Pockets of open cells (POCs) have been shown to develop within closed-cell stratocumulus (StCu), and a large body of evidence suggests that the development of POCs result from changes in small-scale processes internal to the boundary layer rather than large-scale forcings. Precipitation is widely viewed as a key process important to POC development and maintenance. In this study, GOES-16 satellite observations are used in conjunction with MERRA-2 winds to track and compare the microphysical and environmental evolution of two populations of closed-cell StCu selected by visual inspection over the southeastern Pacific Ocean: one group that transitions to POCs and another comparison group (CLOSED) that does not. The high spatiotemporal resolution of the new GOES-16 data allows for a detailed examination of the temporal evolution of POCs in this region. We find that POCs tend to develop near the coast, last tens of hours, are larger than 10⁴ km², and often (88 % of cases) do not re-close before they exit the StCu deck. Most POCs are observed to form at night and tend to exit the StCu during the day when the StCu is contracting in area. Relative to the CLOSED trajectories, POCs have systematically larger effective radii, lower cloud drop number concentrations, a comparable conditional in-cloud liquid water path, and a higher frequency of more intense precipitation. Meanwhile, no systematic environmental differences other than boundary layer height are observed between POC and CLOSED trajectories. Interestingly, there are no differences in reanalysis aerosol optical depth between both sets of trajectories, which may lead one to the interpretation that differences in aerosol concentrations are not influencing POC development or resulting in a large number that re-close. However, this largely depends on the reanalysis treatment of aerosol–cloud interactions, and the product used in this study has no explicit handling of these important processes. These results support the consensus view regarding the importance of precipitation on the formation and maintenance of POCs and demonstrate the utility of modern geostationary remote sensing data in evaluating the POC life cycle.

中文翻译：

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太平洋东南部开放单元的拉格朗日分析

开孔囊袋 (POCs) 已被证明在闭孔层积云 (StCu) 中发展，大量证据表明 POCs 的发展是由于边界层内部小规模过程的变化而不是大尺度过程的变化。尺度强迫。降水被广泛视为对 POC 开发和维护很重要的关键过程。在这项研究中，GOES-16 卫星观测与 MERRA-2 风一起使用，以跟踪和比较东南太平洋上通过目测选择的两个闭孔 StCu 种群的微观物理和环境演变：一组过渡到POC 和另一个没有的对照组（已关闭）。新的 GOES-16 数据的高时空分辨率允许详细检查该地区 POC 的时间演变。⁴ 公里²，并且通常（88% 的案例）在它们离开 StCu 甲板之前不会重新关闭。观察到大多数 POCs 在夜间形成，并在 StCu 区域收缩时倾向于在白天离开 StCu。相对于 CLOSED 轨迹，POCs 具有系统性更大的有效半径、更低的云滴数浓度、可比的条件云内液态水路径和更高频率的更强烈降水。同时，在 POC 和 CLOSED 轨迹之间没有观察到除边界层高度之外的系统环境差异。有趣的是，两组轨迹之间的再分析气溶胶光学深度没有差异，这可能会导致一种解释，即气溶胶浓度的差异不会影响 POC 的发展或导致大量重新关闭。然而，这在很大程度上取决于对气溶胶-云相互作用的再分析处理，而本研究中使用的产品没有明确处理这些重要过程。这些结果支持了关于降水对 POC 的形成和维持的重要性的共识观点，并证明了现代地球静止遥感数据在评估 POC 生命周期中的效用。