Observed positive feedback between the NAO and the North Atlantic SSTA tripole

NCEP‐NCAR reanalysis data from 1948 to 2001 are used to examine the relationship between the North Atlantic Oscillation (NAO) and the North Atlantic sea surface temperature anomaly (SSTA) tripole. It is demonstrated that the atmospheric anomalies associated with NAO produce tripole‐like sea surface temperature (SST) anomalies; in turn, the SSTA tripole produces NAO‐like atmospheric anomalies. Therefore, a positive feedback between the NAO and the SSTA tripole is suggested. The results are statistically significant; they clarify prior uncertainties associated with the relationship between the NAO and the North Atlantic SSTA tripole.