Effects of Large-Scale Flow on the Core Structure of Hurricanes

这项研究计划将研究大规模环流控制大西洋飓风强烈核心区域结构和强度的方式。 该项目将侧重于诊断，但将包含一个数字建模组件。 观测研究将利用研究飞机提供的数据分析飓风眼墙区域风、雨和涡度分布的对称和不对称特征。 数据来源将包括沿飞行路径的沿着现场测量、雷达反射率和多普勒雷达测量以及下投式温探空仪数据。 dropwinsonde数据至关重要，因为它们将允许分析从核心向外扩展到1，000 - 2，000公里半径，由于风暴与环境的相互作用，该区域的流场与全球分析场所解析的流场有很大差异。研究的数值模拟部分将主要是试验性工作，并将使用宾夕法尼亚州立大学NCAR中尺度模式（MM 5）的非静力版本三重嵌套网格。 最内层的网格尺寸为5公里（最后一次为3公里），该网格上的湿对流过程将用显式湿度方案解决。 模拟将使用来自作为研究观察部分的一部分进行分析的病例子集的数据进行初始化。 交互使用数值模拟和对飞机和大规模数据的诊断分析，将能够详细研究大规模气流与飓风核心的强度和结构之间的相互作用性质。由于随着飓风预报所关注的时间尺度（0-5天），大规模气流的预测越来越准确，确定大规模气流控制风、雨和核心相关现象的强度和分布的方式，应能提高这些重要数量的可预测性。

This research program will examine the manner in which large-scale circulations control thc structure and intensity of the intense core regions of Atlantic hurricanes. The project will focus on diagnostics, but will contain a numerical modeling component. The observational study will use data from research aircraft to analyze symmetric and asymmetric features of the distributions of wind, rain and vorticity in the hurricane eyewall region. Data sources will include in-situ measurements along the flight path, radar reflectivity and Doppler radar measurements, and dropwinsonde data. The dropwinsonde data are crucial as they will allow the analyses to be extended outward from the core to 1,000-2,000 km radius, a region in which the flow differs significantly from that resolved by global analysis fields due to storm-environmental interactions.The numerical modeling portion of the study will primarily be a pilot effort and will use the nonhydrostatic version of the Penn State NCAR Mesoscale Model (MM5) with triply nested grids. The innermost mesh size will be 5 km (with some final runs at 3 km), and moist convective processes on this mesh will be resolved with the explicit moisture scheme. The simulations will be initialized with data from a subset of the cases analyzed as part of the observational component of the study. The interactive use of numerical simulations and diagnostic analyses of aircraft and large-scale data will allow detailed study of the nature of interactions between the large-scale flow and the intensity and structure of the hurricane's core. Since the large-scale flow is becoming increasingly well predicted over time scales of interest to hurricane forecasting (0-5 days), determining the manner in which the large-scale flow controls the intensity and the distribution of wind, rain and related phenomena in the core should lead to improved predictability of these important quantities.