Stratocumulus in the Cold and Warm Sides of the Spring Kuroshio Sea Surface Temperature Front in the East China Sea

The characteristics and formation mechanisms of stratocumulus (Sc) clouds were investigated in this study based on satellite and sounding data from March and April 2007-2010. The effects of the intensity of the Kuroshio sea surface temperature (SST) front on the amount and height of Sc clouds were also assessed by composite analysis. Sc clouds mainly occurred lower than 3 km as single-layer clouds, and there was a larger amount of clouds in the warm side than in the cold side of the Kuroshio area. This difference occurred because the Kuroshio SST front produced different dynamics and thermal structures in the planetary boundary layer (PBL) of the warm and cold sides. Both the strong local sensible heat flux forced by strong northwesterly winds and the large relative humidity in the PBL favored the formation of Sc clouds in the warm side. In the cold side, both the strong temperature inversion caused by downdrafts and the PBL top height hindered cloud development, similar to the cloud formation conditions in the subtropical oceans near California. Furthermore, the amount and height of clouds were influenced by the Kuroshio SST front intensity. In the warm side, more abundant clouds and a higher cloud height were associated with a strong SST front background than with a weak SST front background.