CAREER: Tree-Ring Based Reconstruction of Northern Hemisphere Jetstream Variability

北方急流是绕地球仪盘旋的高空狭窄强风路径，是中纬度极端天气事件强度和持久性的关键因素。一些研究表明，喷流可能会随着持续和未来的气候变化而减缓和改变轨迹。加州干旱、美国东部极地涡旋和2013-2014年冬季英格兰的冬季风暴就是这种行为的例证。北极放大（与低纬度地区相比，北方高纬度地区的变暖更强）可能会在近几十年内驱动急流的变化，但是，人为气候变化在急流变化中的作用是有争议的，而且仪器测量的时间太短，无法对当前和未来的急流趋势得出确切的结论。这项研究将重建过去500多年来急流的纬度位置。多年来使用树木年轮记录。该项目将产生一个新的基于树木年轮的巴尔干半岛夏季温度重建和联合收割机，它与来自西北欧的代理数据重建夏季北大西洋急流。对于冬季北太平洋喷气机，这项工作将结合联合收割机新的冬季气候敏感系列从北方落基山脉与年表从中部加州。这两个500多年的区域急流重建将用于把当前的急流趋势在历史的角度来看。这个职业生涯奖的教育部分的核心是一个新的全球变化分析课程的发展，将提供定量方法的培训，学生在广泛的，跨学科的全球变化研究社区在亚利桑那大学。该项目还包括一个多方面的外联方法，利用亚利桑那大学气候变化科学中妇女的偶然性，旨在激发后代对科学事业的兴趣。最后，该项目包括与来自保加利亚、斯洛文尼亚和瑞士的研究人员的国际合作和实地考察，包括技术知识转让（X射线密度测定），这将使美国的新能力成为可能。该项目由古气候计划和NSF国际科学与工程办公室共同支持。

The Northern Hemisphere Jet, a high altitude narrow path of strong winds that meanders around the globe, is a key factor in the strength and perseverance of mid-latitude extreme weather events. Some studies have suggested that the jet may slow and change trajectory with ongoing and future climate change. Such behavior has been exemplified by the California drought, the eastern US polar vortex, and the winter storms in England in the winter of 2013-2014. Arctic amplification (the stronger warming of high Northern Hemisphere latitudes compared to lower latitudes) may drive jet stream variability in recent decades, but the role of man-made climate change in jet stream variability is contested and the instrumental period of measurement is too short to draw firm conclusions about current and future jet stream trends.This research will reconstruct the latitudinal position of the jet over the last 500+ years using tree-ring records. The project will generate a new tree-ring based summer temperature reconstruction for the Balkans and combine it with proxy data from northwestern Europe to reconstruct the summer North Atlantic Jet. For the winter North Pacific Jet, the work will combine new winter climate-sensitive series from the northern Rockies with chronologies from central California. These two 500+ year-long regional jet stream reconstructions will be used to put current jet stream trends in a historical perspective.The centerpiece of the education component of this CAREER award is the development of a new Global Change Analysis course that would offer training in quantitative methods to students across the broad, interdisciplinary global change research community at the University of Arizona. The project also includes a multi-faceted outreach approach that capitalizes on the contingency of women in climate change science at the University of Arizona and is designed to excite future generations about science careers. Finally, the project includes international partnerships and field expeditions with researchers from Bulgaria, Slovenia, and Switzerland, including technology knowledge transfer (in x-ray densitometry) that will enable new capabilities in the US.This project is jointly supported by the Paleoclimate Program and NSF's office of International Science and Engineering.