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Abstract

Using highly resolved large-eddy simulations on two different domain sizes, we investigate the influence of precipitation and spatial organization on the thermodynamic structure of the trade-wind layer, under a uniform 4K warming at constant relative humidity. In non-precipitating simulations the increased surface latent heat flux in the warmer climate produces a deeper and drier cloud layer with reduced cloud fractions between 1.5 and 4km. Precipitation prevents the deepening and drying of the cloud layer in response to warming. Cloud fractions still decrease in the upper cloud layer, because stratiform outflow layers near cloud tops are less pronounced and because the larger liquid water contents are confined to narrower updrafts. Simulations on a sixteen-fold larger domain lead to the spatial organization of clouds into larger and deeper cloud clusters. The presence of deeper clouds results in a shallower, warmer and drier trade-wind layer, with strongly reduced cloud cover. The warming response in the precipitating large-domain simulation nevertheless remains similar to the small-domain precipitating simulation. On the large domain, deeper clouds can also develop without precipitation, because moisture-convection feedbacks strengthen in the absence of cold-pool dynamics. Overall, total cloud cover and albedo decrease only slightly with warming in all cases. This demonstrates the robustness of shallow cumuli—in particular of cloud fraction near the lifting condensation level—to changes in the large-scale environment. This article is protected by copyright. All rights reserved.