Investigations of Interactions Between the Atmospheric Boundary Layer and Squall Lines

这项研究项目将是多机构现场实验的一个组成部分，该实验名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)，首席调查员将使用阿拉巴马大学亨茨维尔移动综合廓线系统(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锋线结构，包括弓形回波和线回波模式(LEWP)。BAMEX计划旨在提高对弓形回波和相关的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，强调破坏性风产生和龙卷风形成的机制，以及(B)调查在中尺度对流系统内形成的中尺度对流涡旋的结构和演变。这两个目标都包括观测和模拟部分，最终目标是提高对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高层大气环流和咆哮线、弓形回波和低层大气环流之间的相互作用的一般理解。目前，我们还不清楚系统边界层边界层特性对广场线动力学特性的影响。在这次调查过程中，首席调查员将研究由稳定到不稳定或中性的锋线及其相关的边界线的结构和演变。因此，将获得ABL的热力学和运动学结构的详细测量。一个特别的焦点将放在斜线行为和夜间边界层上。本课程将讨论两个重要的问题，包括：(A)研究在斜线和弓形回波中产生强地面风的下沉气流的结构、动力学和热力学。(B)将调查与飓风线内龙卷风发展有关的低层中尺度环流的发展情况。UAH-MIPS非常适合这项活动，也将是唯一一套固定的仪器，可以同时测量详细的连续风廓线(可达2-4千米AGL)和ABL及其以上的热力学廓线(可达10千米AGL)。这项研究可以预期有两个好处：(A)提高对狂风线内产生大风和龙卷风的机制的了解，这将有助于提高对这些危险现象的探测和预测能力；(B)将验证对这些现象的数值模拟的综合分析，这将反过来提供未来在可预测性方面的科学进展。

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.