Explaining the Nocturnal Maximum in Convection over the Great Plains Through Understanding the Interactions Between the Nocturnal Low-level Jet and Mesoscale Convective Systems

通过了解夜间低空急流与中尺度对流系统之间的相互作用来解释大平原上空对流的夜间最大值

• 批准号: 1921587
• 负责人: David Parsons
• 金额: $ 72.8万
• 依托单位: University of Oklahoma Norman Campus
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2019
• 资助国家: 美国
• 起止时间: 2019-08-15 至 2024-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1921587&HistoricalAwards=false
• 关键词: Explaining; Nocturnal; Maximum; Convection; over

Although thunderstorms can occur at any time of the day in response to weather disturbances, such as fronts and tropical cyclones, thunderstorm activity over most of the planet's land masses tends to most frequently occur in the late afternoon and early evening. The general timing of these thunderstorm is well understood as the daily heating of the earth's surface by the sun and the associated warming and moistening of the lower atmosphere provides the fuel for these storm systems. Remarkably, however, thunderstorms over the Great Plains during the summer do not follow this general tendency. Instead, the maximum in thunderstorm activity over the Great Plains takes place late in the night and into the early morning hours. This proposal seeks to understand why large thunderstorm complexes tend to occur at night over the Great Plains during the summer. The proposed effort focuses on determining whether the atmosphere over the Great Plains has relatively unique characteristics that lead to this nighttime maximum and on determining whether storm systems over this region are maintained through different processes than their late afternoon counterparts. A framework for understanding these nocturnal storms is important given that the numerical models utilized to predict weather have difficulty in representing these nocturnal storms. Accurate predictions of these events are important to society given that the nighttime thunderstorms can contain high winds, hail, and heavy rainfall. Specifically, this proposed effort seeks to explain the nocturnal maximum in organized thunderstorm activity over the Great Plains during the summer through advancing knowledge of the interaction between the spatial and temporal variations of the nocturnal low-level jet (NLLJ) and the dynamical processes maintaining nocturnal mesoscale convective systems (NMCSs). This proposal will utilize observations from the multi-agency PECAN (Plains Elevated Convection at Night) and the International H2O Project (IHOP_2002) field campaigns along with numerical simulations and theory. One aspect of this effort is to investigate the spatial and temporal variations in the thermodynamics and winds over this region within the context of the new framework for the NLLJ that shows that the jet is not simply a southerly wind maximum driven by an inertial oscillation, but a more complicated phenomenon with a westerly wind maximum above the peak southerly winds and the possibility of a slow, persistent ascent. This framework means that the NLLJ will impact convective instability through radiative processes controlling the formation of the stable nocturnal boundary layer and the heating and cooling on the sloping terrain of the region along with dynamical processes, such as local mixing, differential advection, and mesoscale ascent. A key component of the investigation will be to develop a framework that explains how the NLLJ impacts the vertical profiles of horizontal winds, Convective Available Potential Energy (CAPE), Convective Inhibition (CIN), and the Level of Free Convection (LFC). Another aspect of this effort is to focus on the role of bores and other gravity wave phenomena in initiating and maintaining convection in the NLLJ environment. Recent research has shown that bores and gravity waves are often inherent component of NMCSs over the Great Plains. The research team will investigate how the spatial and temporal variations in these vertical profiles impact the structure, movement, and evolution of NMCSs and how bores and gravity waves are generated in the NLLJ environment to impact generations of NMCSs.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.

