Collaborative Research: Dynamics of Unsaturated Downdrafts, Cold Pools, and Their Roles in Convective Initiation and Organization

合作研究：不饱和下降气流、冷池的动力学及其在对流引发和组织中的作用

• 批准号: 1649770
• 负责人: Pierre Gentine
• 金额: $ 18.97万
• 依托单位: Columbia University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2017
• 资助国家: 美国
• 起止时间: 2017-05-01 至 2021-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1649770&HistoricalAwards=false
• 关键词: Collaborative; Research; Dynamics; Unsaturated; Downdrafts

Moist convections play a critical role in giving rise to clouds/rains and in determining the energy balance of the earth and the distribution of water resources. They also play a key role in forcing the circulation patterns, and thus are central to our understanding and prediction of weather and climate. Because these processes occur at spatial scales smaller than that of the grid sizes of global weather and climate models, they need to be related to large-scale flow statistically in numerical models, or represented by parameterizations. The success of parameterizations demands physically based and process-level understanding of the moist convective processes. This project focuses on one important aspect of moist convections, namely cold pools. When rain evaporates into unsaturated air, it cools the air and increases its density, causing it to sink to the surface and spread out horizontally as a density current. These density currents are known as cold pools. They can trigger new storms (which is responsible for the gusty winds and cooler air that one experiences preceding a storm), modify near-surface fluxes, atmospheric stability, and affect the characteristics and development of convective clouds. In this project, high-resolution numerical simulations that explicitly resolve the cold pools and processes that produce them are used along with innovative particle tracking to unravel the many factors that contribute to the birth, evolution, and demise of cold pools, as well as to quantify how cold pools modify the characteristics of moist convections and how to represent these effects statistically in global models of weather and climate.Clouds and convection remain major sources of uncertainty in weather and climate predictions. By improving process-level understanding and representation of a key feature of convective clouds, this research will help reduce such uncertainties. This research will also strengthen collaboration between university scientists and train postdoctoral scientists, and contribute to the development of weather and climate models.

潮湿的对流在产生云/雨水以及确定地球的能量平衡和水资源分布方面起着至关重要的作用。它们在迫使循环模式方面也起着关键作用，因此对于我们对天气和气候的理解和预测至关重要。由于这些过程发生在比全局天气和气候模型的网格大小的空间尺度上发生，因此它们需要与数值模型统计上的大规模流量相关，或者由参数化表示。参数化的成功需要基于身体的和过程级别对湿对流过程的理解。该项目着重于潮湿对流的一个重要方面，即冷池。当雨水蒸发到不饱和的空气中时，它会冷却空气并增加其密度，从而使其下沉到表面并作为密度电流水平散布。这些密度电流称为冷池。它们可以触发新的风暴（这是一个在风暴之前经历的阵风和较冷的空气），修改近地面通量，大气稳定性，并影响对流云的特征和发展。 在这个项目中，高分辨率的数值模拟可以明确解决产生它们的冷水池和过程以及创新的粒子跟踪，以揭示有助于造成出生，进化和降临的许多因素和气候预测。通过提高过程级别的理解和对流云的关键特征的表示，这项研究将有助于减少这种不确定性。这项研究还将加强大学科学家与培训博士后科学家之间的合作，并为天气和气候模型的发展做出贡献。