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Evolving Impacts of Multiyear La Niña Events on Atmospheric Circulation and U.S. Drought
Author(s) -
Okumura Yuko M.,
DiNezio Pedro,
Deser Clara
Publication year - 2017
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 - 10.1002/2017gl075034
Subject(s) - teleconnection , climatology , precipitation , atmospheric circulation , environmental science , walker circulation , sea surface temperature , general circulation model , zonal and meridional , atmospheric sciences , la niña , climate change , oceanography , geology , el niño southern oscillation , geography , meteorology
Wintertime precipitation over the southern U.S. is known to decrease with interannual cooling of the equatorial Pacific associated with La Niña, which often persists 2 years or longer. Composite analysis based on a suite of observational and reanalysis data sets covering the period 1901–2012 reveals distinct evolution of atmospheric teleconnections and U.S. precipitation anomalies during multiyear La Niña events. In particular, atmospheric circulation anomalies strengthen and become more zonally elongated over the North Pacific in the second winter compared to the first winter. U.S. precipitation deficits also remain large, while the region of reduced precipitation shifts northeastward in the second winter. This occurs despite a significant weakening of the equatorial Pacific cooling in the second winter and suggests that the large‐scale atmospheric circulation is more sensitive to tropical sea surface temperature anomalies of broader meridional extent. Given the extended climatic impacts, accurate prediction of La Niña duration is crucial.