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)电离层不规则性多次散射的理论预测了地面发射机附近电离层反射的信号积分强度的非常独特的分布。特别是，在与磁子午线垂直的大约几十公里的距离内，它被显著地减小。然后，在更远的距离上出现了一个增强环。在距离发射机更远的地方，多次散射的影响减弱，积分强度恢复到其未受干扰的值。如三个维度所示，这种依赖的形状就像一顶倒置的“牛仔帽”。虽然有实验证实了发射机位置附近的这种“异常衰减”效应，但还没有人试图追踪对“牛仔帽”效应很重要的较大距离的强度特征。这类实验是验证理论的关键，也是本项目的主要目标。探测“牛仔帽”效应需要在几个小时内在距离发射机100-200公里范围内的不同点进行测量。为此将使用车载装置，包括无线电矢量场传感器(瑞典空间物理研究所开发的仪器)、控制笔记本电脑和标准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。将探索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MF雷达和Boulder电离层探空仪产生的电离层反射。每一次数据采集都将在汽车向西-东或北-南方向行驶时进行，大致以雷达的纬度或经度为中心，并有足够的长度穿过牛仔帽的“墙”。二十至三十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各种遥感技术的应用有关的高层大气过程方面取得的进展。一名研究生将参与这个项目。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。多重散射理论在对航空、空间天气和雪松群落具有重要意义的领域具有潜在的应用：中等尺度电离层不规则的诊断、加热实验的解释、中频/高频和卫星通信。多重散射理论对等离子体聚变诊断学和日冕物理学具有重要意义。

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.