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

气旋发生是最主要的术语，指由向内旋转的风驱动的、与地球方向相同的大气闭合、低压、圆周运动的发展或加强。温带气旋沿着天气锋面(斜压区)形成，并成熟为冷核气旋。这与热带圆锥体不同，热带圆锥体是由与强烈对流相关的潜热驱动的，是温暖的中心核心系统。温带气旋在通过锋面边界时会以可预测的顺序演变，这一概念导致了各种分类和诊断方案的发展。一个这样的方案，由于Petterssen和Smebai(1950‘S)，采用了两条广泛的发展道路，类型A(由低水平过程指导)和类型B(由较高水平过程指导)。对于系统中负责向上垂直运动和动能发展的强迫项，这两个项是不同的。尽管这种分类被广泛使用，但温带气旋动力过程的细节仍然不清楚。该项目分析了在FASTEX(锋面和大西洋风暴实验，1997年)期间观察到的若干气旋发生事件，以及其他选定的数据集，力求采用两种不同的方法来更好地诊断和解释这两种类型。这两种方法分别是基于Q矢量分析的传统准营养分析和伴随模式的敏感性分析，两者都确定了与中纬度气旋发展有关的大气参数(例如切变和横向垂直运动)。这些研究的更广泛影响包括促进威斯康星大学学生的本科生和研究生教育，开发社区资源，以及调查关于温带气旋发展主题的天气预报性研究的新方法。2009-2010年美国冬季风暴等温带气旋的经济影响就是重要的例子。

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.