尽管雷暴可能会在一天中的任何时间因天气障碍而发生，例如前部和热带气旋，但地球上大部分地球的土地上的雷暴活动往往最常发生在午后和傍晚。这些雷暴的一般时机被充分理解为日常通过太阳加热地球表面的加热，而下层大气的相关变暖和湿润为这些风暴系统提供了燃料。但是，值得注意的是，夏季，大平原上的雷暴并不遵循这种普遍的趋势。取而代之的是，大平原上雷暴活动的最大活动发生在深夜和清晨。该提议试图理解为什么大型雷暴络合物在夏季在大平原上倾向于发生。拟议的努力侧重于确定大平原上的气氛是否具有相对独特的特征，这些特征最大程度最大，并确定该地区的风暴系统是否通过与下午晚些时候的过程不同的过程来维护。鉴于用于预测天气的数值模型在代表这些夜间风暴方面难以实现这些夜间风暴的框架，这一点很重要。鉴于夜间雷暴可以包含大风，冰雹和大雨，对这些事件的准确预测对社会很重要。具体而言，这项拟议的努力旨在通过对夜间低级射流（NLLJ）的空间和时间变化之间的相互作用与维持夜间内镜头可信赖系统（NMCSS）的空间变化（NLLJ）的空间变化之间的相互作用来解释大平原上有组织雷暴活动的夜间最大值。该提案将利用多机构山核桃（晚上平原提升的对流）和国际H2O项目（IHOP_2002）现场活动以及数值模拟和理论的观察结果。 One aspect of this effort is to investigate the spatial and temporal variations in the thermodynamics and winds over this region within the context of the new framework for the NLLJ that shows that the jet is not simply a southerly wind maximum driven by an inertial oscillation, but a more complicated phenomenon with a westerly wind maximum above the peak southerly winds and the possibility of a slow, persistent ascent.该框架意味着NLLJ将通过控制稳定的夜间边界层形成的辐射过程以及该地区倾斜地形上的加热和冷却以及动态过程，例如局部混合，差异对流和中尺度上的表演。调查的一个关键组成部分是开发一个框架，该框架解释了NLLJ如何影响水平风，对流势能（CAPE），对流抑制（CIN）和自由对流水平（LFC）的垂直曲线。这项工作的另一个方面是将重点放在孔和其他重力波现象在NLLJ环境中启动和维持对流中的作用。最近的研究表明，孔和重力波通常是大平原上NMCS的固有组成部分。研究团队将研究这些垂直概况中的空间和时间变化如何影响NMCSS的结构，运动和演变，以及如何在NLLJ环境中产生孔和重力浪潮，以影响NMCSS的几代人。该奖项反映了NSF的法定任务，并通过评估了基金会的范围和广泛的影响，并通过评估了CRACRIA和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAIL和BRODITAILAIL和BRODITAILAILATIA和BRODITIAS。

项目成果

Bores Observed During the Warm Season of 2015–2019 Over the Southern North China Plain

• DOI: 10.1029/2022gl099205
• 发表时间: 2022-08
• 期刊: Geophysical Research Letters
• 影响因子: 5.2
• 作者: Shushi Zhang;D. Parsons;Xin Xu;Jisong Sun;Tianjie Wu;F. Xu;Na Wei;Gang Chen

Advancing Weather and Climate Forecasting for our Changing World

为不断变化的世界推进天气和气候预测

• DOI: 10.1175/bams-d-21-0262.1
• 发表时间: 2022
• 期刊: Bulletin of the American Meteorological Society
• 影响因子: 8
• 作者: Brunet, Gilbert;Parsons, David B.;Ivanov, Dimitar;Lee, Boram;Bauer, Peter;Bernier, Natacha B.;Bouchet, Veronique;Brown, Andy;Busalacchi, Antonio;Flatter, Georgina Campbell
• 通讯作者: Flatter, Georgina Campbell

Wave Disturbances and Their Role in the Maintenance, Structure, and Evolution of a Mesoscale Convection System

• DOI: 10.1175/jas-d-18-0348.1
• 发表时间: 2019-12
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Shushi Zhang;D. Parsons;Yuanzu Wang

The value of assimilating different ground-based profiling networks on the forecasts of bore-generating nocturnal convection

同化不同地基剖面网络对夜间对流生成的预测的价值

• DOI: 10.1175/mwr-d-21-0193.1
• 发表时间: 2022
• 期刊: Monthly Weather Review
• 影响因子: 3.2
• 作者: Chipilski, Hristo G.;Wang, Xuguang;Parsons, David B.;Johnson, Aaron;Degelia, Samuel K.
• 通讯作者: Degelia, Samuel K.

Emergence of a Nocturnal Low-Level Jet from a Broad Baroclinic Zone

夜间低空急流从广阔的斜压区出现

• DOI: 10.1175/jas-d-21-0187.1
• 发表时间: 2022
• 期刊: Journal of the Atmospheric Sciences
• 影响因子: 3.1
• 作者: Shapiro, Alan;Gebauer, Joshua G.;Parsons, David B.
• 通讯作者: Parsons, David B.