Changes in North American atmospheric circulation and extreme weather: Influence of arctic amplification and northern hemisphere snow cover

Stephen J. Vavrus, Fuyao Wang, Jonathan E. Martin, Jennifer Francis, Yannick Peings, Julien Cattiaux

Research output: Contribution to journalArticle

29 Citations (Scopus)

Abstract

This study tests the hypothesis that Arctic amplification (AA) of global warming remotely affects midlatitudes by promoting a weaker, wavier atmospheric circulation conducive to extreme weather. The investigation is based on the late twenty-first century over greater North America (20°-90°N, 50°-160°W) using 40 simulations from the Community Earth System Model Large Ensemble, spanning 1920-2100. AA is found to promote regionally varying ridging aloft (500 hPa) with strong seasonal differences reflecting the location of the strongest surface thermal forcing. During winter, maximum increases in future geopotential heights are centered over the Arctic Ocean, in conjunction with sea ice loss, but minimum height increases (troughing) occur to the south, over the continental United States. During summer the location of maximum height inflation shifts equatorward, forming an annular band across mid-to-high latitudes of the entire Northern Hemisphere. This band spans the continents, whose enhanced surface heating is aided by antecedent snow-cover loss and reduced terrestrial heat capacity. Through the thermal wind relationship, midtropospheric winds weaken on the equatorward flank of both seasonal ridging anomalies-mainly over Canada during winter and even more over the continental United States during summer-but strengthen elsewhere to form a dipole anomaly pattern in each season. Changes in circulation waviness, expressed as sinuosity, are inversely correlated with changes in zonal wind speed at nearly all latitudes, both in the projections and as observed during recent decades. Over the central United States during summer, the weaker and wavier flow promotes drying and enhanced heating, thus favoring more intense summer weather.

Original languageEnglish (US)
Pages (from-to)4317-4333
Number of pages17
JournalJournal of Climate
Volume30
Issue number11
DOIs
StatePublished - Jun 1 2017

Fingerprint

snow cover
atmospheric circulation
amplification
Northern Hemisphere
weather
summer
heating
anomaly
heat capacity
winter
twenty first century
zonal wind
geopotential
inflation
sea ice
global warming
wind velocity
simulation
loss

All Science Journal Classification (ASJC) codes

  • Atmospheric Science

Keywords

  • Arctic
  • Atmosphere
  • Atmospheric circulation
  • Climate models
  • North America
  • Snow cover

Cite this

Vavrus, Stephen J. ; Wang, Fuyao ; Martin, Jonathan E. ; Francis, Jennifer ; Peings, Yannick ; Cattiaux, Julien. / Changes in North American atmospheric circulation and extreme weather : Influence of arctic amplification and northern hemisphere snow cover. In: Journal of Climate. 2017 ; Vol. 30, No. 11. pp. 4317-4333.
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Changes in North American atmospheric circulation and extreme weather : Influence of arctic amplification and northern hemisphere snow cover. / Vavrus, Stephen J.; Wang, Fuyao; Martin, Jonathan E.; Francis, Jennifer; Peings, Yannick; Cattiaux, Julien.

In: Journal of Climate, Vol. 30, No. 11, 01.06.2017, p. 4317-4333.

Research output: Contribution to journalArticle

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