Collaborative Research: Impacts of Microphysical, Thermodynamic, and Dynamical Processes on Nocturnal and Oceanic Convective Systems via Analyses from PECAN and HAIC/HIWC

合作研究：通过 PECAN 和 HAIC/HIWC 的分析，微物理、热力学和动力过程对夜间和海洋对流系统的影响

• 批准号: 1841966
• 负责人: Robert Rauber
• 金额: $ 34.97万
• 依托单位: University of Illinois at Urbana-Champaign
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-05-15 至 2023-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1841966&HistoricalAwards=false
• 关键词: Collaborative; Research; Impacts; Microphysical; Thermodynamic

Mesoscale convective systems (MCSs) are responsible for a large portion of summertime precipitation in the Great Plains and Midwest of the United States and produce a large range of hazards, including strong winds, hail, flash flooding and occasional tornadoes. Thus, accurate understanding and forecasting of these systems is important for public safety. Processes responsible for the growth and evolution of a particular class of MCSs, occurring at night, are especially poorly understood. This project examines mechanisms responsible for the evolution of such nocturnal storms using a unique set of data obtained by an instrumented aircraft flying in clouds generated by and trailing behind nocturnal thunderstorms during the 2015 Plains Elevated Convection at Night (PECAN) field experiment. In particular, the project is assessing how small-scale processes occurring in clouds generate cold air which in turn generates features that act to force new air masses to rise, leading to the development of new thunderstorms that subsequently generate more trailing clouds and rain. The second component of the project examines the properties of clouds generated by thunderstorms occurring in the Tropics. This component was motivated by a problem faced by aviation, namely that aircraft flying at commercial flight altitudes can encounter conditions where there is no noticeable echo on their radar yet encounter large amounts of small ice crystals not detected by the radar; such conditions can be problematic for aircraft engines as evidenced by several engine events over the last 30 years. This project uses data collected by research aircraft flying in such conditions. The research aircraft were instrumented with probes measuring cloud properties during the 2015 and 2016 High Ice Water Content (HIWC) projects conducted off the coast of Darwin, Australia and French Guiana. The project is examining processes that lead to the development of large numbers of small ice crystals by identifying the environmental conditions under which these small crystals form and grow. In both projects, model simulations are also being used to evaluate the role of specific processes in driving and maintaining thunderstorms (PECAN) and for generating small ice crystals (HIWC). Further, both projects acquired next generation polarimetric radar data coincident with the aircraft cloud observations so that cloud properties retrieved from polarimetric radar data can be validated, meaning that data from polarimetric radar in the future can ultimately be used to extend the limited range duration of the field experiment measurements. At a more technical level, the PECAN data are being used to evaluate the hypothesis that microphysical cooling processes in developing and mature stratiform regions of MCSs force downdraft circulations that create mesoscale gravity wave features on the stable nocturnal boundary layer (SNBL) that in turn focus, organize and maintain future convective activity. In context of storm kinematics and dynamics as derived from multiple Doppler radar analyses and modeling investigations, the PECAN data are being used to (1) characterize the microphysical and thermodynamic structure of the transition zone, notch and rear anvil regions in formative, mature and dissipative stages of the PECAN elevated nocturnal MCSs; (2) quantify and understand how the horizontal and vertical distribution of latent cooling evolves across MCSs during their lifecycles and contributes to downdrafts and gravity wave features; and (3), determine how gravity wave features on the SNBL give rise to lifting that then drives convection and maintains the organization and long lifetime of nocturnal MCSs. The HIWC data are being used to (1) characterize the microphysical and thermodynamic properties of high IWC regions and contrasting them against properties derived from observations obtained in regions without high IWCs; (2) determine polarimetric radar signatures of high IWC regions and investigate how these signatures differ depending upon the relative prevalence of small ice crystals; (3) develop representations of size distributions and mass-dimensional relationships for high IWC regions as a volume or surface of equally realizable solutions in the appropriate coefficient phase space; and (4) conduct simulations to identify processes responsible for the numerous small ice crystals found above oceanic convective cores, and compare against HIWC observations. The broad impacts are (1) improved understanding so that operational forecasters and nowcasters can better anticipate the evolution of convective phenomena; (2) enhanced education and training opportunities (several graduate students are earning advanced degrees); (3) incorporation of PECAN and HAIC/HIWC data into courses taught and textbooks published by the PIs; (4) advanced scientific understanding of high IWC conditions that have led to about 150 power loss and/or pitot tube failures in commercial aircraft over the last several years.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.

