EAGER: Development of a Bulk-Emulating Microphysics Scheme

数值天气和气候模式使用云微物理方案来表示大量云粒子的生长，相互作用和衰减。 对云的全部特征（如不同颗粒大小的分布）进行显式建模，对于大多数目的来说，在计算上是不可行的，因此研究人员设计了可以准确表示对模型重要的某些量的方案。 然而，有一些工艺在很大程度上取决于颗粒尺寸分布等方面，因此，更好地理解这两种方法之间的差异将有助于识别问题。 这项工作将创建一个云方案，是基于显式云建模，但可比较的计算不太先进的计划，以便可以进行直接比较。 主要的社会影响将是对天气和气候模型的下游影响。 本计画亦提供一位研究生的训练，目的在发展一个模拟体块的微观物理方案。 有两种常见的微观物理方案，明确预测颗粒尺寸分布的箱方案，以及预测颗粒尺寸分布的1-3个整数的散装方案。 BIN方案在计算上是昂贵的，并且不适用于全球气候模式。 然而，科学界最近提出，批量方案不能正确地表示气溶胶-云的相互作用。 该项目将开发一种工具和方法，用于测试体微物理方案的概念和数值限制，最终目标是告知社区未来应如何设计新方案。该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的知识价值和更广泛的影响审查标准进行评估来支持。

Numerical weather and climate models use cloud microphysical schemes to represent how a large collection of cloud particles grow, interact, and decay. Explicitly modeling the full characteristics of a cloud, such as the distribution of different particle sizes, is not computationally feasible for most purposes, so researchers have devised schemes that can accurately represent certain quantities that are important for the models. However, there are some processes that depend greatly on aspects such as the particle size distribution, so having an improved understanding of the differences between the two approaches would be useful to identify problems. This work will create a cloud scheme that is based upon explicit cloud modeling but is comparable to the less computationally advanced schemes so that direct comparisons can be conducted. The main societal impact would be the downstream effect on weather and climate models. The project also provides training for a graduate student.This project aims to develop a bulk-emulating microphysics scheme. There are two common classes of microphysics schemes, the bin scheme where the particle size distribution is explicitly predicted, and the bulk scheme where 1-3 integral quantities of the particle size distribution are predicted. Bin schemes are computationally expensive and not feasible for use in global climate models. However, it has been recently suggested by the scientific community that bulk schemes are incapable of properly representing aerosol-cloud interactions. This project will develop a tool and method for testing the conceptual and numerical limitations of bulk microphysics schemes with an end goal of informing the community how new schemes should be designed in the future.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.