In order to improve the physical consistency between shallow and deep convection, we modify the deep convective closure in the Community Atmosphere Model version 5 (CAM5) coupled with a third‐order turbulence closure parameterization (i.e., Cloud Layers Unified by Binormals [CLUBB]). The revised closure reserves a portion of the total convective available potential energy for shallow convection via utilizing the heating and moistening profiles from CLUBB to distribute moisture and energy between shallow and deep convection. Simulations at two resolutions (i.e., 2° and 0.5°, respectively) are conducted to investigate the impacts of convective closure on the simulated precipitation diurnal variations. Results from low‐resolution simulations show that the revised closure suppresses deep convection until the lower troposphere is sufficiently moistened by shallow convection, which improves the precipitation diurnal variation simulations compared with the default closure, with the precipitation diurnal peak over tropical lands delayed from 12LST to 19LST. The revised closure better simulates the diurnal variations for precipitation over the Asian monsoon region, such as the delayed precipitation onset, but still fails to well capture the nighttime peak for precipitation there. This deficiency is alleviated to some extent when applying the revised closure in high‐resolution simulations, but nighttime precipitation is still underestimated probably because key processes responsible for nighttime convection are missing. Overall, our results indicate that establishing the consistency between shallow and deep convection is critical for the precipitation diurnal cycle simulations.

中文翻译：

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结合CLUBB的社区大气模型第5版中模拟的降水量日变化与深对流封闭关系的浅层对流

为了提高浅对流与深对流之间的物理一致性，我们修改了社区大气模型版本5（CAM5）中的深对流封闭，并结合了三阶湍流封闭参数化（即，由Binormals统一的云层[CLUBB]） 。修订后的封闭装置利用CLUBB的加热和润湿曲线在浅层和深层对流之间分配水分和能量，从而为浅层对流保留了全部对流可用势能的一部分。进行了两种分辨率（分别为2°和0.5°）的模拟，以研究对流封闭对模拟降水日变化的影响。低分辨率模拟的结果表明，修正的封闭措施抑制了深对流，直到低层对流层被浅对流充分润湿为止，与默认封闭措施相比，这改善了降水日变化模拟，热带土地上的降水日峰值从12LST延迟至19LST。修改后的封闭能更好地模拟亚洲季风区域降水的昼夜变化，例如延迟的降雨开始，但仍无法很好地捕捉夜间降水的高峰。在高分辨率模拟中应用修订后的封闭方法后，这种缺陷在一定程度上得到了缓解，但是夜间降水仍然被低估了，这可能是因为缺少负责夜间对流的关键过程。总体，