Numerical Studies of Tropical Cyclogenesis and Hurricane Andrew (1992)

热带气旋和安德鲁飓风的数值研究 (1992)

• 批准号: 9802391
• 负责人: Da-Lin Zhang
• 金额: $ 35.64万
• 依托单位: University of Maryland, College Park
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1999
• 资助国家: 美国
• 起止时间: 1999-01-01 至 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9802391&HistoricalAwards=false
• 关键词: Numerical; Studies; Tropical; Cyclogenesis; Hurricane

Adequate understanding of the genesis and inner core structure of tropical cyclones is a high priority research area under the U.S. Weather Research Program. Although there have been numerous studies of tropical cyclogenesis in the past decades, little work has been done to investigate cyclogenesis from mesoscale convective systems (MCSs) and the inner-core structures of hurricanes. Thus, the objectives of this research are to a) test the hypothesis that convectively generated mid-level mesovortices could induce tropical cyclogenesis under optimum environmental conditions; and b) simulate and investigate the inner-core structures and evolution of Hurricane Andrew (1992). To gain insight into the nature of tropical cyclogenesis, emphasis will be placed on a) the processes leading to the generation and amplification of lower-level cyclonic vorticity in tropical storms in relation to mid-level mesovortices, and b) the mechanisms responsible for the transformation from MCSs with a low-level cold pool into intense mesocyclones that are characterized by deep warm-cored structures. Finally, model-based diagnosis will be performed to examine the roles of air-sea interaction, cloud-radiation interaction and meso-larger scale interaction in the transformation from MCSs to tropical storms.For the second objective, numerical studies of hurricane intensity will be performed. Specifically, 1) aircraft observations during the rapid intensification of Andrew and SSM/I data will be used to help understand the predictability of the inner-core structures by nudging the model integration towards the observations during a pre-forecast period; 2) higher resolution (i.e. 2 - 3 km) explicit simulations will be conducted to demonstrate the capability of reproducing inner-core structure and intensity and, thereby, gain insight into the double eyewall cycle that is associated with the rapid decay followed by explosive deepening of the storm; 3) an advanced oceanic and atmospheric mesoscale model will be coupled in order to study the impact of local sea-surface temperature changes on the development of inner-core structures; and 4) various sensitivity simulations will be performed to examine the effects of different cumulus parameterization schemes, shallow convection, cloud microphysical processes (water vs. ice), cloud-radiation interaction and air-sea interaction on the simulation of the storm.Successful completion of the proposed tasks will provide a better understanding of the dynamic effects of MCSs on larger-scale flows, the processes leading to tropical cyclogenesis from MCSs, the inner-core structures of hurricanes and various processes during rapid deepening. Satisfying results may open a new important era for tropical cyclogenesis research and for improving the numerical prediction of hurricanes and their structure at landfall.

充分了解热带气旋的成因和内核结构是美国天气研究计划的一个高度优先的研究领域。在过去的几十年里，人们对热带气旋的形成进行了大量的研究，但对中尺度对流系统（MCSs）和飓风内核结构的气旋形成进行研究的工作却很少。因此，本研究的目的是：a)验证在最佳环境条件下对流产生的中层中涡旋可以诱发热带气旋形成的假设；b)模拟和研究飓风安德鲁（1992）的内核结构和演变。为了深入了解热带气旋形成的本质，重点将放在a)与中层中涡旋有关的导致热带风暴中低层气旋涡度产生和放大的过程，以及b)从具有低层冷池的mcs转变为具有深部暖核结构特征的强烈中气旋的机制。最后，基于模式的诊断将检验海气相互作用、云辐射相互作用和中尺度相互作用在MCSs向热带风暴转变中的作用。对于第二个目标，将进行飓风强度的数值研究。具体而言，1)在Andrew快速增强期间的飞机观测数据和SSM/I数据将通过推动模式整合向预预报期间的观测数据来帮助理解内核结构的可预测性；2)将进行更高分辨率（即2 - 3公里）的明确模拟，以证明再现内核结构和强度的能力，从而深入了解与风暴急剧加深后的快速衰减相关的双眼壁循环；3)采用先进的海洋和大气中尺度模式耦合，研究局地海温变化对内核结构发展的影响；4)将进行各种灵敏度模拟，以检验不同的积云参数化方案、浅对流、云微物理过程（水与冰）、云辐射相互作用和海气相互作用对风暴模拟的影响。成功完成所提出的任务将有助于更好地了解MCSs对大尺度气流的动态影响、导致MCSs形成热带气旋的过程、飓风的内核结构以及快速加深过程中的各种过程。令人满意的结果可能为热带气旋形成研究和改进飓风及其登陆结构的数值预报开辟一个新的重要时代。