An Observational and Modeling Study of Derecho-producing Convective Systems

了解负责发展和维持广泛的强对流风暴（derechos），每年造成大量人员伤亡和重大财产损失的机制，仍然是一个重要的研究重点。 这些机制已被检查与理想化的模拟强，线导向的对流（飑线），其中derecho生产对流系统是一个子集。 这些过去的研究强调了环境风切变在控制飑线强度和寿命方面的重要性。 虽然最近的研究表明，低层切变是不是一个主导因素，因为一些数值模拟表明，缺乏一个详细的观测基线描述derecho环境，阻碍了这些想法的观测比较。 为了解决这些问题，我们确定了三个主要目标：1）收集和分析derechos的大量近距离探测数据，确定风切变的分布和与这些事件相关的其他参数; 2）制作一套理想化的数值模拟，以检验线向对流对本项目观测部分确定的环境范围的敏感性; 3）在数值模拟实验中，研究维持强上升气流和强近地面风的力量。这项研究将产生一个详细的分类所观察到的风和热力学配置文件在derecho环境，并将增加我们的知识的物理机制负责发展和维护的线导向对流和强地面风在这些类型的天气系统。 研究结果可能会导致更好地预测这些破坏性的风暴。

Understanding the mechanisms responsible for the development and maintenance of widespread severe convective windstorms (derechos), that are responsible for numerous casualties and significant property damage each year, remains an important research focus. These mechanisms have been examined with idealized simulations of strong, line-oriented convection (squall lines) of which derecho-producing convective systems are a subset. These past studies emphasize the importance of environmental wind shear in controlling the strength and longevity of squall lines. While recent studies describing observed derecho environments suggest that low-level shear is not as dominant a factor as some numerical simulations have suggested, the lack of a detailed observational baseline describing derecho environments has hindered the comparison of these ideas to observations. To address these issues three main objectives have been defined: 1) collect and analyze a large set of proximity soundings from derechos and determine the distribution of wind shear and other parameters associated with these events; 2) produce a set of idealized numerical simulations to examine the sensitivity of line-oriented convection to the range of environments identified in the observational portion of this project; 3) examine the forces responsible for maintaining the strong updrafts and the strong near-surface winds within the numerical modeling experiments. This study will produce a detailed classification of the observed wind and thermodynamics profiles in derecho environments and will increase our knowledge of the physical mechanisms responsible for the development and maintenance of the line-oriented convection and the strong surface winds within these types of weather systems. Results potentially will lead to better forecasts of these destructive wind storms.