The Poloidal Convection Model and Multi-Scale Moist Circulations

极向对流模型和多尺度湿环流

• 批准号: 2224293
• 负责人: Matthew Igel
• 金额: $ 39.99万
• 依托单位: University of California-Davis
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2022
• 资助国家: 美国
• 起止时间: 2022-08-01 至 2025-07-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2224293&HistoricalAwards=false
• 关键词: Poloidal; Convection; Model; Multi; Scale

Tall cumulus clouds produce most heavy rains globally. They form as air rises from near the surface to the upper reaches of the atmosphere. To make room for the ascending, moisture-laden air, cool, dry air is forced downward around the cloud. The ascending air forms visible cloud droplets and rain drops within it, but the descending air is largely invisible and may extend to distances far away from the cloudy core. The importance of this pairing of ascent and descent to the behavior of cloud is appreciated, but it is not well described. Current models and descriptions of raining convective clouds focus on the air that ascends inside the cloud and greatly simplify the descending portion. The project aims to remedy this by incorporating both ascending and descending air in one framework. By doing so, it will be possible to understand some observed behavior of convective clouds for the first time. For example, the project aims to mathematically describe how tall convective clouds interact with one another through their three-dimensional flow and thus how individual clouds coalesce to form heavily raining, long-lived weather systems and to better understand why and when certain shaped clouds grow and why others do not. This understanding will then be incorporated into a model to assess and forecast global precipitation patterns and behavior. The project will also train students at various levels in interdisciplinary research. The project will test and further develop a new model that describes an arbitrary convective circulation as poloidal. The poloidal model will be contrasted with a plume model. By coupling convective ascent and descent with a smoothly varying complete velocity field, the project will develop descriptions of dynamical aspects of clouds and circulation such as how advection and diffusion affect growth and decay of circulations, how pairs of circulations interact, and how localized latent heating within updrafts contributes to spinning up or down the return circulation. By simultaneously incorporating dynamical aspects of poloidal circulations into a simple model, it will be possible to address long standing questions like how individual convective circulations feed upscale to synoptic ones like the Madden Julian Oscillation.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.

高积云产生全球最多的暴雨。 当空气从地表附近上升到大气上游时，它们就形成了。 为了给上升的、充满湿气的空气腾出空间，凉爽、干燥的空气被迫在云层周围向下流动。 上升的空气在其中形成可见的云滴和雨滴，但下降的空气基本上是不可见的，并且可能延伸到远离云核的距离。 人们认识到这种上升和下降配对对云行为的重要性，但还没有得到很好的描述。 当前对流雨对流云的模型和描述集中于云内上升的空气，并大大简化了下降部分。 该项目旨在通过将上升和下降空气合并在一个框架中来解决这一问题。 通过这样做，将有可能首次了解对流云的一些观测到的行为。 例如，该项目旨在以数学方式描述高对流云如何通过三维流相互作用，从而描述单个云如何结合形成大雨、长期的天气系统，并更好地理解某些形状的云生长的原因和时间以及为什么其他人不这样做。 然后，这种理解将被纳入一个模型中，以评估和预测全球降水模式和行为。 该项目还将培训不同级别的学生进行跨学科研究。该项目将测试并进一步开发一种将任意对流环流描述为极向的新模型。 极向模型将与羽流模型进行对比。 通过将对流上升和下降与平滑变化的完整速度场耦合起来，该项目将开发对云和环流动力学方面的描述，例如平流和扩散如何影响环流的增长和衰减、环流对如何相互作用以及局部潜热如何在上升气流内有助于旋转向上或向下的返回循环。 通过同时将极向环流的动力学方面纳入一个简单的模型，将有可能解决长期存在的问题，例如单个对流环流如何将高级的对流环流提供给像马登朱利安振荡这样的天气环流。该奖项反映了 NSF 的法定使命，并被认为是值得的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来提供支持。