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AO/NAO Response to Climate ChangeUsing a variety of GCM experiments with various versions of the GISS model, we investigate how different aspects of tropospheric climate changes affect the extratropical Arctic Oscillation (AO)/North Atlantic Oscillation (NAO) circulation indices. The results show that low altitude changes in the extratropical latitudinal temperature gradient can have a strong impact on eddy forcing of the extratropical zonal wind, in the sense that when this latitudinal temperature gradient increases, it helps force a more negative AO/NAO phase. In addition, local conditions at high latitudes can stabilize/destabilize the atmosphere, inducing negative/positive phase changes. To the extent that there is not a large temperature change in the tropical upper troposphere (either through reduced tropical sensitivity at the surface, or limited transport of this change to high levels), the changes in the low level temperature gradient can provide the dominate influence on the extratropical circulation, so that planetary wave meridional refraction and eddy angular momentum transport changes become uncorrelated with potential vorticity transports. In particular, the climate change that produces the most positive NAO phase change would have substantial warming in the tropical upper troposphere over the Pacific Ocean, with high latitude warming in the North Atlantic. An increase in positive phase of these circulation indices is still more likely than not, but it will depend on the degree of tropical and high latitude temperature response and the transport of low level warming into the upper troposphere. These are aspects that currently differ among the models used for predicting the effects of global warning, contributing to the lack of consensus of future changes in the AO/NAO.
Document ID
20070034993
Acquisition Source
Goddard Space Flight Center
Document Type
Reprint (Version printed in journal)
External Source(s)
Authors
Rind, D.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Perlwitz, J.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Lonergan, P.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Lerner, J.
(NASA Goddard Inst. for Space Studies New York, NY, United States)
Date Acquired
August 24, 2013
Publication Date
June 21, 2005
Publication Information
Publication: Journal of Geophysical Research
Publisher: American Geophysical Union
Volume: 110
Subject Category
Meteorology And Climatology
Funding Number(s)
CONTRACT_GRANT: NNX06AC95G
Distribution Limits
Public
Copyright
Other

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