一千年的泛太平洋水文气候变化现在已经触手可及。其次，使用完全耦合的气候模式的上一千年模拟的庞大和不断增长的集合使得对过去水文气候变化的动态调查成为可能，从而为预估的未来风险和影响提供潜在改进的评估。该项目将有助于提高对极端气候事件的认识，包括实质性地利用与阿根廷和智利的南美同行的国际合作，创建一个用户友好的干旱地图集，以及在科学和教育方面进行公众宣传。

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.