Abstract. Marine atmospheric boundary layer clouds cover vast areas of the Southern Ocean (SO), where they are commonly organized into mesoscale cellular convection (MCC). Using three years of Himawari-8 geostationary satellite observations, open and closed MCC structures are identified using a hybrid convolutional neural network. The results of the climatology show that open MCC clouds are roughly uniformly distributed over the SO storm track across mid-latitudes, while closed MCC clouds are most predominant in the southeast Indian Ocean with a second maximum along the storm track. The ocean polar front, derived from ECMWF-ERA5 sea surface temperature gradients, is found to be aligned with the southern boundaries for both MCC types. Along the storm track, both closed and open MCCs are commonly located in post-frontal, cold air masses. The hourly classification of closed MCC reveals a pronounced daily cycle, with a peak occurring late night/early morning. Seasonally, the diurnal cycle of closed MCC is most intense during the summer months (DJF). Conversely, almost no diurnal cycle is evident for open MCC.

中文翻译：

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从 Himawari-8 观测得出的南大洋上空开放和封闭中尺度细胞对流的气候学

摘要。海洋大气边界层云覆盖了南大洋 (SO) 的广大区域，在那里它们通常被组织成中尺度蜂窝对流 (MCC)。使用三年的 Himawari-8 对地静止卫星观测，使用混合卷积神经网络识别开放和封闭的 MCC 结构。气候学结果表明，开放的 MCC 云在中纬度 SO 风暴轨迹上大致均匀分布，而闭合的 MCC 云在印度洋东南部最为占主导地位，沿风暴轨迹的第二个最大值。发现源自 ECMWF-ERA5 海面温度梯度的海洋极地锋与两种 MCC 类型的南部边界对齐。沿着风暴路径，封闭式和开放式 MCC 通常位于后锋冷气团中。封闭式 MCC 的每小时分类显示出明显的每日周期，峰值出现在深夜/清晨。季节性地，封闭式 MCC 的昼夜循环在夏季月份 (DJF) 最为强烈。相反，对于开放性 MCC，几乎没有明显的昼夜循环。