AMPlifying the Simulation of Clouds and Precipitation

在天气和气候模式中，正确地模拟云对于准确预测云和降雨至关重要。在大气模式中，有两种常见的方式来表示小规模的云过程；它们被称为面元微物理方案和大体积微物理方案。批量模式是简单的模式，执行速度很快，而仓位模式要复杂得多，但运行速度很慢--事实上，速度太慢，不能用于天气预报或气候预测。这个项目将使用一种新的模型，称为任意矩预测器(AMP)，该模型受益于BIN方案的准确性和灵活性来改进整体方案。AMP起镜头的作用。它允许天气模型将垃圾箱方案视为批量方案。通过改变观点，将有可能第一次了解如何最好地在模型中实现批量方案。这一结果有可能导致未来天气和气候模式的设计和开发发生重大变化。AMP像现有的整体方案一样预测云滴和雨滴的尺寸分布矩，但过程参数化与BIN方案使用的相同。它是灵活的，因为它可以预测质量混合比和一个或两个额外的任意分布力矩。这项工作将分为两个主要部分。1)对两种BIN方案和每种BIN方案对应的两个AMP版本的暖相层积云的大涡模拟进行了比较，以评估总体方案的基本局限性。在垃圾桶方案和散装方案之间进行如此直接的比较以前是不可能的。2)将使用AMP和预测力矩的替代组合运行额外的模拟。模拟将与现有的观测进行严格的评估，以探索使用非标准矩组合来改进云和降水模拟的可能性。这种可能性是基于观察证据提出的，但尚未在3D模拟中进行测试。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Properly simulating clouds is critical for accurate prediction of clouds and rainfall in weather and climate models. There are two common ways in which small-scale cloud processes are represented in atmospheric models; these are known as bin microphysics schemes and bulk microphysics schemes. Bulk schemes are simple models that execute quickly while bin schemes are much more complex but run slowly – in fact, too slowly to be used in weather forecasting or climate prediction. This project will use a new model, called the Arbitrary Moment Predictor (AMP), which benefits from the accuracy and flexibility of bin schemes to improve bulk schemes. AMP acts as a lens. It allows a weather model to see a bin scheme as though it were a bulk scheme. By changing the view, it will become possible to understand how best to implement bulk schemes in models for the first time. The results have the potential to lead to a major shift in the design and development of future weather and climate models.AMP predicts size distribution moments of cloud droplets and rain drops like existing bulk schemes, but the process parameterizations are identical to those used by a bin scheme. It is flexible in that it can predict mass mixing ratio and one or two additional arbitrary distribution moments. There will be two major parts of the work. 1) Large eddy simulations of warm phase stratocumulus clouds with two bin schemes and with two versions of AMP corresponding to each bin scheme will be compared to assess fundamental limitations of bulk schemes. Such a direct comparison between bin and bulk schemes has not been possible before. 2) Additional simulations will be run using AMP with alternative combinations of predicted moments. Simulations will be rigorously assessed with available observations to explore the possibility that nonstandard moment combinations should be used to improve simulation of clouds and precipitation. Such a possibility has been suggested based on observational evidence but has not been tested in 3D simulations.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.