On the Marsupial Theory for Tropical Cyclogenesis Within Tropical Wave and Monsoon Trough Environments: A Multiscale Observational, Modeling and Theoretical Study

关于热带波和季风槽环境中热带气旋发生的有袋动物理论：多尺度观测、建模和理论研究

• 批准号: 0733380
• 负责人: Michael Montgomery
• 金额: $ 20万
• 依托单位: Naval Postgraduate School
• 依托单位国家: 美国
• 项目类别: Interagency Agreement
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-02-15 至 2014-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0733380&HistoricalAwards=false
• 关键词: Marsupial; Theory; Tropical; Cyclogenesis; Within

When, where, and how weakly rotating convective regions develop into full-blown tropical cyclones remains an essentially unsolved problem in atmospheric dynamics, albeit a problem with unusually significant implications for forecasting high-impact weather. In this project Montomgery and his group will explore his "marsupial hypothesis," which relates tropical cyclogenesis to the critical layers of tropical waves. The "marsupial hypothesis" comprises three sub-hypotheses:1) The weakly rotating regions of thunderstorms that develop into tropical cyclones form at the critical level, or steering level, of tropical traveling waves. At this level the wave speed equals that of the background wind, so that fluid, including the the weakly rotating "proto-vortex," moves with the wave.2) For stronger waves, the critical level evolves into a critical layer, which forms a pocket of closed streamlines. In this pocket, the developing vortex is partially isolated or protected (thus "marsupial" theory) from the entrainment of dry air and the deleterious affects of vertical shear.3) Tropical waves are amplified by the latent heat release associated with these proto-vortices.These hypotheses will be tested in a program of observational analyses and modeling. Preliminary analyses of atmospheric data indicates that critical layers of African easterly waves are, as hypothesized, preferred regions for tropical cyclone development, and that convection within the wave trough helps to maintain the wave. These analyses will be extended to monsoon trough cases, and cyclogenesis cases will be balanced with null cases, in which cyclogenesis does not occur. Problems with reanalyses in the tropics - that the results are strongly conditioned by the cumulus parameterization scheme - will be circumvented by analyzing data from other sources, including the Tropical Rainfall Measurement Mission (TRMM) satellite data, and in-situ data obtained during the summer-fall 2008 T-PARC (THe Observing System Research and Predictability Experiment (THORPEX) Pacific Asian Regional Campaign) field campaigns.Model experiments will be carried out using the Weather Research and Forecasting (WRF) model. Dry experiments will examine the vortex shedding from tropical waves that produces proto-vortices. Moist experiments with standard treatments of cumulus convection will examine wave-amplification, and cloud-scale modeling will consider the growth of proto-vortices.Broader impacts of this project derive from the societal benefits of improved understanding of tropical cyclogenesis and the potential impact of such understanding on prediction. Montgomery's group will collaborate with NOAA's Hurricane Research Division in their annual field program of research. Graduate students from the military services will be trained.

弱旋转对流区何时、何地以及如何发展成全面的热带气旋仍然是大气动力学中一个基本上未解决的问题，尽管这个问题对预测高影响天气具有异常重要的意义。在这个项目中，蒙托吉里和他的团队将探索他的“有袋动物假说”，该假说将热带气旋生成与热带海浪的临界层联系起来。“有袋动物假说”包括三个子假说：1）发展成热带气旋的雷暴的弱旋转区域形成于热带行波的临界水平或转向水平。在这个水平上，波的速度等于背景风的速度，因此流体，包括弱旋转的“原涡”，随波移动。2）对于更强的波，临界水平演变成临界层，形成封闭流线的口袋。在这个口袋里，发展中的涡旋被部分隔离或保护（因此是“有袋动物”理论），免受干空气的夹带和垂直剪切的有害影响。3）热带波被与这些原涡旋相关的潜热释放放大。这些假设将在观测分析和建模程序中进行测试。大气数据的初步分析表明，非洲东风波的关键层，假设，热带气旋发展的首选区域，以及波槽内的对流有助于维持波。这些分析将扩展到季风槽的情况下，和气旋的情况下，将与空的情况下，其中气旋不发生平衡。 热带地区再分析的问题--结果受到积云参数化方案的强烈影响--将通过分析其他来源的数据来规避，包括热带降雨测量使命（TRMM）卫星数据，和2008年夏季-秋季T-PARC期间获得的现场数据（观测系统研究及预报试验太平洋亚洲区域活动）实地活动。模式试验将利用天气研究及预报（WRF）模型。干实验将检查产生原涡旋的热带波的涡旋脱落。湿实验与积云对流的标准处理将检查波放大，云尺度模拟将考虑原vortices. The更广泛的影响，这个项目的社会效益，提高对热带气旋生成的理解和这种理解的预测的潜在影响。蒙哥马利的小组将与美国国家海洋和大气管理局的飓风研究部门合作进行年度实地研究计划。将培训来自军队的研究生。