Doppler Radar Observations and Ensemble-Based Data Assimilation for Cloud-Resolving Hurricane Prediction

该奖项是根据2009年《美国复苏和再投资法案》(公法111-5)资助的。尽管在短期飓风路径预测方面取得了重大进展，但在过去十年中，在预测飓风强度和降雨量方面几乎没有任何改进，在热带气旋形成、快速加强或衰减的数值预测方面也存在非常有限的技能。目前尚不清楚数值预报技能的缺乏是源于不完善的初始条件、不充分的数据同化技术、不完善的预报模式，还是源于混沌动力学的内在可预测性限制。这项研究将使用基于集合的数据同化(ENDA)来探索热带气旋的初始化和预测，以及飓风结构和强度的可预测性的基本限制。这项研究将利用在雨带和强度实验(RAINEX)期间收集的关于2005年三次飓风(卡特里娜、奥菲莉亚和丽塔)的特殊数据集。RAINEX是NSF/NOAA的一个联合实地项目，它使用了多架具有多普勒雷达和投射探测仪能力的飞机，以调查与眼壁-雨带相互作用相关的飓风强度变化。其他将接受审查的案件包括艾米丽(2005年)、威尔玛(2005年)和汉贝托(2007年)。所有这些选定的案例都有广泛和独特的多普勒雷达观测，这些观测是在飓风的整个生命周期中收集的。这项研究的主要目标包括：(1)除常规和实验性的现场和遥感观测外，评估同化地面和机载雷达观测对可预报性的影响；(2)探索大尺度环境和内部动力学，包括湿对流，对飓风结构和强度变化的可预报性的作用；(3)通过模拟观测和实际观测的观测系统数值试验，评估不同观测平台和目标策略对飓风预测的影响和有效性。知识优势：ENDA技术与现场观测相结合，在数据同化和理解热带气旋的动力学、强度、结构、预报和可预报的基本限度方面可能取得重大进展。这项工作也将为今后的观测网络设计和观测策略提供指导。更广泛的影响：这项研究将通过博士后研究生和博士后科学家的广泛参与来提供教育效益。研究成果将用于高级教育课程和本科生研究项目。所获得的关于飓风的可预测性的知识可能会使业务界和普通公众受益。ENDA技术和计算机代码将免费在网上提供，并提供大量文件，使更大的学术界受益。

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).Despite significant progress in short-range hurricane track forecasts, over the past decade there has been virtually no improvement in predicting hurricane intensity and amount of precipitation, and very limited skill exists in the numerical prediction of tropical cyclone formation, rapid intensification or decay. It remains unclear whether the lack of numerical forecast skill derives from imperfect initial conditions, inadequate data assimilation techniques, imperfect forecast models, or from intrinsic predictability limits due to chaotic dynamics. This research will use ensemble-based data assimilation (EnDA) to explore the initialization and prediction of tropical cyclones as well as the fundamental limits to the predictability of hurricane structure and intensity. The research will utilize special data sets collected on three 2005 hurricanes (Katrina, Ophelia and Rita) during the Rainband and Intensity Experiment (RAINEX). The RAINEX was a joint NSF/NOAA field project that employed multiple aircraft with Doppler radars and dropsonde capabilities to investigate the hurricane intensity changes that are associated with eyewall-rainband interactions. Other cases to be examined include Emily (2005), Wilma (2005), and Humberto (2007). All of these selected cases have extensive and unique Doppler radar observations that were collected over the lifecycles of the hurricanes. Major objectives of the research include: (1) assess the impacts on predictability of assimilating ground-based and airborne radar observations in addition to regular and experimental in-situ and remotely sensed observations; (2) explore the role of the large-scale environment and internal dynamics, including moist convection, on the predictability of hurricane structure and intensity change; and (3) evaluate the impact and effectiveness of different observing platforms and targeting strategies on hurricane prediction through observing system numerical experiments with both simulated and actual observations. Intellectual merit: The combination of the EnDA technique with field observations constitutes a potentially significant advance in data assimilation and understanding of dynamics, intensity, structure, prediction, and fundamental limits of predictability of tropical cyclones. The work will also may provide guidance for future observing network design and observing strategy. Broader impacts: The research will provide educational benefits through the extensive participation of a doctoral graduate student and a postdoctoral scientist. Research findings will be used in advanced educational courses and undergraduate research projects. Knowledge gained about the predictability of hurricanes potentially will benefit the operational communities and the general public. The EnDA techniques and computer codes will be made freely available online with ample documentation to benefit the larger academic community.