Open AccessThe North Atlantic Oscillation—what role for the Ocean?
Author(s) -
Sutton Rowan T.,
Norton Warwick A.,
Jewson Stephen P.
Publication year - 2000
Publication title -
atmospheric science letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.951
H-Index - 45
ISSN - 1530-261X
DOI - 10.1006/asle.2000.0021
Subject(s) - extratropical cyclone , climatology , north atlantic oscillation , predictability , latitude , environmental science , forcing (mathematics) , middle latitudes , tropical atlantic , atlantic multidecadal oscillation , sea surface temperature , troposphere , teleconnection , atmosphere (unit) , atmospheric sciences , geology , el niño southern oscillation , meteorology , geography , physics , geodesy , quantum mechanics
The extent to which the North Atlantic Oscillation (NAO) is influenced by changes in the ocean state is an issue that has attracted much recent attention. Although there have been counter claims, the weight of evidence clearly suggests that forcing by the ocean of year‐to‐year changes in the NAO is a weak influence by comparison with atmospheric internal variability. The NAO is thus very different in character to the Southern Oscillation (SO), and its predictability—at least on seasonal‐to‐interannual timescales—is almost certainly much lower. Although weak, the influence of the ocean on the NAO is not negligible. In a previous study we found that wintertime North Atlantic climate, including the NAO, was significantly influenced by a tripole pattern of North Atlantic SST anomalies. Here we report the results of experiments to further elucidate the nature of this influence. We show that the tripole pattern induces a significant response both in the tropical Atlantic and at mid‐to‐high latitudes. The low latitude response is forced by the low latitude SST anomalies, but the high latitude response is influenced by the extratropical SST anomalies as well as those in the tropics. Furthermore, we find evidence of nonlinear interaction between the influence of the tropical and extratropical SST anomalies. Lastly, we investigate the feedback from the atmosphere onto the SST tripole. We find that the expected negative feedback is significantly modified at low latitudes by the dynamical response of the atmosphere. Copyright © 2000 Royal Meteorological Society.