A Reappraisal of Petterssen's Type A and Type B Cyclogenesis - A Dynamical Process Study

气旋形成是一个包罗万象的术语，指的是由与地球方向相同的向内螺旋风驱动的封闭、低压的大气循环运动的发展或加强。温带气旋沿天气锋面（斜压区）形成，并成熟为冷核气旋。这与热带气旋不同，热带气旋是由与强烈对流相关的潜热驱动的，是温暖的中央核心系统。温带气旋沿锋面边界通过可预测的序列演变的概念导致了各种分类和诊断方案的发展。Petterssen和Smebye（1950年）提出的一种方案采用了两种广泛的发展路径，A型（由低级过程指导）和B型（由上层过程指导）。它们的不同之处在于系统中负责向上垂直运动和动能发展的强迫项。尽管这种分类被广泛使用，但温带气旋动力学过程的细节仍不清楚。本项目分析了在FASTEX（1997年锋面和大西洋风暴实验）期间观测到的一些气旋形成事件，并结合其他选定的数据集，试图采用两种不同的方法来更好地诊断和解释这两种类型。这些方法分别是基于Q向量分析的传统准大气营养分析和伴随模型衍生的敏感性分析，两者都确定了与中纬度气旋发展有关的大气参数（例如剪切方向和横向垂直运动）。这些研究的广泛影响包括促进威斯康星大学学生的本科和研究生教育，开发社区资源，以及研究以温带气旋发展为主题的天气可预测性研究的新方法。2009-2010年美国冬季风暴等温带气旋的经济影响就是一个显著的例子。

Cyclogenesis is overarching term for the development or strengthening of a closed, low pressure, circular motion of the atmosphere driven by inward spiraling winds rotating in the same direction as the planet. Extratropical cyclones form along weather fronts (baroclinic zones) and mature into cold core cyclones. This is distinct from tropical cylcones which are driven by the latent heat associated with intense convection and are warm, central core systems. The notion that extratropical cyclones evolve through a predictable sequence as they pass along the frontal boundary has led to the development of a variety of classification and diagnostic schemes. One such scheme, due to Petterssen and Smebye (1950's), adopts two broad developmental paths, Type A (directed by low level processes) and Type B (directed by upper level processes). These differ as to the forcing terms responsible for upward vertical motion and development of the kinetic energy in the systems. Despite the widespread use of this classification, details of the dynamical processes in extratropical cyclones remains unclear. This project, analyzing a number of cyclogenesis events observed during FASTEX (the Fronts and Atlantic Storms Experiment, 1997) and along with other selected data sets, seeks to employ two different methodologies to better diagnose and interpret the two category types. These methodologies are respectively conventional quasigesotrophic analyses based on Q vector analysis, and an adjoint model derived sensitivity analysis, both identifying atmospheric parameters (e.g. shearwise and transverse vertical motions) that relate to mid latitude cyclone development. Broader impacts of these studies include the furtherance of undergraduate and graduate education of University of Wisconsin students, development of community resources and the investigation of new methodologies in weather predictability research on the topic of extratropical cyclone development. The economic impact of extratropical cyclones such as the 2009-2010 US winter storms were significant examples thereof.