Atmosphere‐ocean thermal coupling in the North Atlantic: A positive feedback

作者：Masahiro Watanabe, Masahide Kimoto · 发表于：Quarterly Journal of the Royal Meteorological Society · 年份：2000 · DOI：10.1002/qj.49712657017 · 被引用次数：531 · 研究领域：Climate variability and models、Oceanographic and Atmospheric Processes、Meteorological Phenomena and Simulations

Abstract In this article, it is examined whether a positive atmosphere‐ocean feedback is found over the North Atlantic through a series of general circulation model (GCM) experiments. A 60‐year integration of an atmospheric GCM (AGCM) coupled with a 50 m deep motionless ocean was conducted. The coupled run was compared with two uncoupled runs, one with prescribed mid‐latitude climato‐logical sea surface temperatures (SSTs) and the other with daily SSTs derived from the coupled experiment. The uncoupled atmosphere forces the slab ocean, to obtain SST responses in these runs. Consistent with previous studies, the coupled atmosphere‐ocean fields show interannual variances larger than those in the uncoupled runs, due to reduction in the local thermal damping. Patterns of maximum atmosphere‐ocean covariability show the North Atlantic Oscillation (NAO) and tripole SST anomalies both in the coupled and uncoupled fields, indicating a dominant role of the atmosphere in generating the SST anomalies. On the other hand, analyses of the temporal variability in the three runs suggest an active role of SST anomalies in determining the polarity of the air‐sea coupled variability longer than the interannual time‐scale. A combined analysis of forcing SST, upper‐air height, and the response SST anomalies in the uncoupled run identified that a patch of positive SST anomalies in the mid‐latitude band around 40°N effectively excite the positive phase of the NAO, which in turn reinforces the tripol...