资源环境科技发展态势分析平台

Supercooled liquid clouds are an important component of the albedo of the Southern Ocean (

SO). While ice phase occurrence in liquid‐dominant clouds (hereafter mixed‐phase) at temperatures warmer than the homogeneous freezing point is rare in the SO, the processes that create mixed‐phase clouds are not understood. Using data from the CALIPSO lidar, we reconsider the thresholds of layer‐integrated depolarization ratio and layer‐integrated attenuated backscatter that are used to diagnose the phases of fully attenuating cloud layers. We argue that liquid‐only clouds have understood physical bounds to these thresholds allowing for unique identification of layers that are not consistent with the presence of single‐phase liquid tops. Compared to the original phase algorithm the application of these physically constrained thresholds results in a ~70% increase in mixed‐phase during the annual cycle considered. Combining the CALIPSO data with CloudSat data, mixed‐phase clouds seem to typically co‐occur with precipitation implying secondary ice forming processes.