Response of atmospheric circulation to multiscale SST anomaly associated with Kuroshio Extension decadal variability warming in winter

The response of atmospheric circulation to sea surface temperature anomaly (SSTA) of different scales in extratropical oceans has always been a popular issue in air-sea interactions, especially regarding the influence of widely active, small-scale ocean eddies on the atmosphere. Based on the regional climate model RegCM4.6, three sets of ensemble experiments with different initial values were designed, and the response of atmospheric circulation and possible mechanisms to Kuroshio Extension Decadal Variability SSTA with different scales (KEDV-induced SSTA) during winter were discussed. The response of atmospheric circulation to the KEDV-induced mesoscale SSTA presents a broadly tripolar pattern, while the response to the KEDV-induced large-scale SSTA presents a baroclinic structure in the central Pacific and a dipole-type response with a barotropic structure in the eastern Pacific. Further diagnostic analysis shows that under the influence of mesoscale SSTA, transient eddy activity is strengthened, and feedback of transient eddy plays a major role in the large-scale circulation anomaly in the central-eastern Pacific. The associated barotropic energy conversion also plays an important role in maintaining the large-scale circulation anomaly in the northwestern Pacific Ocean. Under the influence of large-scale SSTA, diabatic heating is stronger, and the feedback of diabatic heating plays a major role in the large-scale circulation anomaly.