The Formation and Climatological Distribution of Tornadoes within Quasi-Linear Convective Systems

美国每年大约有1000次龙卷风。 这些龙卷风是由各种各样的风暴类型产生的，包括超级单体雷暴和准线性对流系统（QLCS），如飑线和弓形回波。QLCS中可行的龙卷风繁殖地点的水平范围比单个超级单体大一个数量级。 QLCS龙卷风可能很强大，并产生广泛的破坏。 此外，从多普勒雷达的角度来看，QLCS龙卷风发生的平均速度似乎比超级单体龙卷风发生的速度更快。 QLCS龙卷风的地理分布、季节分布和日分布尚不清楚，大量研究致力于对超级单体龙卷风的研究，但尚未有专门针对QLCS龙卷风的研究。 由于缺乏相关的QLCS龙卷风发生/龙卷风气候学的基本知识，可以说，业务气象学家通常无法评估QLCS龙卷风的潜在风险，因此，适当地提醒公众注意这种危险。 主要研究者将进行一项补充性两部分研究。 目标是：1.估计QLCS产生的龙卷风的气候分布;描述它们发生的环境条件;确定龙卷风与非龙卷风QLCS的基于雷达的属性。了解龙卷风与非龙卷风的QLCS形态和演变。这项研究的成功完成将增加QLCS龙卷风的基础知识，并将在恶劣天气预报和预警业务中应用。

Approximately 1000 tornadoes are observed within the U.S. annually. These tornadoes are spawned from a variety of parent storm types, including supercell thunderstorms and quasi-linear convective systems (QLCSs) such as squall lines and bow echoes.The horizontal extent of viable tornado-breeding sites is an order of magnitude larger in QLCSs than in individual supercells. QLCS tornadoes can be strong and produce extensive damage. Also, QLCS tornadogenesis appears to occur, on average, more rapidly than does supercell tornadogenesis from the perspective of Doppler radar. The geographical, seasonal, and diurnal distributions of QLCS tornadoes are unknown.A significant amount of research effort has been devoted to the study of supercell tornadogenesis, but no published research addresses specifically QLCS tornadogenesis. Owing to the related lack of fundamental knowledge of QLCS tornadogenesis/tornado climatology, it may be argued that operational meteorologists are generally unable to assess the potential risk of tornadic winds in QLCSs and, hence, properly alert the public to this danger. The Principal Investigator will undertake a complementary two-part study. The objectives are to: 1. Estimate the climatological distributions of QLCS-spawned tornadoes; characterize the environmental conditions under which they occur; determine radar-based attributes of tornadic versus non-tornadic QLCS.2. Gain an understanding of tornadic versus non-tornadic QLCS morphology and evolution.Successful completion of this research will increase fundamental knowledge of QLCS tornadoes and will have applications in severe weather forecasting and warning operations.