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.

潮湿对流在产生云/雨以及确定地球能量平衡和水资源分布方面发挥着关键作用。它们还在影响环流模式方面发挥着关键作用，因此对于我们理解和预测天气和气候至关重要。由于这些过程发生的空间尺度小于全球天气和气候模型的网格尺寸，因此它们需要与数值模型中的大尺度流量统计相关，或通过参数化来表示。参数化的成功需要对潮湿对流过程有基于物理和过程层面的理解。该项目的重点是湿对流的一个重要方面，即冷池。当雨水蒸发到不饱和空气中时，它会冷却空气并增加其密度，导致空气下沉到表面并以密度流的形式水平扩散。这些密度流被称为冷池。它们可以引发新的风暴（风暴前出现阵风和凉爽空气的原因），改变近地表通量、大气稳定性，并影响对流云的特征和发展。 在该项目中，使用高分辨率数值模拟来明确解析冷池及其产生过程，并结合创新的粒子跟踪来揭示导致冷池诞生、演化和消亡的许多因素，以及量化冷池如何改变潮湿对流的特征，以及如何在全球天气和气候模型中以统计方式表示这些影响。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示，这项研究将有助于减少此类不确定性。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，并为天气和气候模型的发展做出贡献。

项目成果

Spatial and Temporal Characteristics of Asymmetries in Tropical Cyclones

热带气旋不对称性的时空特征

• DOI: 10.1029/2019gl083179
• 发表时间: 2019-07-08
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Jia;Z. Kuang
• 通讯作者: 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: 2019-01
• 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: 2019-01
• 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

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: 2019-01
• 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

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

潮湿对流大气的线性稳定性。

• DOI: 10.1175/jas-d-18-0092.1
• 发表时间: 2018-08-03
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Z. Kuang