Collaborative Research: Observational and Modeling Study of Hurricane Rainbands and Intensity Changes

主要研究人员将对飓风强度变化进行协调的建模和观测研究，这些变化与内核涡旋动力学、外雨带区域二次风极大值的形成、眼壁替换周期以及外雨带的动力学/热力学反馈有关。 本研究的主要目的有二：1）同时探讨飓风雨带外围及内核区的动力及热力结构。2)研究雨带和主飓风涡旋环流的相互作用以及这些相互作用在飓风强度变化中的作用。雨带是飓风内核外不对称加热的主要来源。 这种不对称的加热导致局部位涡（PV）的功能，这反过来又可能是“轴对称”的径向切向风切变。 眼壁动力学然后被重组和整体风暴强度的变化。 因此，雨带结构的详细演变与风暴的演变是密不可分的。 雨带的内部结构将通过将雨带细分为对流和层状区域来研究，其中加热的垂直分布以及PV生成模式是不同的。 通过同时观测雨带和眼壁结构，雨带的位涡特征可以与风暴强度变化相联系。 在雨带的对流区和层状区产生的位涡特征将被用来研究雨带中次风极大值的形成。 随着次级风极大值的形成，它们将被检查如何增强和轴对称化，并最终成为主眼墙。为实现目标1），主要调查员将使用配备多普勒雷达和下投式探空仪的飞机。 首先，将分析1998-2003年飓风季节NOAA P3收集的数据。 Fabian（2003）和伊莎贝尔（2003）将被优先考虑，它们展示了清晰的眼墙、雨带和眼墙更换周期。 虽然在这些风暴中收集了机载多普勒雷达数据，但飞行轨迹并不专门用于拟议研究的目标。 因此，对这些风暴的分析将作为设计多飞机飞行计划的基础，以满足本研究的特定目标。 该飞行计划将被称为雨带和强度变化实验（RAINEX），将涉及两架配备多普勒的NOAA WP-3D飞机以及配备国家大气研究中心ELDORA多普勒系统的NRL P3。 RAINEX将在美国国家海洋和大气管理局（NOAA）2005年大西洋飓风现场计划的范围内运行，并将与NOAA科学家协调。为了实现目标2），主要研究人员将使用迈阿密大学的涡旋跟踪，多嵌套，非静力中尺度模式（MM 5）与一个波浪模式和一个海洋模式耦合，进行了3-7天的积分，显示了飓风内核和雨带在1- 2公里网格分辨率。 将寻求模型模拟与机载雷达和下投式探空仪数据的一致性。 将对2005年实地方案调查的案例进行近实时模拟。这项研究将有助于提高飓风和相关的极端风和山洪事件的预测，对美国的生命和财产造成破坏性影响的社会目标。S.沿海地区。

The Principal Investigators will perform a coordinated modeling and observational study of hurricane intensity changes in relation to inner-core vortex dynamics, formation of secondary wind maxima in the outer rainband region, eyewall replacement cycles, and dynamic/thermodynamic feedbacks of outer rainbands. The two main objectives of this study are: 1) To examine structures (both dynamic and thermodynamic) of hurricane outer rainband and inner core regions simultaneously. 2) To investigate the interactions of the rainbands and primary hurricane vortex circulation and the role of these interactions in hurricane intensity changes. Rainbands are major sources of asymmetric heating outside of the hurricane inner core. This asymmetric heating leads to localized potential vorticity (PV) features, which may in turn be "axisymmetrized" by the radial shear of the tangential wind. The eyewall dynamics are then restructured and the overall storm intensity changes. Thus, the detailed evolution of the structure of the rainbands is integrally involved in storm evolution. The internal structure of the rainbands will be examined by subdividing the bands into convective and stratiform regions where the vertical distributions of heating and thus PV generation patterns are different. By simultaneously examining the eyewall and rainband structures, the PV features of the rainbands can be related to storm intensity changes. The PV features generated in the convective and stratiform regions of rainbands will be examined in relation to the formation of secondary wind maxima in the rainbands. As the secondary wind maxima take shape, they will be examined for how they may intensify and axisymmetrize and eventually take over as the main eyewall. To address objective 1), the Principal Investigators will use aircraft equipped with Doppler radar and dropsondes. First, data collected by the NOAA P3s during the 1998-2003 hurricane seasons will be analyzed. Priority will be given to Fabian (2003) and Isabel (2003), which exhibited well-defined eyewalls, rainbands, and eyewall replacement cycles. Although airborne Doppler radar data were collected in these storms, the flight tracks were not dedicated to the objectives of the proposed study. The analysis of these storms will, therefore, serve as the foundation for the design of a multi-aircraft flight program dedicated to meet the specific objectives of this research. This flight program will be called the Rainband and Intensity Change Experiment (RAINEX), and will involve the two Doppler equipped NOAA WP-3D aircraft plus the NRL P3 with the National Center for Atmospheric Research ELDORA Doppler system. RAINEX will operate within the context of the National Oceanic and Atmospheric Administration (NOAA) 2005 hurricane field program over the Atlantic and will be coordinated with NOAA scientists.To address objective 2), the Principal Investigators will use the University of Miami's vortex following, multi-nested, non-hydrostatic mesoscale model (MM5) coupled with a wave model and an ocean model to carry out 3-7 day long integrations showing the evolution and fine structures of the hurricane inner-core and rain-bands at 1-2 km grid resolution. Consistency of the model simulations with the airborne radar and dropsonde data will be sought. Near real-time simulations will be done for cases investigated in the 2005 field program. This study will contribute to the societal goal of improving predictions of hurricanes and associated extreme wind and flash flood events that have a devastating impact on life and property in the U. S. coastal regions.