TY - JOUR
T1 - Recent amplification of the North American winter temperature dipole
AU - Singh, Deepti
AU - Swain, Daniel L.
AU - Mankin, Justin S.
AU - Horton, Daniel E.
AU - Thomas, Leif N.
AU - Rajaratnam, Bala
AU - Diffenbaugh, Noah S.
N1 - Funding Information:
We thank the National Oceanic and Atmospheric Administration’s NCDC for access to historical temperature and geopotential height data sets, PRISM Climate Group and University of Idaho for access to historical temperature data sets, and NCAR for access to the CESM LENS simulations. We also thank Nathaniel Johnson for providing us the Self-Organizing Maps algorithm. Our work is supported by the Lamont Doherty Postdoctoral Fellowship to D.S.; graduate fellowships from the Switzer Foundation and the ARCS Foundation to D.L.S.; Earth Institute Postdoctoral Fellowship to J.S.M.; US National Science Foundation grants DMS-CMG 1025465, AGS-1003823, DMS-1106642, and DMS-CAREER-1352656; and U.S. Air Force Office of Scientific Research grant award FA9550-13-1-0043 to B.R.; and NSF AGS CAREER grant 0955283 and DOE Integrated Assessment Research Program grant DE-SC005171 to N.S.D. Gridded 2 m temperatures, geopotential heights, meridional winds, and omega from the NCEP R1 and 2 m temperatures from the NCEP North American Regional Reanalysis (NARR) are available at the NOAA ESRL website (http://www.esrl.noaa.gov/psd/data/ gridded/). Gridded temperatures from PRISM Climate Group and University of Idaho Metdata data sets are available at their respective websites (http://www. prism.oregonstate.edu/ and http://met-data.northwestknowledge.net/). All analysis scripts used in this study can be obtained by contacting Deepti Singh (dsingh@ldeo.columbia.edu).
Publisher Copyright:
© 2016. The Authors.
PY - 2016
Y1 - 2016
N2 - During the winters of 2013-2014 and 2014-2015, anomalously warm temperatures in western North America and anomalously cool temperatures in eastern North America resulted in substantial human and environmental impacts. Motivated by the impacts of these concurrent temperature extremes and the intrinsic atmospheric linkage between weather conditions in the western and eastern United States, we investigate the occurrence of concurrent “warm-West/cool-East” surface temperature anomalies, which we call the “North American winter temperature dipole.” We find that, historically, warm-West/cool-East dipole conditions have been associated with anomalous mid-tropospheric ridging over western North America and downstream troughing over eastern North America. We also find that the occurrence and severity of warm-West/cool-East events have increased significantly between 1980 and 2015, driven largely by an increase in the frequency with which high-amplitude “ridge-trough” wave patterns result in simultaneous severe temperature conditions in both the West and East. Using a large single-model ensemble of climate simulations, we show that the observed positive trend in the warm-West/cool-East events is attributable to historical anthropogenic emissions including greenhouse gases, but that the co-occurrence of extreme western warmth and eastern cold will likely decrease in the future as winter temperatures warm dramatically across the continent, thereby reducing the occurrence of severely cold conditions in the East. Although our analysis is focused on one particular region, our analysis framework is generally transferable to the physical conditions shaping different types of extreme events around the globe.
AB - During the winters of 2013-2014 and 2014-2015, anomalously warm temperatures in western North America and anomalously cool temperatures in eastern North America resulted in substantial human and environmental impacts. Motivated by the impacts of these concurrent temperature extremes and the intrinsic atmospheric linkage between weather conditions in the western and eastern United States, we investigate the occurrence of concurrent “warm-West/cool-East” surface temperature anomalies, which we call the “North American winter temperature dipole.” We find that, historically, warm-West/cool-East dipole conditions have been associated with anomalous mid-tropospheric ridging over western North America and downstream troughing over eastern North America. We also find that the occurrence and severity of warm-West/cool-East events have increased significantly between 1980 and 2015, driven largely by an increase in the frequency with which high-amplitude “ridge-trough” wave patterns result in simultaneous severe temperature conditions in both the West and East. Using a large single-model ensemble of climate simulations, we show that the observed positive trend in the warm-West/cool-East events is attributable to historical anthropogenic emissions including greenhouse gases, but that the co-occurrence of extreme western warmth and eastern cold will likely decrease in the future as winter temperatures warm dramatically across the continent, thereby reducing the occurrence of severely cold conditions in the East. Although our analysis is focused on one particular region, our analysis framework is generally transferable to the physical conditions shaping different types of extreme events around the globe.
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U2 - 10.1002/2016JD025116
DO - 10.1002/2016JD025116
M3 - Article
C2 - 27840780
AN - SCOPUS:84984679665
VL - 121
SP - 9911
EP - 9928
JO - Journal of Geophysical Research: Biogeosciences
JF - Journal of Geophysical Research: Biogeosciences
SN - 0148-0227
IS - 17
ER -