Numerical Simulations of Derecho-producing Convective Systems

了解大范围强对流风暴（derechos）发展和维持的环境和机制仍然是一个重要的研究重点。 这些环境和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低空风切变在控制飑线强度和寿命方面的重要性。 然而，最近的研究描述观察到的derecho环境表明，低层剪切不是一个主导因素。 为了解决这些问题，已经定义了两个主要目标：1）在与derechos相关的观测环境范围内产生一组合理全面的水平非均匀数值模拟，以及2）产生一组类似的水平均匀云模型模拟。 这项研究将使用一个详细的分类所观察到的风和热力学廓线在derecho环境作为基线的数值模拟。 这一建议的智力价值是，从观测到的derecho环境和那些来自理想化的模型模拟的结果之间的差距很大程度上将被调和，我们的知识的物理机制负责的发展和维护的线导向的对流和强烈的地面风在这些类型的天气系统将增加。 更广泛的影响是对流风暴预报的改进，从而加强了公共安全和商业经济效益。

Understanding the environments and mechanisms responsible for the development and maintenance of widespread severe convective windstorms (derechos) remains an important research focus. These environments and 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 low-level wind shear in controlling the strength and longevity of squall lines. However, recent studies describing observed derecho environments have suggested that low-level shear is not a dominant factor. To address these issues, two main objectives have been defined: 1) produce a reasonably comprehensive set of horizontally non-homogeneous numerical simulations within the range of observed environments associated with derechos, and 2) produce an analogous set of horizontally homogeneous cloud-model simulations. This study will use a detailed classification of the observed wind and thermodynamics profiles in derecho environments as a baseline for the numerical simulations. The intellectual merit of this proposal is that the disparity between the results derived from observed derecho environments and those derived from idealized model simulations largely will be reconciled, and 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 will be increased. The broader impacts are the improved forecasts of convective windstorms, resulting in enhanced public safety and economic benefits to commerce.