This study investigates the direct radiative-convective processes that drive and maintain aggregation within convection-permitting elongated channel (and smaller square) simulations of the UK Met Office Unified Model. Our simulations are configured using three fixed sea surface temperatures (SSTs) following the Radiative-Convective Equilibrium Model Intercomparison Project (RCEMIP) protocol. By defining cloud types based on the profile of condensed water, we study the importance of radiative interactions with each cloud type to aggregation. We eliminate the SST dependence of the vertically integrated frozen moist static energy (FMSE) variance budget framework by normalizing FMSE between hypothetical upper and lower limits based on SST. The elongated channel simulations reach similar degrees of aggregation across SSTs, despite shortwave and longwave interactions with FMSE contributing less to aggregation as SST increases. High-cloud longwave interactions are the main drivers and maintainers of aggregation. Their influence decreases with SST as high clouds become less abundant. This SST dependence is consistent with changes in grid spacing and the critical humidity threshold for condensation (RHcrit). However, the domain-mean longwave-FMSE feedback would likely decrease as grid spacing and RHcrit are reduced by lowering the condensed water path and cloud top height of high-cloud, and altering the distribution of different cloud types. Shortwave interactions with water vapor are key maintainers of aggregation and are dependent on SST and the degree of aggregation itself. The analysis method used provides a new framework to compare the effects of radiative-convective processes on self-aggregation across different SSTs and model configurations to help improve our understanding of self-aggregation.

中文翻译：

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云辐射相互作用及其对对流自聚集的贡献

这项研究调查了在英国气象局统一模型的允许对流的细长通道（和较小的正方形）模拟中驱动和维持聚集的直接辐射对流过程。我们的模拟是根据辐射-对流平衡模型比对项目 (RCEMIP) 协议使用三个固定海面温度 (SST) 进行配置的。通过根据冷凝水的剖面定义云类型，我们研究了与每种云类型的辐射相互作用对聚集的重要性。我们通过基于 SST 对假设上限和下限之间的 FMSE 进行归一化，消除了垂直整合冷冻湿静态能量 (FMSE) 方差预算框架的 SST 依赖性。延长的通道模拟在 SST 之间达到了相似的聚合程度，尽管随着 SST 增加，短波和长波与 FMSE 的相互作用对聚集的贡献较小。高云长波交互是聚合的主要驱动力和维护者。随着高云变得不那么丰富，它们的影响会随着海温而降低。这种 SST 依赖性与网格间距和凝结的临界湿度阈值 (RHcrit) 的变化一致。然而，域均值长波-FMSE 反馈可能会随着网格间距和 RHcrit 通过降低高云的凝聚水路径和云顶高度以及改变不同云类型的分布而减小。与水蒸气的短波相互作用是聚集的关键维持因素，取决于 SST 和聚集程度本身。