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Atmospheric torques during the winter of 1989: Impact of ENSO and NAO positive phases
Author(s) -
de Viron O.,
Marcus S. L.,
Dickey J. O.
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 - 10.1029/2000gl012675
Subject(s) - arctic oscillation , forcing (mathematics) , climatology , anomaly (physics) , torque , oscillation (cell signaling) , el niño southern oscillation , angular momentum , southern oscillation , north atlantic oscillation , environmental science , atmospheric sciences , geology , physics , northern hemisphere , chemistry , biochemistry , quantum mechanics , thermodynamics , condensed matter physics
The axial component of atmospheric angular momentum (AAM) reached a decadal minimum during the winter of 1989, when the cool (La Niña) phase of the ENSO cycle and the positive phases of the North Atlantic Oscillation (NAO) and the related Arctic Oscillation (AO) were active. Here, we examine the global atmospheric dynamics associated with this event from the torque point of view. It will be shown how mountain torques on North America, South America and Europe related to these oscillations led to the AAM minimum, partly compensated by a positive ENSO‐related mountain torque over Asia. The friction torque had more nearly equal positive and negative anomalies associated with ENSO and NAO forcing, respectively, and made a smaller, offsetting contribution to the global AAM anomaly during this episode.