Sep 2, 2011

Recent warm and cold daily winter temperature extremes in the Northern Hemisphere

Guirguis, Kristen, Gershunov, Alexander, Schwartz, Rachel, Bennett, Stephen
Geophysical Research Letters
  • Reviews that the winters of 2009–2010 and 2010–2011 brought frigid temperatures to parts of Europe, Russia, and the U.S.
  • Analyzes regional and Northern Hemispheric (NH) daily temperature extremes for these two consecutive winters in the historical context of the past 63 years
  • Finds that while some parts clearly experienced very cold temperatures, the NH was not anomalously cold, and that extreme warm events were much more prevalent in both magnitude and spatial extent
  • Finds that the persistent negative state of the North Atlantic Oscillation (NAO) explained the bulk of the observed cold anomalies, however the warm extremes were anomalous even accounting for the NAO and also considering the states of the Pacific Decadal Oscillation (PDO) and El Niño Southern Oscillation (ENSO)
  • Results indicate the winters' widespread and intense warm extremes together with a continuing hemispheric decline in cold snap activity was a pattern fully consistent with a continuation of the warming trend observed in recent decades