The atmospheric response to Oyashio front shifts in atmospheric GCMs

We investigate the atmospheric response to Oyashio SST front variability by forcing a high-resolution (0.25°) GCM with SST anomalies seen during typical north/south shifts of the Oyashio front during the boreal winter. The local response is an anomalous, thermally direct vertical circulation extending through most of the troposphere, accompanied by a weak negative sea-level pressure (SLP) anomaly. Meanwhile, the downstream response is a significant weakening of the Aleutian Low associated with a northward shifted Oyashio front, which is remarkably persistent across individual months. An analogous simulation using the 1° version of the same GCM reveals no downstream response. The 0.25° GCM appears more consistent with observations in two regards: the relatively weak local SLP response, and the deeper extent of the anomalous vertical circulation. Consequently, the larger emphasis on anomalous vertical heat transport in the 0.25° GCM, as opposed to horizontal heat transport in the 1° GCM, may be more efficient in forcing changes in the storm track.