Development of Balloon Systems for Continuous Measurement of Hurricane Eye Properties

热带气旋的破坏力随其最大风速呈非线性增加，但对热带气旋强度的直接测量只在一些大西洋风暴中进行，而且每天只进行几次。同时，众所周知，与同心眼壁周期有关的强度波动在至少小至12小时的时间尺度上发生非常大的波动。在除北大西洋以外的世界所有地区，卫星技术都用于估计热带气旋强度。这些技术主要基于可见光和红外图像的云的形状和分布特征，以及红外图像对眼热结构的推断，而红外图像的时间连续性受到极轨道的限制。在评估大西洋区域以外的卫星估计时，几乎没有什么“地面真相”，也没有人声称这种技术能够探测到短周期的强度波动。这项研究是一个两阶段项目的第二阶段，该项目旨在开发一种可在空气中展开的拖曳气球，用于在飓风眼中进行连续测量。在第一阶段，气球系统在受控环境、数值模拟和有限的现场进行了开发和测试。第二阶段的工作将进行广泛的现场测试，并可能在实际飓风中进行试验部署。该系统将连续报告风眼特征的测量结果，包括中心地面压力和海面温度，这是风暴强度的一个重要指标，而海面温度对风暴强度变化有很大影响。该系统将在美国空军定期调查大西洋飓风的C-130侦察机上进行部署。从气球系统获得的数据将首次提供几乎连续的风暴强度记录，帮助研究人员和预报员了解和预测飓风强度的短期变化。这些记录还可以与地球静止卫星提供的几乎连续的风暴特征记录进行比较，以便后者将来可能用于探测飓风强度的短期变化。该项目的最终目标是提供一个载人飞机和无人机可部署的气球系统，用于持续监测全球热带气旋。如果成功，该项目将首次实现对飓风眼特性的连续测量。这将在飞机侦察任务之间为预报员提供有关飓风强度的详细信息，从而帮助他们提供更准确的警告。它还将帮助研究人员描述和理解飓风强度的短期波动。

The destructive potential of tropical cyclones increases nonlinearly with their maximum wind speed, yet direct measurements of tropical cyclone intensity are only made in some Atlantic storms and these are made only a few times per day. At the same time, it is well known that very substantial fluctuations in intensity occur on time scales at least as small as 12 hours in association with concentric eyewall cycles. In all areas of the world except the North Atlantic, satellite-based techniques are used for estimating tropical cyclone intensity. These techniques are based mostly on characteristics of cloud shapes and distributions from visible and infrared imagery, and on inferences about eye thermal structure from infrared imagery whose time continuity is limited by polar orbit restrictions. There is little in the way of "ground truth" for evaluating satellite-based estimates outside the Atlantic region, and no claim has been made that such techniques are capable of detecting short period intensity fluctuations. This research is the second step in a two-phase project to develop an air-deployable drogued balloon for continuous measurements in hurricane eyes. In the first phase, the balloon system was developed and tested in controlled environments, in numerical simulations and, to a limited extent, in the field. The Phase II effort will pursue extensive field testing and potentially the experimental deployment in actual hurricanes. The system will report continuous measurements of eye characteristics, including central surface pressure, which is a strong indicator of storm intensity, and sea surface temperature, which has a strong influence on storm intensity change. The system will be deployed on an opportunistic basis from U.S. Air Force C-130 reconnaissance aircraft that routinely survey Atlantic hurricanes. Data acquired from the balloon system will provide for the first time a nearly continuous record of storm intensity, helping researchers and forecasters understand and predict short period variations in hurricane intensity. Such records can also be compared to the nearly continuous records of storm characteristics available from geostationary satellites, so that potentially the latter can be used in the future to detect short period changes in hurricane intensity. The ultimate goal of this project is to provide a manned aircraft- and UAV-deployable balloon system for continuous monitoring of tropical cyclones worldwide. If successful, this project will lead to the first continuous measurement of hurricane eye properties. This will provide forecasters with detailed information about the intensity of hurricanes in between aircraft reconnaissance missions, thereby helping them to provide more accurate warnings. It will also help researchers characterize and understand short-period fluctuations in hurricane intensity.