AGS-PRF: Modeling Ice Crystal Habit Evolution from Vapor Growth and Riming--Investigating How Evolving Ice Particle Properties Impacts Clouds, Precipitation, and Phase Partitioning

AGS-PRF：模拟蒸汽生长和沸腾的冰晶习性演化——研究演化的冰粒特性如何影响云、降水和相分配

• 批准号: 1524267
• 负责人: Anders Jensen
• 金额: $ 8.6万
• 依托单位: Jensen Anders
• 依托单位国家: 美国
• 项目类别: Fellowship Award
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-04-01 至 2018-03-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1524267&HistoricalAwards=false
• 关键词: AGS; PRF; Modeling; Ice; Crystal

Representing ice in microphysics models is important not only to study the effects of ice on cloud dynamics and cloud lifetime, but also for accurate quantitative precipitation forecasts. Traditional microphysics parameterizations artificially separate ice into categories such as cloud ice, snow, and graupel. These models assume that for each category ice crystal size varies with mass, but they do not account for ice crystal shape evolution. In nature, ice crystal shape, or habit, is temperature dependent and evolves as ice moves through a cloud. Ice crystal shape significantly affects vapor growth rates by varying the gradients in the encompassing vapor field. Ice crystal shape also influences riming rates and fall speed. Traditional models are not able to capture this ice crystal shape sensitivity.This project will study the impact of ice crystal shape evolution on different cloud systems. Simulations will be conducted using the Weather Research and Forecasting (WRF) model to look at how ice crystal habit evolution impacts orographic precipitation, tropical cyclone dynamics and precipitation, and squall lines. A 2-dimensional modeling framework will also be used to explore the effects of evolving ice crystal shape on phase partitioning in mixed-phase clouds. Finally, how representing lightly-rimed ice crystals, which is now possible by evolving ice crystal shape, impacts mixed-phase cloud stability will be studied. Intellectual Merit:The research provides a unique opportunity to study how ice crystal habit evolution impacts different cloud systems. At present, the degree to which ice particle shape evolution influences cloud evolution is unknown. With the new microphysics parameterization, the influence evolving ice crystal shape has on cloud system properties can be explored. How light riming affects mixed-phase clouds can also be examined for the first time.Broader Impacts:Modeling ice crystal fall speed evolution which is partially determined by ice crystal shape is crucial for quantitative precipitation forecasts. Also, cirrus cloud properties and lifetime are incredibly sensitive to ice crystal fall speeds. Cirrus cloud radiative properties depend on ice crystal shape as well, meaning ice crystal shape could have important influences on climate. Because the microphysical methods in this study can, in principle, be used in any modeling framework, the research has the potential to impact modeling ranging from operational forecasting through climate studies of ice clouds. Being able to more accurately forecast precipitation, especially heavy or persistent precipitation that could cause flooding in general makes this research relevant to society.

在微物理模型中表示冰不仅对于研究冰对云动力学和云寿命的影响很重要，而且对于准确定量降水预报也很重要。 传统的微物理参数化人为地将冰分为云冰、雪和霰等类别。这些模型假设每个类别的冰晶尺寸随质量而变化，但它们没有考虑冰晶形状的演化。在自然界中，冰晶的形状或习惯取决于温度，并随着冰在云中移动而演变。 冰晶形状通过改变周围蒸汽场的梯度来显着影响蒸汽生长速率。冰晶形状也会影响起泡速率和下降速度。 传统模型无法捕捉这种冰晶形状敏感性。该项目将研究冰晶形状演化对不同云系统的影响。 将使用天气研究和预报（WRF）模型进行模拟，以了解冰晶习性演化如何影响地形降水、热带气旋动态和降水以及飑线。 二维建模框架还将用于探索不断变化的冰晶形状对混合相云中相分配的影响。 最后，将研究如何通过演化冰晶形状来表示浅边缘冰晶对混合相云稳定性的影响。 智力价值：这项研究提供了一个独特的机会来研究冰晶习性演化如何影响不同的云系统。 目前，冰粒形状演化对云演化的影响程度尚不清楚。通过新的微物理参数化，可以探索不断变化的冰晶形状对云系统特性的影响。 还首次研究了光亮如何影响混合相云。更广泛的影响：对冰晶坠落速度演化进行建模（部分由冰晶形状决定）对于定量降水预报至关重要。 此外，卷云的特性和寿命对冰晶坠落速度非常敏感。卷云的辐射特性也取决于冰晶形状，这意味着冰晶形状可能对气候产生重要影响。 由于本研究中的微物理方法原则上可以用于任何建模框架，因此该研究有可能影响从业务预测到冰云气候研究的建模。 能够更准确地预测降水，尤其是可能导致洪水的强降水或持续降水，使得这项研究与社会相关。