Observed Linkages Between the Atmospheric Circulation and Oceanic-Forced Sea-Surface Temperature Variability in the Western North Pacific

Previous research suggests the extratropical atmospheric circulation responds to that sea-surface temperature (SST) variability in the western North Pacific. However, the relative roles of oceanic and atmospheric processes in driving the SST anomalies that, in turn, seemingly influence the atmospheric circulation are unclear. Here, we exploit a simple stochastic climate model to subdivide the SST variability in the Kuroshio-Oyashio Extension region into components forced by oceanic and atmospheric processes. We then probe the lead/lag relationships between the atmospheric circulation and both components of the SST variability. Importantly, only the oceanic-forced SST variability is associated with robust atmospheric anomalies that lag the SSTs by 1 month. The results are consistent with the surface heat fluxes associated with atmospheric and oceanic-forced components of the SST variability. Overall, the findings suggest that ocean dynamical processes in the western North Pacific play an important role in influencing the variability of the extratropical circulation.

Automated summary

Previous research has shown that the extratropical atmospheric circulation is influenced by sea-surface temperature (SST) variability in the western North Pacific. However, the relative contributions of oceanic and atmospheric processes to the SST anomalies and their impact on the atmospheric circulation are not well understood. In this study, a simple stochastic climate model was used to separate SST variability in the Kuroshio-Oyashio Extension region into components forced by oceanic and atmospheric processes. The results indicate that only the ocean-forced SST variability is associated with significant atmospheric anomalies that occur one month later. These findings suggest that ocean dynamical processes in the western North Pacific play an important role in influencing the variability of the extratropical circulation.