CEDAR: Verification of the Theory of Multiple Scattering of High-Frequency (HF) Signals in the Ionosphere with Small-scale Irregularities

中频/高频无线电波被中等尺度（0.1-2公里）电离层不规则体多次散射的理论预测，从地面发射机附近的电离层反射的信号的积分强度分布非常独特。特别是，它在垂直于磁子午线的大约几十公里的距离内显著减少。然后在更远的距离处出现增强环。在离发射器更远的距离处，多次散射的影响减弱，积分强度返回到其未受干扰的值。如在三维中所表示的，这种依赖的形状类似于倒置的“牛仔帽”。虽然在发射器位置附近有这种“异常衰减”效应的实验证实，但还没有尝试在对“牛仔帽”效应重要的较大距离处跟踪强度特征。这种实验对于证实理论至关重要，也是本项目的主要目标。检测“牛仔帽”效应需要能够在几个小时内在距离发射机100-200公里的范围内的各个点进行测量。为此目的将使用一个车载装置，包括一个无线电矢量场传感器（瑞典空间物理研究所开发的仪器）、一台控制用膝上型计算机和一台标准全球定位系统接收器。提供电离层脉冲反射的任何中频/高频雷达都将用于这一项目。将对位于科罗拉多普拉特维尔附近的普拉特维尔大气观测站中频雷达和博尔德电离层探测仪产生的电离层反射进行探索。每个数据采集会话将在西-东或北-南方向的汽车行程中完成，大约以雷达的纬度或经度为中心，并且足够长以穿过牛仔帽的“墙壁”。20至30次会议应足以提供必要的统计数据。该项目的更广泛影响包括在理解与各种遥感技术应用有关的高层大气过程方面取得进展。一名研究生将参与该项目。广播和通信行业及其政府监管机构可以直接使用该项目的成果。多重散射理论在航空学、空间气象和CEDAR社区的重要领域中具有潜在的应用：诊断中等尺度电离层不规则性，解释加热实验，MF/HF和卫星通信。多重散射理论对等离子体聚变诊断和日冕物理学都有影响。

The theory of multiple scattering of MF/HF radio waves by intermediate-scale (0.1-2 km) ionospheric irregularities predicts a very distinctive distribution of the integral intensity of a signal reflected from the ionosphere in the vicinity of a ground-based transmitter. In particular, it is significantly reduced within a distance of about several tens of kilometers orthogonal to the magnetic meridian. There then occurs a ring of enhancement at a greater distance. At still larger distances from the transmitter, effects of multiple scattering are weakened and the integral intensity returns to its undisturbed value. As represented in three dimensions, the shape of this dependence resembles an inverted "cowboy hat". While there are experimental confirmations of this "anomalous attenuation" effect near the transmitter location, no attempt has yet been made to track the intensity features at the larger distances important for the "Cowboy Hat" effect. An experiment of this kind is critical for confirmation of the theory, and it is the main objective of this project. Detection of the "Cowboy Hat" effect requires an ability to perform measurements at various points within 100-200 km distances from the transmitter in a matter of hours. An automobile-mounted installation will be used for this purpose, comprising a Radio Vector Field Sensor (an instrument developed by the Swedish Institute of Space Physics), a controlling laptop computer, and a standard GPS receiver. Any MF/HF radar providing pulse reflections from the ionosphere will serve the purposes of this project. Ionospheric reflections produced by the MF radar of the Platteville Atmospheric Observatory located near Platteville, Colorado and by the Boulder ionosonde will be explored. Each data acquisition session will be done during car journeys in the West-East or North-South directions, centered approximately at the radar's latitude or longitude and long enough to cross the Cowboy Hat's" walls. Twenty to thirty sessions should be sufficient to provide the necessary statistics. Broader impacts of the project include advances in understanding of processes in the upper atmosphere related to application of various remote sensing techniques. A graduate student will participate in the project. The broadcast and communications industries and their government regulators can directly use results of this project. The theory of multiple scattering has potential applications in fields important for the Aeronomic, Space-Weather and CEDAR communities: in diagnostics of intermediate-scale ionospheric irregularities, in interpretation of heating experiments, in MF/HF and satellite communications. There are implications of multiple scattering theory for plasma fusion diagnostics and for the physics of the solar corona.