RII Track-4: Turbulence Effects on Cloud Microphysical Processes: Development and Testing of Subgrid-Scale Parameterizations for Large Eddy Simulation

云在地球系统的许多过程中起着关键作用，包括降水、大气化学和气候。在过去的几十年里，科学家们已经证明，云内的湍流会导致湿度、温度和水滴浓度的大幅波动，这直接影响云的寿命和降雨的形成。尽管小尺度云湍流很重要，但很少有研究关注如何在用于研究和天气预报的计算机模型中表示其影响。在这个项目中，首席研究员（PI）将与密歇根理工大学（MTU）的专家合作开发模型，准确地代表计算机模型中小规模云湍流的影响。为了实现这一目标，PI和一名研究生将在MTU云室中进行实验室实验，MTU云室是美国唯一能够在受控实验室环境中创建和维持湍流云的湍流室。这笔资金将建立PI和主机之间的持久合作，并将通过提供独特的实验室设施来支持研究生的教育。通过扩大PI的专业知识，包括实验室实验和云湍流，该项目将使PI和国家气象中心的合作伙伴之间的未来合作，从而加强中央俄克拉荷马州气象企业的整体竞争力。湍流是云混合和夹带的关键驱动力，导致温度，湿度，云粒子浓度的显着波动，以及碰撞或分裂。最近的研究表明，过饱和的湍流波动会导致云滴尺寸分布的扩大，引发降雨的速度比理论预测的静止环境要快得多。随着计算能力的提高，大涡模拟（LES），它直接解决了最大尺度的湍流，正在成为一个有前途的技术，天气预报和研究湍流，微物理和大尺度云特性之间的联系。该项目旨在开发新的亚网格尺度模型，可以准确地代表小尺度湍流波动的过饱和大涡模拟。PI和一名研究生将与密歇根理工大学的主持人合作，在MTU云室中进行实验，在那里可以通过潮湿的Rayleigh-Benard对流产生稳态湍流云。将进行一系列实验室实验，以调查空间和时间尺度上的过饱和波动分布，并开发新的模型，仅根据流动的分辨率尺度特征的知识，即可恢复亚网格过饱和方差。该项目将使PI在实验室实验和云湍流方面发展研究专业知识，从而使未来与国家气象中心的合作伙伴进行合作成为可能。该项目支持的未来研究领域具有显着的社会效益，包括改进降水预报和雷达测量，以及提高对云在地球现状和气候中的作用的了解。该奖项反映了NSF的法定使命，并且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，被认为值得支持。

Clouds play a critical role for many processes in the Earth system, including precipitation, atmospheric chemistry, and climate. Over the past few decades, scientists have shown that turbulence within clouds can cause large fluctuations in humidity, temperature, and water droplet concentrations, which directly impact cloud lifetimes and rain formation. Despite the importance of small-scale cloud turbulence, few studies have focused on how to represent its effects in computer models used for research and weather forecasting. In this project, the Principal Investigator (PI) will partner with experts at Michigan Technological University (MTU) to develop models that accurately represent the effects of small-scale cloud turbulence in computer models. In order to achieve this goal, the PI and a graduate student will perform laboratory experiments in the MTU cloud chamber, the nation's only turbulence chamber capable of creating and sustaining turbulent clouds in a controlled laboratory environment. This funding will establish a lasting collaboration between the PI and hosts and will support the education of a graduate student by providing access to unique laboratory facilities. By expanding the PI's expertise to encompass laboratory experiments and cloud turbulence, this project will enable future collaborations between the PI and partners in the National Weather Center, thereby strengthening the overall competitiveness of the Central Oklahoma weather enterprise.Turbulence is a key driver of cloud mixing and entrainment, causing significant fluctuations in temperature, humidity, cloud particle concentrations, and collisions or breakup. Recent studies have demonstrated that turbulent fluctuations of supersaturation can lead to a broadening of the cloud droplet size distribution, initiating rain formation significantly faster than what theory predicts for a quiescent environment. As computational power increases, large eddy simulation (LES), which directly resolves the largest scales of turbulence, is becoming a promising technique for both weather forecasting and for studying the linkages between turbulence, microphysics, and large-scale cloud properties. This project aims to develop new subgrid-scale models that can accurately represent small-scale turbulent fluctuations of supersaturation in LES. The PI and a graduate student will partner with hosts at Michigan Technological University to perform experiments in the MTU cloud chamber, where steady-state turbulent clouds can be produced through moist Rayleigh-Benard convection. An ensemble of laboratory experiments will be performed to investigate the distribution of supersaturation fluctuations across spatial and temporal scales, and to develop new models that can recover the subgrid supersaturation variance based only on knowledge of resolved-scale features of the flow. This project will allow the PI to develop research expertise in laboratory experiments and cloud turbulence, thereby enabling future collaborations with partners in the National Weather Center. The future research areas enabled by this project have significant societal benefits, including improved precipitation forecasts and radar measurements, and an improved understanding of the role of clouds in Earth's present and climate.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.