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On the influence of stratospheric water vapor changes on the tropospheric circulation
Author(s) -
Joshi Manoj M.,
Charlton Andrew J.,
Scaife Adam A.
Publication year - 2006
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 - 10.1029/2006gl025983
Subject(s) - extratropical cyclone , troposphere , stratosphere , climatology , environmental science , context (archaeology) , predictability , atmospheric sciences , water vapor , atmospheric circulation , north atlantic oscillation , climate model , climate change , meteorology , geology , geography , oceanography , physics , paleontology , quantum mechanics
Observations suggest that the mixing ratio of water vapour in the stratosphere has increased by 20–50% between the 1960s and mid‐1990s. Here we show that inclusion of such a stratospheric water vapour (SWV) increase in a state‐of‐the‐art climate model modifies the circulation of the extratropical troposphere: the modeled increase in the North Atlantic Oscillation (NAO) index is 40% of the observed increase in NAO index between 1965 and 1995, suggesting that if the SWV trend is real, it explains a significant fraction of the observed NAO trend. Our results imply that SWV changes provide a novel mechanism for communicating the effects of large tropical volcanic eruptions and ENSO events to the extratropical troposphere over timescales of a few years, which provides a mechanism for interannual climate predictability. Finally, we discuss our results in the context of regional climate change associated with changes in methane emissions.