Mechanisms for Rapid Intensity Changes in Hurricanes

小行星9714253 美国天气研究计划（USWRP）是一项跨部门活动，旨在执行和实施必要的研究，以改善向国家提供的天气服务。 根据这一方案，国家科学基金会、国家海洋和大气管理局、国家航空航天局和海军研究办公室正在联合评估和支持美国水资源研究计划高度优先的研究。 强风和暴雨！与登陆飓风相关的组织规模比那些可以预测的规模小， 分析和模型。 虽然飓风造成的大部分破坏是由于地核的小规模和迅速变化的特征造成的，但人们对控制风、对流和相关现象变化的物理机制知之甚少。 然而，越来越多的证据表明，在飓风核心观察到的主要变化和不对称性受到可以预测的更大尺度特征的强烈调制。 一个有希望的方法来改善预测的结构和强度的飓风登陆附近是提高我们的定量了解这些因果关系。 该研究计划将使用一系列飓风数值模拟来研究飓风结构和强度在登陆前后变化的机制。 将使用一个最先进的非流体静力学模型来模拟飓风核心的快速小规模变化，因为它对风速、垂直风切变、大规模梯度和位涡异常以及边界层过程的变化作出反应。 这项研究的主要重点将是外部环流和表面特性的变化如何影响飓风的次级环流，从而调节对流的大小和分布。研究还将分析风暴对流中的不对称性，包括螺旋雨带中的对流，对风暴强度和核心结构的影响。 这些结果应能大大提高对飓风结构迅速变化过程的认识，并可立即用于改进对飓风中的风、风暴潮和降雨的预测。 ***

9714253 Frank The U.S. Weather Research Program (USWRP) is an interagency activity designed to perform and implement the research necessary to improve the delivery of weather services to the nation. Under this Program, the National Science Foundation, the National Oceanic and Atmospheric Administration (NOAA), the National Aeronautics and Space Administration and the Office of Naval Research are jointly evaluating and supporting research of high priority to the USWRP. The intense winds and rainfall! associated with landfalling hurricanes are organized on smaller scales than those that can be forecast using currently available analyses and models. Although much of the damage caused by hurricanes results from small-scale and rapidly changing features of the core, the physical mechanisms governing changes in the winds, convection and related phenomena are poorly understood. There is, however, growing evidence that the major changes and asymmetries observed in the cores of hurricanes are strongly modulated by larger- scale features that can be predicted. A promising approach to improving forecasts of the structure and intensity of hurricanes near landfall is to improve our quantitative understanding of these causal relationships. This research program will study the mechanisms by which hurricane structure and intensity vary near and after landfall using a series of numerical simulations of hurricanes. A state-of-the-art non-hydrostatic model will be used to simulate rapid, small-scale variations in the hurricane core as it responds to imposed variations in wind speed, vertical wind shear, large-scale gradients and anomalies of potential vorticity, and changes in boundary layer processes. A primary focus of the study will be on the manner in which the imposed variations in external circulations and surface properties affect the hurricane's secondary circulation, and hence modulate the magnitude and distribution of convection. The re search will also analyze the manner in which asymmetries in the storm convection, including convection in the spiral rainbands, affect the storm's intensity and core structure. The results should provide significantly improved understanding of the processes governing rapid changes in hurricane structure, and they should be of immediate use in improving forecasts of the winds, storm surge and rainfall in hurricanes. ***