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

中尺度（0.1-2公里）电离层不规则性对中频/高频无线电波的多重散射理论预测了地面发射机附近电离层反射信号的积分强度的非常独特的分布。特别是，在与磁子午线正交约几十公里的距离内，它明显减小。然后在更远的地方出现一个增强环。在距离发射机较远的地方，多重散射的影响减弱，积分强度恢复到未受干扰的值。在三维空间中，这种依赖的形状类似于倒置的“牛仔帽”。虽然在发射机位置附近有实验证实了这种“异常衰减”效应，但尚未尝试跟踪对“牛仔帽”效应重要的较大距离上的强度特征。这类实验对于理论的证实至关重要，也是本项目的主要目标。探测“牛仔帽”效应需要在几小时内在距离发射机100-200公里范围内的不同地点进行测量。为此目的将使用一个安装在汽车上的装置，包括一个无线电矢量场传感器（瑞典空间物理研究所研制的一种仪器）、一台控制笔记本电脑和一个标准的GPS接收器。任何从电离层提供脉冲反射的中频/高频雷达都将服务于该项目的目的。由位于科罗拉多州普拉特维尔附近的普拉特维尔大气观测站的中频雷达和博尔德电离层探空仪产生的电离层反射将被探索。每个数据采集过程将在汽车沿着东西或南北方向行驶时完成，大约以雷达的纬度或经度为中心，并且足够长，可以穿过牛仔帽的“墙壁”。20至30届会议应足以提供必要的统计数字。该项目的更广泛影响包括在了解与应用各种遥感技术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、空间气象和雪松等重要领域具有潜在的应用前景：在中尺度电离层不规则性的诊断、加热实验的解释、中频/高频和卫星通信中。多重散射理论对等离子体聚变诊断和日冕物理具有重要意义。

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.