Stratiform cloud over the ocean with a cloud resolving model in coupled/non-coupled ocean experiments

Stratiform cloud over the ocean was investigated in numerical experiments with regional cloud resolving models (CSMs) in the non-hydrostatic system, which had been developed in mainly targeting for cumulus of high structure with deep convections. Low level cloud represented in a simulation for the case study in July 2012 showed the sensitivity to the distribution of the sea surface temperature (SST) among the coupled/non-coupled experiments with the ocean models, which were observed in the oceanic frontal zone around the Kuroshio extension off Japan Honshu Island in the western North Pacific. Liquid-water cloud patterns in the low level differed clearly among the experiments in the higher latitudinal region of the sharp SST gradient in the oceanic frontal zone, which was produced by the variation of the vertical pattern of the meridional wind. A CSM at a high resolution of 2 km or less enabled to resolve cloud vertical overlap structures directly between low and upper levels, or between solid- and liquid-water clouds. In the case study, cloud overlap was successfully represented in the experiments. It was clarified that the overlap structures varied with the distributions of the low level cloud, resulting in the apparent difference among the experiments.