Descriptions of cloud ensembles in radiative convective equilibrium (RCE) rely mostly on the assumption that clouds are randomly distributed in space, a hypothesis that obviously fails in presence of strong organization. In this work, idealized RCE simulations at horizontal grid spacings ranging from 2 km to 125 m are analyzed, displaying a transition between complete randomness at coarse resolution to a high degree of cold pool driven organization at high resolution. The objective is then twofold: (a) characterizing the spatial cloud patterns focusing on correlation scales and association with covariates; (b) providing a statistical description of organized cloud ensembles to generalize existing theories based on complete randomness. It is demonstrated that organized cloud ensembles may be treated as heterogeneous point processes where individual clouds do not interact substantially with their neighbors. In other words, clouds may be considered as randomly distributed if we restrict the space to regions of high cloud density. In addition, it is shown that in highly organized situations local cloud counts may be modeled using negative binomial distributions, while cloud mass fluxes follow lognormal distributions. The total mass flux within regions of varying sizes can then be predicted by compounding the two aforementioned distributions. The total mass flux variability at scales ≲5 km is dominated by the heavy-tails of the mass flux distributions, whereas at scales ≳5 km, it is entirely controlled by the spatial cloud count variability (the spatial cloud pattern). These results have important implications for the parameterization of organized convection in quasi-equilibrium.

中文翻译：

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辐射对流平衡中有组织的积云系团的空间弥散和统计描述

辐射对流平衡（RCE）中云系群的描述主要依赖于云在空间中随机分布的假设，这种假设在存在强组织的情况下显然会失败。在这项工作中，分析了水平网格间距范围从 2 km 到 125 m 的理想化 RCE 模拟，显示了粗分辨率下的完全随机性到高分辨率下的高度冷池驱动组织之间的过渡。那么目标是双重的：（a）表征空间云模式，重点关注相关尺度和与协变量的关联； (b) 提供有组织的云集合的统计描述，以概括基于完全随机性的现有理论。结果表明，有组织的云集合可以被视为异构点过程，其中各个云不会与其邻居发生实质性交互。换句话说，如果我们将空间限制在云密度高的区域，则云可以被认为是随机分布的。此外，结果表明，在高度组织化的情况下，局部云计数可以使用负二项式分布进行建模，而云质量通量遵循对数正态分布。然后可以通过复合上述两个分布来预测不同尺寸区域内的总质量通量。 ≲5 km尺度上的总质量通量变化主要由质量通量分布的重尾部分主导，而在≳5 km尺度上，它完全由空间云计数变化（空间云模式）控制。这些结果对于准平衡条件下有组织对流的参数化具有重要意义。