中尺度对流系统（MCS）是美国大平原和中西部夏季降水的主要来源，并产生大范围的灾害，包括强风、冰雹、山洪和偶尔的龙卷风。因此，准确理解和预测这些系统对于公共安全非常重要。人们对夜间发生的特定类型 MCS 的生长和进化过程知之甚少。该项目利用 2015 年平原夜间高对流 (PECAN) 现场实验期间，在夜间雷暴产生并尾随其后的云层中飞行的仪表飞机获得的一组独特数据，研究了此类夜间风暴演变的机制。特别是，该项目正在评估云中发生的小规模过程如何产生冷空气，冷空气反过来又产生迫使新气团上升的特征，导致新雷暴的发展，从而产生更多的尾随云和降雨。该项目的第二部分研究热带地区雷暴产生的云的特性。该组件的动机是航空面临的一个问题，即在商业飞行高度飞行的飞机可能会遇到雷达上没有明显回波但遇到雷达未检测到的大量小冰晶的情况；过去 30 年发生的几起发动机事件就证明了这种情况可能会给飞机发动机带来问题。该项目使用在这种条件下飞行的研究飞机收集的数据。 2015 年和 2016 年在澳大利亚达尔文和法属圭亚那海岸进行的高冰水含量 (HIWC) 项目期间，研究飞机配备了测量云特性的探测器。该项目正在通过确定这些小冰晶形成和生长的环境条件来研究导致大量小冰晶形成的过程。在这两个项目中，模型模拟还用于评估特定过程在驱动和维持雷暴 (PECAN) 以及生成小冰晶 (HIWC) 中的作用。此外，这两个项目都获取了与飞机云观测一致的下一代偏振雷达数据，以便可以验证从偏振雷达数据中检索到的云特性，这意味着未来来自偏振雷达的数据最终可以用于延长飞机的有限范围持续时间。现场实验测量。在更技术的层面上，PECAN 数据被用来评估这样的假设：MCS 发展中和成熟的层状区域中的微物理冷却过程迫使下沉气流环流在稳定的夜间边界层 (SNBL) 上产生中尺度重力波特征，进而聚焦，组织和维持未来的对流活动。在源自多个多普勒雷达分析和建模研究的风暴运动学和动力学背景下，PECAN 数据被用于 (1) 表征形成、成熟和耗散的过渡区、凹口和后砧区域的微物理和热力学结构。 PECAN 夜间 MCS 升高的阶段； (2) 量化并了解潜在冷却的水平和垂直分布如何在 MCS 的生命周期中演变，以及如何影响下沉气流和重力波特征； (3) 确定 SNBL 上的重力波特征如何引起升力，然后驱动对流并维持夜间 MCS 的组织和长寿命。 HIWC 数据用于 (1) 表征高 IWC 区域的微物理和热力学特性，并将其与从没有高 IWC 的区域获得的观测结果得出的特性进行对比； (2) 确定高 IWC 区域的极化雷达特征，并研究这些特征如何根据小冰晶的相对普遍程度而有所不同； (3) 将高 IWC 区域的尺寸分布和质量维度关系表示为适当系数相空间中同等可实现解的体积或表面； (4) 进行模拟，以确定在海洋对流核心上方发现的大量小冰晶的形成过程，并与 HIWC 观测结果进行比较。广泛的影响是（1）提高了认识，以便业务预报员和临近预报员能够更好地预测对流现象的演变； (2) 增加教育和培训机会（几名研究生正在获得高级学位）； (3) 将PECAN和HAIC/HIWC数据纳入PI教授的课程和出版的教科书中； (4) 对过去几年中导致商用飞机约 150 起功率损失和/或皮托管故障的高 IWC 条件的先进科学理解。该奖项反映了 NSF 的法定使命，并通过使用基金会的智力价值和更广泛的影响审查标准。

项目成果

Spatiotemporal Evolution of the Microphysical and Thermodynamic Characteristics of the 20 June 2015 PECAN MCS

2015 年 6 月 20 日 PECAN MCS 微物理和热力学特征的时空演化

• DOI: 10.1175/mwr-d-19-0293.1
• 发表时间: 2020-04
• 期刊: Monthly Weather Review
• 影响因子: 3.2
• 作者: Stechman, Daniel M.;McFarquhar, Greg M.;Rauber, Robert M.;Bell, Michael M.;Jewett, Brian F.;Martinez, Jonathan
• 通讯作者: Martinez, Jonathan

Composite In Situ Microphysical Analysis of All Spiral Vertical Profiles Executed within BAMEX and PECAN Mesoscale Convective Systems

在 BAMEX 和 PECAN 中尺度对流系统中执行的所有螺旋垂直剖面的复合原位微物理分析

• DOI: doi: 10.1175/jas-d-19-0317.1
• 发表时间: 2020-07
• 期刊: Journal of the atmospheric sciences
• 影响因子: 3.1
• 作者: Stechman, D.M.;McFarquhar, G.M.;Rauber, R.M.;Jewett, B.F.;and Black, R.A.
• 通讯作者: and Black, R.A.