Trouet V, Babst F, Meko M
Laboratory of Tree-Ring Research, University of Arizona, 1215 East Lowell Street, Tucson, AZ, 85721, USA.
Landscape Dynamics Unit, Swiss Federal Research Institute WSL, Zürcherstrasse 111, Birmensdorf, CH-8903, Switzerland.
Nat Commun. 2018 Jan 12;9(1):180. doi: 10.1038/s41467-017-02699-3.
A recent increase in mid-latitude extreme weather events has been linked to Northern Hemisphere polar jet stream anomalies. To put recent trends in a historical perspective, long-term records of jet stream variability are needed. Here we combine two tree-ring records from the British Isles and the northeastern Mediterranean to reconstruct variability in the latitudinal position of the high-summer North Atlantic Jet (NAJ) back to 1725 CE. We find that northward NAJ anomalies have resulted in heatwaves and droughts in northwestern Europe and southward anomalies have promoted wildfires in southeastern Europe. We further find an unprecedented increase in NAJ variance since the 1960s, which co-occurs with enhanced late twentieth century variance in the Central and North Pacific Basin. Our results suggest increased late twentieth century interannual meridional jet stream variability and support more sinuous jet stream patterns and quasi-resonant amplification as potential dynamic pathways for Arctic warming to influence mid-latitude weather.
近期中纬度极端天气事件的增加与北半球极地急流异常有关。为了从历史角度看待近期趋势，需要长期的急流变化记录。在这里，我们结合了来自不列颠群岛和地中海东北部的两个树木年轮记录，以重建公元1725年以来盛夏北大西洋急流（NAJ）纬度位置的变化。我们发现，NAJ向北异常导致了欧洲西北部的热浪和干旱，向南异常则促进了欧洲东南部的野火。我们还发现，自20世纪60年代以来，NAJ的变化出现了前所未有的增加，这与20世纪后期中太平洋和北太平洋盆地变化的增强同时发生。我们的结果表明，20世纪后期年际经向急流变化增加，并支持更蜿蜒的急流模式和准共振放大，作为北极变暖影响中纬度天气的潜在动态途径。
