Collaborative Research: Intermediate Scale Structures in the Auroral Oval and the Ionospheric Trough

该项目旨在调查极光赤道边缘和中纬度海槽中出现的中尺度不规则现象的发生和分布。美国东北部的六个无源无线电信标接收器网络将用于组装数据库，然后对该数据库进行询问以确定中等规模结构的形态。 一个特定的目标是确定结构的纬向变化与源区（例如极光椭圆形或海槽）以及地磁活动水平的关系。 该数据库包括总电子含量 (TEC)、相位闪烁和 TEC 波动率的测量值，这些测量值将通过监测低地球轨道卫星 150 MHz 和 400 MHz 的无线电信标传输来获得。 用于调查的五个接收器已经存在；该项目寻求在纽约州北部建立第六个接收器。 接收器为相干电离层多普勒接收器（CIDR），该项目下建立的六个CIDR网络将构成东北CIDR阵列（NECA）。其中四个接收器位于康奈尔大学、纽约州立大学奥尼昂塔分校、锡耶纳学院和麻省理工学院。 它们分布在地磁纬度北约 54 度的经线约 400 公里范围内。这种阵列配置能够测量中等尺度等离子体不规则性的发生和空间分布特征，尺寸范围为 100 m 到 30 km。南部的 CIDR 已部署在南磁纬度约 4 度的瓦洛普斯岛，第六个 CIDR 将于 2007 年秋季在纽约州北部的阿迪朗达克山脉（北磁纬度 2 度）建立。来自接收器的数据将用于确定观测到的闪烁和波动的大致高度。一旦确定了大致高度，观测到的闪烁就可以定位在地磁纬度和经度上，以及相对于极光椭圆、电离层槽和风暴增强密度（SED）羽流的位置。 该项目更广泛的影响是教育和社会方面的。 这项调查将有助于确定特别影响地球和近地空间技术的空间天气过程的原因。 电离层不规则性会在无线电通信和导航系统中产生闪烁，并在雷达信号中产生“杂波”。此类系统在航空旅行业中无处不在。由于极光椭圆形和电离层槽附近的航空旅行水平不断增加，这些区域等离子体不规则性的形态和发生具有社会意义和科学价值。 将建立一个中央数据库来存储所有 NECA 的观测结果，该数据库将免费公开提供。 该项目将让本科生参与调查的各个方面，包括数据采集、归档、处理和质量控制。这将使参与的学生熟悉仪器和数据并发展他们的科技能力。

The project aims to investigate the occurrence and distribution of intermediate scale irregularities that develop on the equatorward edge of the aurora and in the midlatitude trough. A network of six passive radio beacon receivers in the northeast United States will be used to assemble a database which will then be interrogated to establish the morphology of the intermediate scale structures. A particular goal is to determine the relation of the zonal variations of the structures to the source region, such as the auroral oval or the trough, and to the level of geomagnetic activity. The database comprises measurements of the total electron content (TEC), phase scintillations, and the rate of TEC fluctuations which will be obtained by monitoring radio beacon transmissions at 150 MHz and 400 MHz from low-Earth-orbiting satellites. Five of the receivers to be used in the investigation already exist; the project seeks to establish a sixth receiver in upstate New York. The receivers are Coherent Ionospheric Doppler Receivers, or CIDRs, and the network of six CIDRs established under this project will constitute the North East CIDR Array (NECA). The locations of four of the receivers are Cornell, SUNY-Oneonta, Siena College, and MIT. These are distributed over about 400 km of longitude at a geomagnetic latitude of ~54 degrees north. This array configuration enables measurements of the occurrence and spatial distribution characteristics of intermediate scale plasma irregularities, ranging in size from 100 m to 30 km. A southern CIDR has been deployed at Wallops Island, at roughly 4 degrees southern magnetic latitude, and a sixth CIDR will be established in the Adirondacks of Northern New York (2 degrees north magnetic latitude) in the fall of 2007. Data from the receivers will be used to determine the approximate altitude of observed scintillations and fluctuations. Once the approximate altitude has been determined, the observed scintillation can be located in geomagnetic latitude and longitude, as well as in position relative to the auroral oval, the ionospheric trough, and the storm enhanced density (SED) plumes. The broader impacts of the project are both educational and societal. The investigation will contribute to the determination of causes of space weather processes that specifically impact technologies on Earth and in near-Earth space. Ionospheric irregularities produce scintillation in radio communication and navigation systems and generate "clutter" in radar signals. Such systems are ubiquitous in the air travel industry. Since there are increasing levels of air travel near the auroral oval and ionospheric trough, the morphology and occurrence of plasma irregularities in these regions has societal implications as well as scientific merit. A central database will be established to store all the NECA observations which will be freely and publicly available. The project will involve undergraduates in all aspects of the investigation, including data acquisition, archiving, processing, and quality control. This will enable participating students to become familiar with the instrumentation and data as well as develop their scientific and technological competence.