The evolution of anvil clouds detrained from deep convective systems has important implications for the tropical energy balance and is thought to be shaped by radiative heating. We use combined radar‐lidar observations and a radiative transfer model to investigate the influence of radiative heating on anvil cloud altitude, thickness, and microphysical structure. We find that high clouds with an optical depth between 1 and 2 are prevalent in tropical convective regions and can persist far from any convective source. These clouds are generally located at higher altitudes than optically thicker clouds, experience strong radiative heating, and contain high concentrations of ice crystals indicative of turbulence. These findings support the hypothesis that anvil clouds are driven toward and maintained at a preferred optical thickness that corresponds to a positive cloud radiative effect. Comparison of daytime and nighttime observations suggests that anvil thinning proceeds more rapidly at night, when net radiative cooling promotes the sinking of cloud top. It is hypothesized that the properties of aged anvil clouds and their susceptibility to radiative destabilization are shaped by the time of day at which the cloud was detrained. These results underscore the importance of small‐scale processes in determining the radiative effect of tropical convection.

中文翻译：

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热带铁砧云：辐射驱动向首选状态

从深层对流系统减缓下来的铁砧云的演化对热带能量平衡具有重要意义，并被认为是由辐射加热形成的。我们使用雷达雷达观测和辐射传递模型的组合来研究辐射加热对砧云高度，厚度和微物理结构的影响。我们发现光学对流深度在1至2之间的高云在热带对流地区很普遍，并且可以远离任何对流源而持续存在。这些云层通常比光学上较厚的云层位于更高的高度，经受强烈的辐射加热，并且包含指示湍流的高浓度冰晶。这些发现支持了这样的假设，即砧木云被驱向并保持在与正云辐射效应相对应的最佳光学厚度。白天和夜间观察的比较表明，当净辐射冷却促进云顶下沉时，砧座稀疏在夜间进行得更快。假设老化的砧云的性质及其对辐射不稳定的敏感性是由一天中消云的时间决定的。这些结果强调了小规模过程对确定热带对流辐射效应的重要性。假设老化的砧云的性质及其对辐射不稳定的敏感性是由一天中消云的时间决定的。这些结果强调了小规模过程对确定热带对流辐射效应的重要性。假设老化的砧云的性质及其对辐射不稳定的敏感性是由一天中消云的时间决定的。这些结果强调了小规模过程对确定热带对流辐射效应的重要性。