A Modeling Study of Factors that Control the Vigor of Deep Cumulus Convection

深积云对流强度控制因素的模拟研究

• 批准号: 0758550
• 负责人: Francis Robinson
• 金额: $ 37.05万
• 依托单位: Yale University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-06-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0758550&HistoricalAwards=false
• 关键词: Modeling; Study; Factors; Control; Vigor

Observations show substantial variations in the intensity of both tropical and midlatitude-summertime deep convection (e.g., thunderstorm activity) that are not well explained by established measures of the atmosphere's instability based on simple principles. These classic treatments address properties of undiluted parcels of air ascending from a uniformly heated flat surface relative to their surrounding environment to determine the maximum updraft intensity and height achieved by convective clouds. This research will employ model calculations capable of resolving multiple factors influencing such clouds to better understand and quantify the role of variable mid-level atmospheric moisture, heterogeneity in surface heating, and surface orography (i.e. sloped and elevated terrain) in determining their vigor. Resulting improvements in simplified representations of these intricate effects (termed "parameterizations") will ultimately improve global climate models. The primary cloud-resolving numerical system used in this exploration will be the Weather Research and Forecasting (WRF) model, which will be supplemented by more idealized calculations to help understand departures of convective cloud vigor from that predicted by simple parcel theory and to more fully disentangle cause and effect. This strategy will involve carefully designed groups (ensembles) of WRF model runs to systematically explore changes in cloud behavior as a function of key environmental factors. The intellectual merit of this work rests on advancing our basic understanding of moist buoyantly-driven atmospheric convection through a hierarchy of conceptual and numerical models, which will allow researchers to develop and test basic hypotheses concerning factors that control the vigor and heat transport properties of convection, and ultimately the role of such clouds as a form of "turbulence" within the global atmospheric circulation.Broader impacts of this work will include contributions toward more accurate simulations of local/regional weather and global climate, as well as means to more reliably anticipate expected changes in convective activity in the presence of climate change. Training of an undergraduate student in basic elements of design and operation of cloud-resolving models (suitable as an introduction to a chosen career in meteorology for that student) and enhanced exposure of public school students to science through the "DEMOS" program (a Yale University undergraduate organization that does outreach in the surrounding area) will be additional impacts of this effort.

观测显示热带和中纬度夏季深对流的强度有很大的变化（例如，雷暴活动），这是不能很好地解释建立在简单的原则基础上的大气不稳定性的措施。这些经典的处理方法解决了从均匀加热的平坦表面相对于其周围环境上升的未稀释空气包的特性，以确定对流云所达到的最大上升气流强度和高度。这项研究将采用能够解决影响这种云的多个因素的模型计算，以更好地理解和量化可变中层大气湿度，表面加热的异质性和表面地形（即倾斜和高架地形）在确定其活力中的作用。由此产生的对这些复杂影响的简化表示（称为“参数化”）的改进将最终改进全球气候模型。在这次探索中使用的主要的云解析数值系统将是天气研究和预报（WRF）模式，它将由更理想化的计算来补充，以帮助理解对流云活力与简单包裹理论预测的偏离，并更充分地解开因果关系。这一战略将涉及精心设计的WRF模式运行组（集合），以系统地探索云行为的变化作为关键环境因素的函数。这项工作的智力价值在于通过概念和数值模型的层次结构推进我们对潮湿非线性驱动的大气对流的基本理解，这将使研究人员能够开发和测试有关控制对流的活力和热传输特性的因素的基本假设，最终，这种云作为一种“湍流”的形式，这项工作的更广泛影响将包括对更准确地模拟当地/区域天气和全球气候的贡献，以及在气候变化的情况下更可靠地预测对流活动的预期变化的手段。对一名本科生进行云解析模型设计和操作的基本要素培训（适合作为该学生选择气象学职业的入门），并通过“DEMOS”方案（耶鲁大学的一个本科生组织，在周边地区开展外联活动）加强公立学校学生对科学的了解，将是这一努力的额外影响。