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Article
Characteristics of Observed Atmospheric Circulation Patterns Associated with Temperature Extremes over North America
Journal of Climate (2012)
  • Paul C. Loikith, Portland State University
  • Anthony J. Broccoli, Rutgers University - New Brunswick/Piscataway
Abstract
Motivated by a desire to understand the physical mechanisms involved in future anthropogenic changes in
extreme temperature events, the key atmospheric circulation patterns associated with extreme daily temperatures
over North America in the current climate are identified. The findings show that warm extremes at
most locations are associated with positive 500-hPa geopotential height and sea level pressure anomalies just
downstream with negative anomalies farther upstream. The orientation, physical characteristics, and spatial
scale of these circulation patterns vary based on latitude, season, and proximity to important geographic
features (i.e., mountains, coastlines). The anomaly patterns associated with extreme cold events tend to be
similar to, but opposite in sign of, those associated with extreme warm events, especially within the westerlies,
and tend to scale with temperature in the same locations. Circulation patterns aloft are more coherent across
the continent than those at the surface where local surface features influence the occurrence of and patterns
associated with extreme temperature days. Temperature extremes may be more sensitive to small shifts in
circulation at locations where temperature is strongly influenced by mountains or large water bodies, or at the
margins of important large-scale circulation patterns making such locations more susceptible to nonlinear
responses to future climate change. The identification of these patterns and processes will allow for a thorough
evaluation of the ability of climate models to realistically simulate extreme temperatures and their future
trends.
Publication Date
April 18, 2012
DOI
10.1175/JCLI-D-11-00709.1
Publisher Statement
*At the time of publication Paul C. Loikith was affiliated with Rutgers University.
Citation Information
Loikith, P. C., & Broccoli, A. J. (2012). Characteristics of observed atmospheric circulation patterns associated with temperature extremes over North America. Journal of Climate, 25(20), 7266-7281.