Studies of Plasmashere Boundary Layer with Distributed Arrays of Radio Instruments

分布式无线电仪器阵列等离子体边界层研究

• 批准号: 0856093
• 负责人: Anthea Coster
• 金额: $ 47.07万
• 依托单位: Massachusetts Institute of Technology
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2013-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0856093&HistoricalAwards=false
• 关键词: Studies; Plasmashere; Boundary; Layer; Distributed

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).The plasmasphere boundary layer (PBL) is a critical region for dynamic processes in the mid-latitudes that couple the Earth's ionosphere and magnetosphere. It is the region which separates two distinct plasma flow regimes, one convecting sunward, the other co-rotating with the Earth. Some of the consequences of the dynamics in this region are the development of electric fields which couple the ionosphere, plasmasphere, and magnetosphere, the structuring and redistribution of thermal plasmas, and the formation of different scale-sizes of irregularities. Understanding the nature of PBL phenomena, including their magnitude and spatial and temporal characteristics, is critical to characterizing the PBL region and its underlying geophysics. The primary research goal of this project is to experimentally investigate the PBL to characterize its electron density gradients, perturbations, flows, and electric fields from micro to meso-scales (meters to 1000 km) under a range of geomagnetic conditions. A secondary goal of the project is to develop and investigate the capabilities of distributed arrays of small radio instruments for observations of the ionosphere. These investigations will continue through the upcoming rising phase of the solar cycle. The primary scientific questions that will be addressed are: 1) where and how often do density irregularities form at mid-latitudes that result in scintillation?, 2) is there a seasonal, longitudinal, or solar cycle dependence in the development of mid-latitude storm enhanced density (SED) features during geomagnetically disturbed conditions?, and 3) what are the strengths and variations of PBL electric fields, and how do they vary with geomagnetic conditions? This research will exploit existing distributed instrument arrays during the rising phase of the solar cycle to make unique experimental observations in a collaborative campaign oriented approach. Data will be obtained both from the Global Positioning System (GPS) receiver network and from the recently deployed Intercepted Signals for Ionospheric Science (ISIS) array. The GPS network provides total electron content (TEC) information available from many locations around the world. The ISIS array is based on high performance coherent software radio receivers which can intercept a wide range of signals with extremely precise time and frequency synchronization. The intercepted signals can be used for propagation studies, spectrum monitoring, scintillation observations, passive radar, and multistatic active radar. The intent is to establish the utility of distributed arrays of scientific instruments, such as GPS and ISIS, in system-science investigations of the atmosphere. Distributed arrays enable the visualization of atmospheric information with high spatial and temporal resolution over large areas. The broader impacts of the project are several. Several of the research activities will be incorporated into existing educational programs at the MIT Haystack Observatory, including the research experience for undergraduates (REU), the research experience for teachers (RET), and high school internships. Some of the areas of student effort include high performance computing, real-time signal processing, and scientific data mining. ISIS nodes are located at Cornell University, Siena College, Dartmouth College, and University of Washington and the research will enhance collaboration and educational outreach activities at these institutions. Additional impacts of this research include the creation of a large database of ionospheric observations. Both the ISIS array and GPS TEC mapping will provide diagnostics which aid understanding of the space weather impact of sharp TEC gradients.

该奖项是根据2009年美国复苏和再投资法案（公法111-5）资助的。等离子体边界层（PBL）是中纬度地区耦合地球电离层和磁层的动态过程的关键区域。这是两个不同的等离子体流的区域，一个对流向阳，其他与地球共同旋转。在这一地区的动态的一些后果是电场的发展，耦合电离层，等离子体，和磁层，热等离子体的结构和重新分布，并形成不同的规模大小的不规则性。了解边界层现象的性质，包括其规模和时空特征，是描述边界层区域及其基础物理学的关键。该项目的主要研究目标是对边界层进行实验研究，以表征其在一系列地磁条件下从微观到中尺度（米到1000公里）的电子密度梯度、扰动、流动和电场。该项目的第二个目标是开发和研究小型无线电仪器分布式阵列观测电离层的能力。这些调查将在即将到来的太阳活动周期上升阶段继续进行。 将解决的主要科学问题是：1）在中纬度地区，导致闪烁的密度不规则性在哪里形成？2)在地磁扰动条件下，中纬度风暴增强密度（SED）特征的发展是否存在季节性、纵向或太阳周期依赖性？3）边界层电场的强度和变化，以及它们如何随地磁条件变化？这项研究将利用现有的分布式仪器阵列在太阳活动周期的上升阶段，使独特的实验观测在一个合作的活动为导向的方法。将从全球定位系统接收器网络和最近部署的电离层科学截获信号阵列获得数据。全球定位系统网络提供全世界许多地点的总电子含量（TEC）信息。ISIS阵列基于高性能相干软件无线电接收机，可以拦截具有极其精确的时间和频率同步的各种信号。截获的信号可用于传播研究、频谱监测、闪烁观测、无源雷达和多基地有源雷达。其目的是确定全球定位系统和综合信息系统等分布式科学仪器阵列在大气层系统科学调查中的效用。分布式阵列能够以高空间和时间分辨率在大面积上实现大气信息的可视化。该项目的广泛影响有几个。 一些研究活动将被纳入麻省理工学院干草堆天文台现有的教育计划，包括本科生的研究经验（REU），教师的研究经验（RET）和高中实习。学生努力的一些领域包括高性能计算，实时信号处理和科学数据挖掘。 ISIS的节点设在康奈尔大学、锡耶纳学院、达特茅斯学院和华盛顿大学，研究将加强这些机构的合作和教育推广活动。这项研究的其他影响包括创建一个大型电离层观测数据库。ISIS阵列和全球定位系统TEC绘图都将提供诊断，有助于了解TEC急剧梯度对空间气象的影响。