We present nonrotating simulations with the Goddard Earth Observing System (GEOS) atmospheric general circulation model (AGCM) in a square limited area domain over uniform sea surface temperature. As in previous studies, convection spontaneously aggregates into humid clusters, driven by a combination of radiative and moisture‐convective feedbacks. The aggregation is qualitatively independent of resolution, with horizontal grid spacing from 3 to 110 km, with both explicit and parameterized deep convection. A budget for the spatial variance of column moist static energy suggests that longwave radiative and surface flux feedbacks help establish aggregation, while the shortwave feedback contributes to its maintenance. Mechanism‐denial experiments confirm that aggregation does not occur without interactive longwave radiation. Ice cloud radiative effects help support the humid convecting regions but are not essential for aggregation, while liquid clouds have a negligible effect. Removing the dependence of parameterized convection on tropospheric humidity reduces the intensity of aggregation but does not prevent the formation of dry regions. In domain sizes less than (5,000 km)², the aggregation forms a single cluster, while larger domains develop multiple clusters. Larger domains initialized with a single large cluster are unable to maintain them, suggesting an upper size limit. Surface wind speed increases with domain size, implying that maintenance of the boundary layer winds may limit cluster size. As cluster size increases, large boundary layer temperature anomalies develop to maintain the surface pressure gradient, leading to an increase in the depth of parameterized convective heating and an increase in gross moist stability.

中文翻译：

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有限区域AGCM中的非旋转对流自聚集

我们在均匀海面温度的正方形有限区域域内，使用戈达德地球观测系统（GEOS）大气总环流模型（AGCM）提出了非旋转模拟。与以前的研究一样，对流在辐射和水分对流反馈的共同作用下自发地聚集为潮湿的团簇。该集合在质量上与分辨率无关，水平网格间距为3至110 km，同时具有显式和参数化深对流。柱湿静态能量的空间变化预算表明，长波辐射和表面通量反馈有助于建立聚集，而短波反馈则有助于维持聚集。否定机制的实验证实，没有相互作用的长波辐射，不会发生聚集。冰云的辐射效应有助于支撑潮湿的对流区域，但对于聚集而言并非必不可少，而液态云的辐射效应可忽略不计。消除参数化对流对流层湿度的依赖性可降低聚集强度，但不会阻止形成干燥区域。在小于（5,000 km）的域中^{如图2所示}，聚合形成单个群集，而较大的域则形成多个群集。使用单个大型群集初始化的较大域无法维护它们，这表明存在上限。地表风速随域大小而增加，这意味着边界层风的维持可能会限制簇的大小。随着团簇尺寸的增加，边界层温度将出现较大的异常现象，以维持表面压力梯度，从而导致对流加热参数化深度的增加以及总湿润稳定性的增加。