McGee D, Moreno-Chamarro E, Marshall J, Galbraith E D
Department of Earth, Atmospheric and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.
Institut de Ciència i Tecnologia Ambientals (ICTA) and Department of Mathematics, Universitat Autonoma de Barcelona, 08193 Barcelona, Spain.
Sci Adv. 2018 Nov 28;4(11):eaav0118. doi: 10.1126/sciadv.aav0118. eCollection 2018 Nov.
Lake and cave records show that winter precipitation in the southwestern United States increased substantially during millennial-scale periods of Northern Hemisphere winter cooling known as Heinrich stadials. However, previous work has not produced a clear picture of the atmospheric circulation changes driving these precipitation increases. Here, we combine data with model simulations to show that maximum winter precipitation anomalies were related to an intensified subtropical jet and a deepened, southeastward-shifted Aleutian Low, which together increased atmospheric river-like transport of subtropical moisture into the western United States. The jet and Aleutian Low changes are tied to the southward displacement of the intertropical convergence zone and the accompanying intensification of the Hadley circulation in the central Pacific. These results refine our understanding of atmospheric changes accompanying Heinrich stadials and highlight the need for accurate representations of tropical-extratropical teleconnections in simulations of past and future precipitation changes in the region.
湖泊和洞穴记录显示，在美国西南部，冬季降水在被称为海因里希冰期的北半球冬季千年尺度降温期间大幅增加。然而，此前的研究尚未清晰描绘出导致这些降水增加的大气环流变化情况。在此，我们将数据与模型模拟相结合，以表明冬季最大降水异常与增强的副热带急流以及加深且向东南移动的阿留申低压有关，这两者共同增加了类似大气河流的副热带水汽向美国西部的输送。急流和阿留申低压的变化与热带辐合带的南移以及中太平洋伴随出现的哈德利环流增强有关。这些结果完善了我们对伴随海因里希冰期的大气变化的理解，并突出了在该地区过去和未来降水变化模拟中准确呈现热带 - 温带遥相关的必要性。
