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mountain torques and atmospheric oscillations
Author(s) -
Lott François,
Robertson Andrew W.,
Ghil Michael
Publication year - 2001
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 - 10.1029/2000gl011829
Subject(s) - atmospheric circulation , climatology , middle latitudes , northern hemisphere , jet stream , arctic oscillation , oscillation (cell signaling) , atmospheric sciences , pacific decadal oscillation , jet (fluid) , gcm transcription factors , southern hemisphere , westerlies , geology , arctic , circulation (fluid dynamics) , environmental science , general circulation model , climate change , oceanography , physics , el niño southern oscillation , thermodynamics , genetics , biology
Theoretical work and general circulation model (GCM) experiments suggest that the midlatitude jet stream's interaction with large‐scale topography can drive intraseasonal oscillations in large‐scale atmospheric circulation patterns. In support of this theory, we present new observational evidence that mountain‐induced torques play a key role in 15–30‐day oscillations of the Northern Hemisphere circulation's dominant patterns. The affected patterns include the Arctic Oscillation (AO) and the Pacific‐North‐American (PNA) pattern. Positive torques both accelerate and anticipate the midlatitude westerly winds at these periodicities. Moreover, torque anomalies anticipate the onsets of weather regimes over the Pacific, as well as the break‐ups of hemispheric‐scale regimes.