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North-south dipole in winter hydroclimate in the western United States during the last deglaciation

March 22, 2019

During the termination of the last glacial period the western U.S. experienced exceptionally wet conditions, driven by changes in location and strength of the mid-latitude winter storm track. The distribution of modern winter precipitation is frequently characterized by a north-south wet/dry dipole pattern, controlled by interaction of the storm track with ocean-atmosphere conditions over the Pacific and Atlantic Oceans. Here we show that a dipole pattern of similar geographic extent persisted and switched sign during millennial-scale abrupt climate changes of the last deglaciation, based on a new lake level reconstruction for pluvial Lake Chewaucan (northwestern U.S.), and a compilation of regional paleoclimate records. This suggests the dipole pattern is robust, and one mode may be favored for centuries, thereby creating persistent contrasting wet/dry conditions across the western U.S. The TraCE-21k climate model simulation shows an equatorward enhancement of winter storm track activity in the northeastern Pacific, favoring wet conditions in southwestern U.S. during the second half of Heinrich Stadial 1 (16.1–14.6 ka) and consistent with paleoclimate evidence. During the Bølling/Allerød (14.6–12.8 ka), the northeastern Pacific storm track contracted poleward, consistent with wetter conditions concentrated poleward toward the northwest U.S.

Citation Information

Publication Year 2019
Title North-south dipole in winter hydroclimate in the western United States during the last deglaciation
DOI 10.1038/s41598-019-41197-y
Authors Adam M. Hudson, Benjamin J. Hatchett, Jay Quade, Douglas P. Boyle, Scott D. Bassett, Guleed Ali, Marie G. De los Santos
Publication Type Article
Publication Subtype Journal Article
Series Title Scientific Reports
Series Number
Index ID 70202751
Record Source USGS Publications Warehouse
USGS Organization Geosciences and Environmental Change Science Center