近日，成都信息工程大学Xianyu Yang及其课题组成员在研究深层云垂直结构和尺寸分布的大涡模拟中取得新成果。这一研究成果发表在2023年12月12日出版的国际学术期刊《大气科学进展》上。

为了填补这一知识空白，研究进行了全面的大涡模拟(LES)，并对陆地区域进行了对比分析。研究结果表明，云的形成遵循伯努利试验的原则，说明幂律标度保持一致，无论云大小和云数量之间存在固有的深层云属性。这种缩放模式包括液体、冰和深层云中的混合相。但表征深层云中，云的尺度和数量之间相互作用的指数，特别是对于液体、冰或混合相云，类似于浅对流的指数，收敛接近于零。

这种收敛表明深层云中云的数量和大小有减小的趋势。值得注意的是，低层大气中大量水汽的注入和凝结潜热的释放起到了重要作用。然而，这种作用对冰相的形成是有限的。深层云中液相和冰相的出现受到潜热的促进和中层固有风切变的影响。这些相互关系在制定参数化和后处理模型结果中具有潜在的应用价值。

据研究人员介绍，在以离散云尺寸分布(CSD)为特征的对流方案中，假设的横向混合速率与卷流尺寸的指数系数成反比。遵循了典型假设，但它也揭示了特别是对于深层云的固有的不确定性。

附：英文原文

Title: Large eddy simulation of vertical structure and size distribution of deep layer clouds

Author: Bangjun Cao, Xianyu Yang, JUN WEN, Qin Hu, Ziyuan Zhu

Issue&Volume: 2023-12-12

Abstract: In a convective scheme featuring a discretized Cloud Size Distribution (CSD), the assumed lateral mixing rate is inversely proportional to the exponential coefficient of plume size. This follows a typical assumption of -1, but it has unveiled inherent uncertainties, especially for deep layer clouds. Addressing this knowledge gap, we conducted comprehensive large eddy simulations (LES) and conducted comparative analyses focused on terrestrial regions. Our investigation has illuminated that cloud formation adheres to the tenets of Bernoulli trials, illustrating power-law scaling that remains consistent regardless of the inherent deep layer cloud attributes existing between cloud size and the number of cloud. This scaling paradigm encompasses liquid, ice, and mixed-phase in deep layer clouds. The exponent characterizing the interplay between cloud scale and number in the deep layer cloud, specifically for liquid, ice, or mixed-phase clouds, resembles that of shallow convection, but converges closely to zero. This convergence signifies a propensity for diminished cloud numbers and sizes within deep layer clouds. Notably, the infusion of abundant moisture and the release of latent heat by condensation within the lower atmospheric strata make substantial contributions. However, this role on ice phase formation is limited. The emergence of liquid and ice phases in deep layer clouds is facilitated by the latent heat and influenced by the wind shear inherent in the mid-levels. These interrelationships hold potential applications in formulating parameterizations and post-processing model outcomes.

DOI: 10.1007/s00376-023-3134-2

Source: http://www.iapjournals.ac.cn/aas/en/article/doi/10.1007/s00376-023-3134-2viewType=HTML