Interaction Between Landfalling Hurricanes and the Atmospheric Boundary Layer Using Ensemble-based Data Assimilation

准确预测登陆时飓风的强度和结构可以挽救生命，减轻社会影响。然而，在最近改进飓风预报的努力中，很少有研究专注于登陆飓风。这反映了预测飓风登陆的复杂性，以及在数值天气预报(NWP)模式中表示大气边界层条件的不确定性。本研究的目的是利用基于集合的资料同化方法研究登陆飓风与大气边界层之间的相互作用。研究基于两个假设：1)飓风与大气边界层之间的相互作用是控制登陆飓风强度和结构变化的重要因素；2)地面中尺度和WSR-88D多普勒雷达观测的集合同化将改善与登陆飓风相互作用的近地面和边界层大气条件的表示。因此，这项研究将把地面中尺度和多普勒雷达观测与其他可用的常规和卫星数据合并为一个集合数据同化系统和社区中尺度天气研究和预报(WRF)模式。将讨论以下四个科学问题：1.飓风在登陆过程中结构如何演变？2.大气边界层环境条件如何以及在多大程度上影响登陆飓风的强度和结构？3.飓风涡旋和二次环流如何与大气边界层环境条件相互作用？4.控制登陆飓风强度和结构变化的过程是什么？智力价值：这项研究是首次利用基于集合的数据同化来全面研究登陆飓风和大气边界层之间的相互作用以及登陆飓风的可预测性。这项研究的结果有望增进我们对登陆飓风的了解，也有助于我们科学界改进飓风强度预测的总体目标。广泛影响：这项研究的结果将有助于准确预测登陆时的飓风及其相关的极端风和洪水降雨事件，这些事件对美国沿海地区的社会和环境造成破坏性影响。更广泛的影响还将延伸到教育目标，因为研究生将在本研究期间接受培训。

Accurate forecasts of the intensity and structure of a hurricane at landfall can save lives and mitigate social impacts. However, among recent efforts in hurricane forecast improvements, few studies have focused on landfalling hurricanes. This reflects the complexity of predicting hurricane landfalls and the uncertainties in representing the atmospheric boundary layer conditions in numerical weather prediction (NWP) models. The aim of this study is to investigate the interaction between landfalling hurricanes and the atmospheric boundary layer using ensemble-based data assimilation.The study is based on two hypotheses: 1) the interaction between the hurricane and atmospheric boundary layer is an essential factor that controls the intensity and structure changes of landfalling hurricanes; and 2) the ensemble assimilation of surface mesonet and WSR-88D Doppler radar observations will improve the representation of near surface and boundary layer atmospheric conditions that interact with the landfalling hurricanes. Therefore, the research will incorporate the surface mesonet and Doppler radar observations with other available conventional and satellite data into an ensemble data assimilation system with the community mesoscale weather research and forecasting (WRF) model. The following four scientific questions will be addressed:1. How does a hurricane's structure evolve during its landfall?2. How, and to what extent, do atmospheric boundary layer environmental conditions influence the intensity and structure of landfalling hurricanes?3. How do the hurricane vortex and secondary circulation interact with the atmospheric boundary layer environmental conditions? 4. What are the processes that control the intensity and structural changes of landfalling hurricanes?Intellectual Merit: The research represents the first comprehensive study of the interaction between landfalling hurricanes and the atmospheric boundary layer as well as the predictability of landfalling hurricanes using ensemble-based data assimilation. Results from this study are expected to enhance our understanding of landfalling hurricanes and also contribute to the overall goals of our scientific community in improving hurricane intensity forecasts.Broader Impacts: Results from this study will facilitate the accurate prediction of hurricanes at landfall as well as their associated extreme winds and flooding rainfall events that have devastating effects on society and the environment in U.S. coastal regions. The broader impacts will also extend to educational goals, as graduate students will be trained during this research.