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

University Of Arizona, Tucson AZ

Investigators

Abstract

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.