Propagation characteristic of atmospheric responses to abnormal warm SST in the Kuroshio Extension in winter

The propagation characteristic of atmospheric responses to the abnormal warm sea-surface temperature (SST) in the Kuroshio Extension in winter was investigated using National Centre for Atmospheric Research CAM3.0. The results show that geopotential height perturbations at 500 hPa occupy much of the mid- and high-latitude areas north of 20°N and are stronger in winter and spring than in summer. Power spectrum analysis reveals that the perturbations contain both quasi-biweekly and intraseasonal oscillations. In the latitude band with maximum perturbation amplitude, the oscillations propagate mainly eastward. The centers of dominant oscillations are situated in the mid- and higher-latitude areas north to 40°N. The perturbations in the Arctic mainly propagate meridionally, whereas those south of the Arctic propagate zonally, at a steady-phase velocity basically. The propagation characteristics of wind perturbations and temperature perturbations are similar to those of geopotential height perturbations.