Suppression of Cold Weather Events over High-Latitude Continents in Warm Climates
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jcli-d-18-0129.1.pdf
Description
Published version
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12.81 MB
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Checksum (MD5)
91a992278559ce244b1ab8afe1bed053
Author(s)
Hu, Zeyuan
Cronin, Timothy Wallace
Tziperman, Eli
Date Issued
November 2018
Journal
Journal of Climate
Publisher
American Meteorological Society
Citation
Hu, Zeyuan et al., "Suppression of Cold Weather Events over High-Latitude Continents in Warm Climates." Journal of Climate 31, 23 (December 2018): 9625-40 doi. 10.1175/JCLI-D-18-0129.1 ©2018 Authors
Version
Final published version
Abstract
Recent studies, using Lagrangian single-column atmospheric models, have proposed that in warmer climates more low clouds would form asmaritime airmasses advect intoNorthernHemisphere high-latitude continental interiors during winter (DJF). This increase in low cloud amount and optical thickness could reduce surface radiative cooling and suppressArctic air formation events, partly explaining both the warmwinter high-latitude continental interior climate and frost-intolerant species found there during the Eocene and the positive lapserate feedback in future Arctic climate change scenarios. Here the authors examine the robustness of this lowcloud mechanism in a three-dimensional atmospheric model that includes large-scale dynamics. Different warming scenarios are simulated under prescribed CO2 and sea surface temperature, and the sensitivity of winter temperatures and clouds over high-latitude continental interior to mid- and high-latitude sea surface temperatures is examined. Model results show that winter 2-m temperatures on extreme cold days increase about 50% faster than the winter mean temperatures and the prescribed SST. Low cloud fraction and surface longwave cloud radiative forcing also increase in both the winter mean state and on extreme cold days, consistent with previous Lagrangian air-mass studies, but with cloud fraction increasing for different reasons than proposed by previous work. At high latitudes, the cloud longwave warming effect dominates the shortwave cooling effect, and the net cloud radiative forcing at the surface tends to warm high-latitude land but cool midlatitude land. This could contribute to the reducedmeridional temperature gradient in warmer climates and help explain the greater warming of winter cold extremes relative to winter mean temperatures. ©2018 American Meteorological Society.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
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DOI of Published Version
https://doi.org/10.1175/JCLI-D-18-0129.1
