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The summer northern annular mode and abnormal summer weather in 2003
Author(s) -
Ogi Masayo,
Yamazaki Koji,
Tachibana Yoshihiro
Publication year - 2005
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2004gl021528
Subject(s) - climatology , empirical orthogonal functions , jet stream , northern hemisphere , arctic oscillation , forcing (mathematics) , period (music) , atmospheric circulation , environmental science , polar vortex , mode (computer interface) , north atlantic oscillation , anomaly (physics) , geography , jet (fluid) , geology , stratosphere , physics , condensed matter physics , computer science , acoustics , thermodynamics , operating system
The summer Northern Hemisphere annular mode (summer NAM), a new mode determined through empirical orthogonal function (EOF) analysis for each individual calendar month, can describe aspects of anomalous summers such as the summer of 2003, which featured warm temperatures in Europe, Canada and Russia and cold temperature in Japan. Atmospheric circulation anomalies of the summer NAM closely resemble the anomalies in the summer of 2003 and the summer NAM index was quite large during the period from mid‐July to early August when abnormal weather took place in Europe, Canada and Russia. The index includes representations of hemispheric double‐jet streams and blockings that support extended periods of abnormal weather. The double‐jet is formed and maintained by wave forcing during the period. In contrast to the Arctic and North Atlantic oscillations, the summer NAM pattern accounts for many of the anomalous weather features observed during summer of 2003.