Investigations of Interactions Between the Atmospheric Boundary Layer and Squall Lines

该研究项目将成为多机构野外实验的组成部分，称为弓形回波和中尺度对流涡旋实验（BAMEX）。在BAMEX的现场阶段（2003年5月16日至7月6日），首席研究员将使用阿拉巴马大学亨兹维尔移动综合剖面系统（UAH-MIPS）记录大气边界层（ABL）的运动学和热力学结构以及相关的飑线结构，包括弓回波和线回波波模式（LEWP）。BAMEX项目旨在提高对弓形回波和相关恶劣天气以及中尺度对流涡旋的理解。BAMEX的具体科学目标包括：(a)记录弓形回波的生命周期，强调破坏性风的产生和龙卷风的形成机制；(b)研究在中尺度对流系统中形成的中尺度对流涡的结构和演变。这两个目标都包括观测和建模成分，最终目标是提高这些现象的可预测性。本研究的目的是促进对空间变化和时间演变的ABL与飑线、弓形回波和lewp之间相互作用的一般理解。目前关于飑线动力学对ABL特性的依赖性的知识还不是很清楚，特别是夜间边界层。在这次调查过程中，首席研究员将检查飑线的结构和演变及其相关的ABL，它将从稳定到不稳定或中性变化。因此，将获得ABL的热力学和运动学结构的详细测量。特别的重点将放在飑线的行为和夜间边界层。将讨论涉及飑线和ABL过程之间相互作用的两个重要问题：(a)将研究在飑线和弓形回波内产生强烈地面风的下沉气流的结构、动力学和热力学。(b)将研究与飑线内龙卷风发展有关的低层中尺度环流的发展。UAH-MIPS非常适合这项活动，并且将是唯一可以同时测量详细的连续风廓线（高达2-4 km AGL）和ABL内外的热力学廓线（高达10 km AGL）的固定仪器套件。这项研究可带来两个好处：(a)提高对在飑线内产生强风和龙卷风的机制的了解，这将有助于加强对这些危险现象的探测和可预测性；(b)综合分析，验证这些现象的数值模拟，从而在可预测性方面提供未来的科学进步。

This research project will be an integral component of a multi-institution field experiment termed the Bow Echo and Mesoscale Convective Vortex Experiment (BAMEX). During the field phase of BAMEX (16 May to 6 July 2003), the Principal Investigator will use the University of Alabama at Huntsville Mobile Integrated Profiling System (UAH-MIPS) to document the kinematic and thermodynamic structure of the atmospheric boundary layer (ABL) and associated squall line structure, including bow echoes and line-echo-wave patterns (LEWP). The BAMEX program seeks to improve understanding of bow echoes and associated severe weather, and mesoscale convective vortices. Specific BAMEX scientific goals include: (a) documentation of the life cycle of bow echoes, emphasizing mechanisms of damaging wind production and tornado genesis, and (b) investigation of the structure and evolution of mesoscale convective vortices that form within mesoscale convective systems. Both goals include an observational and modeling component, and the eventual goal is to improve predictability of these phenomena.The goal of this research is to advance general understanding of the interaction between the spatially variable and temporally evolving ABL and squall lines, bow echoes and LEWPs. Current knowledge of the dependence of squall line dynamics on ABL properties is not well known, particularly for the nocturnal boundary layer. During the course of this investigation, the Principal Investigator will examine the structure and evolution of squall lines and their associated ABL, which will vary from stable to unstable or neutral. Thus, detailed measurements of the thermodynamic and kinematic structure of the ABL will be acquired. A particular focus will be placed on squall line behavior and the nocturnal boundary layer. Two important problems involving interactions between squall line and ABL processes will be addressed: (a) The structure, dynamics and thermodynamics of downdrafts that produce strong surface winds within squall lines and bow echoes will be examined. (b) The development of low-level mesoscale circulations associated with development of tornadoes within squall lines will be investigated. The UAH-MIPS is ideally suited for this activity, and will be the only stationary instrument suite that can simultaneously measure detailed continuous wind profiles (up to 2-4 km AGL) and thermodynamic profiles within and above the ABL (up to 10 km AGL).Two benefits can be anticipated from this research: (a) an improved understanding of mechanisms that produce strong winds and tornadoes within squall lines, which will contribute to enhanced detection and predictability of these hazardous phenomena; and (b) comprehensive analyses that will validate numerical simulations of these phenomena, which will in turn provide future scientific advances in predictability.