Relationship between North Atlantic Oscillation (NAO) and North Atlantic SSTA tripole

In this study, we explored the relationship between the atmospheric internal variability and the SST anomaly pattern in the North Atlantic region. A five-layer primitive equation model with synoptic eddy and low-frequency flow (SELF) feedback was coupled with an ocean mixed layer model to study the effect of air-sea coupling on the North Atlantic Oscillation (NAO). It is shown that the NAO-like atmospheric circulation anomalies can produce tripole-like SST anomalies in the North Atlantic region and a NAO-like dipole with an equivalent barotropic structure over the Atlantic can be excited by the North Atlantic SST tripole. The NAO-like response is primarily maintained by a positive SELF feedback that results from interactions between the heating-forced anomalous flow and the Atlantic storm track. Without SELF feedback, this covarying pattern can not exist.