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: 1649819
• 负责人: Zhiming Kuang
• 金额: $ 46.13万
• 依托单位: Harvard 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=1649819&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.

湿润对流在云/雨的产生和决定地球的能量平衡和水资源的分布方面起着关键作用。它们在影响环流模式方面也起着关键作用，因此对我们理解和预测天气和气候至关重要。由于这些过程发生在比全球天气和气候模式网格尺寸更小的空间尺度上，它们需要在数值模式中与大尺度流统计相关，或通过参数化表示。参数化的成功需要对湿对流过程的物理基础和过程级的理解。本项目重点研究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，它使空气冷却并增加其密度，使其下沉到表面并作为密度流水平扩散。这些高密度洋流被称为冷池。它们可以引发新的风暴（这是造成暴风雨前阵风和冷空气的原因），改变近地表通量，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明确地解决了冷池和产生它们的过程，并与创新的粒子跟踪一起使用，以揭示导致冷池诞生、演变和消亡的许多因素，以及量化冷池如何改变湿对流的特征，以及如何在全球天气和气候模型中统计地表示这些影响。云和对流仍然是天气和气候预测不确定性的主要来源。通过提高对对流云关键特征的过程级理解和表征，本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之间的合作，培养博士后科学家，并有助于天气和气候模式的发展。

项目成果

Spatial and Temporal Characteristics of Asymmetries in Tropical Cyclones

• DOI: 10.1029/2019gl083179
• 发表时间: 2019-07
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Jia-Chun Guo;Z. Kuang

On Cold Pool Collisions in Tropical Boundary Layers

热带边界层冷池碰撞

• DOI: 10.1029/2018gl080501
• 发表时间: 2019
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Torri, Giuseppe;Kuang, Zhiming
• 通讯作者: Kuang, Zhiming

Why Does Deep Convection Have Different Sensitivities to Temperature Perturbations in the Lower versus Upper Troposphere?

为什么对流层下层和高层的深对流对温度扰动的敏感性不同？

• DOI: 10.1175/jas-d-18-0023.1
• 发表时间: 2019
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Tian, Yang;Kuang, Zhiming
• 通讯作者: Kuang, Zhiming

Linear Stability of Moist Convecting Atmospheres. Part I: From Linear Response Functions to a Simple Model and Applications to Convectively Coupled Waves

• DOI: 10.1175/jas-d-18-0092.1
• 发表时间: 2018-08
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Z. Kuang

The Vertical Momentum Budget of Shallow Cumulus Convection: Insights From a Lagrangian Perspective

浅积云对流的垂直动量收支：拉格朗日视角的见解

• DOI: 10.1029/2018ms001451
• 发表时间: 2019
• 期刊: Journal of Advances in Modeling Earth Systems
• 影响因子: 6.8
• 作者: Tian, Yang;Kuang, Zhiming;Singh, Martin S.;Nie, Ji
• 通讯作者: Nie, Ji