Physical mechanisms that are key to observed convective clustering in 2‐day rain events are examined. Previous analysis of the 2‐day rain events during the Atmospheric Radiation Measurement Madden‐Julian Oscillation Investigation Experiment (AMIE)/Dynamics of the Madden‐Julian Oscillation (DYNAMO) field campaign data revealed two distinct phases of convective clustering. Using a cloud‐system‐resolving model, we perform a series of intervention experiments to investigate the underlying mechanisms for convective clustering in each phase. In the developing phase, in addition to previously emphasized processes such as the cold pool‐updraft interaction and moisture‐convection feedbacks, our results show that the vertical wind shear in the lower free troposphere is a critical factor for convective clustering. Stronger lower free‐tropospheric wind shear increases the entrainment of environmental air into updrafts and prevents convective clouds from being omnipresent. This result suggests that stronger vertical wind shear in the lower free troposphere can help spatially organize the convection, even for non–squall‐line‐type convective systems. In the decaying phase, the cold pool‐updraft interaction becomes less effective in aggregating convective clouds because the boundary layer is widely cooled by stratiform precipitation. Instead, the mesoscale downdraft driven by the stratiform precipitation becomes the dominant factor to maintain the relatively aggregated convection. Additionally, removing horizontal variations in radiative heating has no impact on convective clustering on this 2‐day time scale, even in the decaying phase when stratiform clouds are widespread. The implication of these results for improving the representation of mesoscale convective organization in convection schemes is discussed.

中文翻译：

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AMIE / DYNAMO中为期2天的降雨事件中的对流聚集机制

研究了在2天的降雨事件中观察到的对流聚集的关键物理机制。对大气辐射测量Madden-Julian振荡调查实验（AMIE）/ Dynamics of Madden-Julian振荡动态（DYNAMO）野外运动数据进行的前两天降雨事件的先前分析显示，对流聚类分为两个不同的阶段。使用云系统解析模型，我们执行了一系列干预实验，以研究每个阶段对流聚类的潜在机制。在开发阶段，除了以前强调的过程（如冷池-上升气流相互作用和水分对流反馈）外，我们的结果表明，较低对流层中的垂直风切变是对流聚类的关键因素。较低的对流层较低的强风切变增加了环境空气进入上升气流的速度，并防止对流云无处不在。该结果表明，即使在非s线型对流系统中，对流较低层的垂直风切变较强，也有助于对流的空间组织。在衰减阶段，由于边界层被层状降水广泛冷却，冷池-上升气流的相互作用在聚集对流云时变得不太有效。取而代之的是，由层状降水驱动的中尺度下降气流成为维持相对聚集对流的主要因素。此外，在这2天的时间范围内，消除辐射热量的水平变化对对流星团没有影响，即使在层状云广泛分布的衰减阶段。讨论了这些结果对改进对流方案中中尺度对流组织的表示的意义。