Collaborative Research: Extratropical Transition of Atlantic Tropical Cyclones: An Examination of the Factors Influencing Transition and Post-Transition Intensity Change

这项研究是与威斯康星州大学的克里斯托弗·费尔登博士合作完成的。 热带气旋的外变性是一个知之甚少的过程，但由此产生的系统可以对美国东北部和加拿大的天气产生巨大影响，产生强烈的洪水降雨，风暴和海浪破坏。 当热带风暴转变为温带风暴时，其结构会从接近轴对称的气旋转变为高度不对称的气旋，其最大风速在地表附近。 这种转变通常涉及与地面锋或高层槽的相互作用，或者可能是与先前存在的热带风暴合并的结果。 主要研究人员将通过检查一些观察到的转变案例来研究转变过程，以记录生命周期和结构变化，并通过使用最先进的中尺度模型进行模型模拟。 作为这项工作的一部分，他们将测试过渡进程的各种概念模型。 他们将利用的一个主要新资源是AMSU卫星数据的可用性。 这些数据将用于推导将纳入模型模拟的热廓线和风场。 希望更好地了解过渡进程将改善预测。

This research is being done in collaboration with Dr. Christopher Velden of the University of Wisconsin. Extratropical transition of tropical cyclones is a poorly understood process, yet the resulting systems can have a tremendous impact on the weather in the northeastern U.S. and Canada, producing intense flooding rains, wind storms and wave damage. As a tropical storm transitions into an extratropical storm, its structure changes from a nearly axisymmetric cyclone with maximum winds near the surface to a highly asymmetric cyclone with strongest winds aloft. The transitions often involve interactions with surface fronts or upper level troughs or may result from mergers with pre-existing extratropical storms. The principal investigators will investigate the transition process by examining a number of observed cases of transitions to document the life cycle and structural changes and by conducting model simulations with a state-of-the-art mesoscale model. As part of this effort, they will test a variety of conceptual models of the transition process. A major new resource they will exploit is the availability of AMSU satellite data. These data will be used to derive thermal profiles and wind fields that will be incorporated into the model simulations. It is hoped that a better understanding of the transition process will improve forecasts.