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Abstract Sea surface temperature anomaly (SSTA) modes are considered as primary sources of climate variabilities on various timescales. The North Pacific Mode (NPM), an El Niño‐Southern Oscillation‐independent, principal interannual SSTA mode in the midlatitude North Pacific during wintertime, can have a significant climate impact over the adjacent areas. However, the air‐sea coupling processes associated with NPM remain unclear, which are identified in this study. The NPM‐related SSTA develops in early winter, matures in midwinter, but decays in late winter, while the associated atmospheric anomalies exhibit a dramatic midwinter reversal. The SSTA development is forced by the atmosphere in early winter and then feedbacks upon the atmosphere through diabatic heating and transient eddy forcing, inducing a midwinter reversal of whole‐layer atmospheric anomalies. Therefore, the NPM is an atmosphere‐forced, air‐sea coupled damping mode through which, however, the ocean provides a memory mechanism responsible for how the preceding atmospheric anomaly can have a cross‐season, subsequent impact.
Tao et al. (Sat,) studied this question.