Collaborative Research: Measurement and Analysis of Nocturnal Mesoscale Convective Systems and Their Stable Boundary Layer Environment During PECAN

平原夜间高架对流（PECAN）实验将研究夜间中尺度对流系统（MCSs）和对流的演变及其与夜间稳定边界层（SBL）环境演变的相互作用。本研究旨在实现PECAN的两个主要目标：1)表征夜间MCS结构从地面向高空的转变，以及MCS产生的冷池与夜间SBL的相互作用；2)确定夜间低层急流（NLLJ）上方稳定边界层和垂直风廓线对地面MCS和高空MCS的组织和演变的影响。为了纠正目前缺乏对夜间mcs及其SBL环境的详细、综合观测，该项目将在PECAN期间使用移动地面雷达、移动探测系统和移动介网与其他地面和机载观测平台一起观测夜间mcs和对流。多雷达合成、数据同化和建模将提供这些组合观测的综合分析，以评估夜间MCS的详细内部结构以及静态稳定性、预先存在的边界和风切变对夜间MCS演变过程的影响。智力优势：该项目强调夜间MCSs及其SBL环境的紧密协调观测，使用多个移动多普勒和双极化雷达阵列，结合移动测深和地面原位观测系统。这些观测结果将被整合，以获得三维气流合成、降水场、MCSs热结构和新启动的对流及其环境。移动雷达是必不可少的，因为它们可以在PECAN域内的任何区域提供增强的时空分辨率和低水平观测。需要c波段雷达，因为它既能穿透强降水，又能感知晴空流入。移动C波段和x波段双偏振雷达将提供超出WSR-88D偏振雷达典型工作范围和低于基本扫描高度的微物理信息。通过提供降水内外独特的浮力和切变剖面，移动探测和地面观测补充了雷达风测量，从而解决了MCS内部动力学问题，并表征了与MCS相互作用的SBL环境。这些数据与其他来自固定和移动地面雷达、剖面仪、中网和飞机的PECAN数据相结合，对于根据现场环境条件解释夜间MCS演变，以及为MCS的云动态微物理模型模拟提供输入和验证至关重要。该项目的科学目标是：(i)记录夜间MCSs和对流的内部结构和演变；（ii）建立控制夜间MCS演化的环境因素和相关物理机制；（iii）在详细的云分辨模型中检验关于MCS动态微物理强迫和MCS-环境相互作用的假设。这里进行的研究将推进MCS内部动力学和与SBL相互作用的基础知识，并将在云分辨模型中更好地表示这两者。更广泛的影响：表征夜间MCSs的形态以及冷池对流区前方和附近的温度、湿度和风的垂直剖面，对于帮助提高诊断的特异性和准确性，以及对恶劣天气、强降雨、山洪暴发和飞机结冰状况的地理范围和持续时间的短期预测至关重要。此外，这些PECAN现场观测对于改进数据同化系统和改进夜间MCSs及其SBL环境的未来操作数值预测至关重要。这里收集的数据集也将用于大学课程到研究生水平。几名本科生和研究生将通过整合到数据收集和现场后期阶段分析中，接受执行大型大气现场活动的培训。最后，这里收集的数据将提供给其他国家科学基金会和国家海洋和大气管理局的调查人员，作为PECAN项目的一部分。

The Plains Elevated Convection At Night (PECAN) experiment will investigate the evolution of nocturnal mesoscale convective systems (MCSs) and convection and their interactions with the evolving nocturnal stable boundary layer (SBL) environment. This proposal addresses two primary goals of PECAN: 1) To characterize the transition from surface-based to elevated nocturnal MCS structure and the interaction of cold pools generated by MCSs with the nocturnal SBL, and 2) to determine how the organization and evolution of surface-based and elevated MCSs are influenced by the stable boundary layer and the vertical profile of wind and stability above the nocturnal low-level jet (NLLJ). To rectify the present paucity of detailed, integrated observations of nocturnal MCSs and their SBL environments, the project will observe nocturnal MCSs and convection with mobile ground-based radars, mobile sounding systems, and mobile mesonets in concert with other ground-based and airborne observing platforms during PECAN. Multi-radar syntheses, data assimilation, and modeling will provide the integrated analyses of these combined observations to evaluate the detailed internal structure of nocturnal MCSs and the impact of static stability, pre-existing boundaries, and wind shear on nocturnal MCS evolution processes.Intellectual Merit:This project emphasizes the tightly coordinated observation of nocturnal MCSs and their SBL environments with an array of multiple mobile Doppler and dual-polarimetric radars in conjunction with mobile soundings and surface in situ observing systems. These observations will be integrated to obtain 3-D airflow syntheses, precipitation fields, and thermal structure of MCSs and newly initiated convection and their environments. Mobile radars are essential as they can provide enhanced temporal and spatial resolution and low-level observations over any area within the PECAN domain. C-band radars, with their ability to both penetrate heavy precipitation and sense clear-air inflow, are required. The mobile C- and X-band dual-polarimetric radars will provide microphysical information beyond the typical operating ranges and below base-scan altitudes of the polarimetric WSR-88D radars. The mobile sounding and surface observations complement the radar wind measurements by providing unique buoyancy and shear profiles both within and outside of precipitation, thus resolving internal MCS dynamics and characterizing the SBL environment that interacts with the MCSs. These data, in combination with other PECAN data from fixed and mobile ground-based radar, profilers, mesonets, and aircraft, are essential for interpreting nocturnal MCS evolution with respect to in situ environmental conditions and for providing input and validation of cloud dynamical-microphysical model simulations of MCSs. The scientific objectives of this project are to: (i) document the internal structure and evolution of nocturnal MCSs and convection; (ii) establish the environmental ingredients and related physical mechanisms that control nocturnal MCS evolution; and (iii) test hypotheses concerning MCS dynamical microphysical forcing and MCS-environment interactions within detailed cloud-resolving models. The research conducted here will advance fundamental knowledge of the internal MCS dynamics and interactions with the SBL and will enable better representations of both within cloud-resolving models.Broader Impacts:Characterizing the morphology of nocturnal MCSs and the vertical profiles of temperature, humidity and winds ahead of and near the convective region in the cold pool are essential to helping improve the specificity and accuracy of diagnoses and short-term predictions of the geographical extent and duration of severe weather, heavy rainfall, flash flooding, and aircraft icing conditions. Additionally, these PECAN field observations will be essential for refining data assimilation systems and improving future operational numerical predictions of nocturnal MCSs and their SBL environments. The datasets collected here will also be used in university classes through graduate level. Several undergraduate and graduate students will be trained in the execution of a large atmospheric field campaign by being integrated into the data collection and post-field phase analysis. Lastly, the data collected here will be made available to other NSF and NOAA investigators identified as part of the PECAN project.