The impact of cloud radiative feedback, remote ENSO forcing, and entrainment on the persistence of north Pacific sea surface temperature anomalies

Positive radiative feedback enhances SST autocorrelations (~0.1-0.3) from late spring to summer in the central and western Pacific and from late summer to fall in the subtropical eastern Pacific. The influence of the remote ENSO forcing on SST autocorrelation varies with season and location with a maximum impact on the correlation magnitude of 0.2-0.3. The winter-to-winter recurrence of higher autocorrelations is caused by entrainment, which generally suppresses SST variability but returns thermal anomalies sequestered beneath the mixed layer in summer back to the surface in the following fall/winter.

This reemergence mechanism enhances SST autocorrelation by ~0.3 at lags of 9-12 months from the previous winter in the western and central Pacific, but only slightly enhances autocorrelation (~0.1) in the subtropical eastern Pacific. The impact of clouds, ENSO, and entrainment on the autocorrelation structure of the basinwide SST anomaly pattern is similar to that in the western region. ENSO's impact on the basinwide North Pacific SST autocorrelation in an atmospheric general circulation model coupled to an ocean mixed layer model with observed SSTs specified in the tropical Pacific is very similar to the results from the stochastic model developed here.