CEDAR: Characterizing the Variability in the High Latitude Ionospheric Electric Field

CEDAR：表征高纬度电离层电场的变化

• 批准号: 0836485
• 负责人: Simon Shepherd
• 金额: $ 31.7万
• 依托单位: Dartmouth College
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2008
• 资助国家: 美国
• 起止时间: 2008-12-15 至 2012-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0836485&HistoricalAwards=false
• 关键词: CEDAR; Characterizing; Variability; Latitude; Ionospheric

The high-latitude electric field is one of the most important parameters that influence energy deposition in the form of Joule heating in the upper atmosphere. Numerical models often use statistical or climatological electric-field models which ignore an important component of Joule heating that is due to rapid, small-scale fluctuations in the electric field, or small-scale variability (SSV). Studies attempting to quantify this type of variability using satellite or groundbased incoherent scatter radar measurements have created variability maps associated with statistical electric-field patterns. The variability described in these studies is a different type of variability, namely, climatological model variability (CMV) that describes how well the model reproduces the measurements. The relationship between these two variabilities, and the physical significance of CMV, is presently unknown. This project aims to resolve the ambiguity between CMV and SSV by using data from southern and northern hemisphere SuperDARN radars to develop maps of both CMV (similar to previous studies) and SSV. The latter will be obtained from observations sampled at 1-2 min that are continuous for 10 min. The resulting maps will allow for a direct comparison of the relative magnitudes of CMV and SSV over the entire high-latitude region, providing a clear picture of the physical significance of SSV and CMV in electric fields. By further utilizing the widespread and continuous SuperDARN measurements for specific events, the project obtain additional information that allows the variability measurements to be located relative to large-scale convection and magnetospheric boundaries, providing clues to its origins. The end product of the research should be the resolution of the ambiguity that exists between SSV and CMV, and clarification of the physical significance that CMV plays in the high-latitude ionosphere. Since large-scale convection maps of the high-latitude electric potential are perhaps the most commonly used data product of the SuperDARN HF network, the southern hemisphere statistical patterns resulting from this study will improve the accuracy of the southern hemisphere convection patterns during times when data coverage is not widespread. The availability of hemisphere-specific statistical patterns and variability maps resulting from this project will facilitate studies of the interhemispheric dependencies of various ionospheric and magnetospheric parameters.

高纬电场是影响高空大气焦耳加热能量沉积的重要参数之一。数值模式通常使用统计或气候学电场模式，忽略了焦耳加热的一个重要组成部分，这是由于电场的快速、小尺度波动或小尺度可变性(SSV)造成的。试图使用卫星或地面非相干散射雷达测量来量化这种类型的可变性的研究已经创建了与统计电场模式相关的可变性地图。这些研究中描述的变异性是一种不同类型的变异性，即描述模型再现测量结果的程度的气候模型变异性(CMV)。这两个变量之间的关系，以及CMV的物理意义，目前尚不清楚。该项目旨在通过使用南半球和北半球SuperDARN雷达的数据来绘制CMV(类似于以前的研究)和SSV之间的地图，以解决CMV和SSV之间的模糊性。后者将从连续10分钟的1-2分钟的观察中获得。由此得到的地图将允许直接比较整个高纬度地区的CMV和SSV的相对大小，提供SSV和CMV在电场中的物理意义的清晰图景。通过进一步利用广泛和连续的SuperDARN对具体事件的测量，该项目获得了更多信息，使变异性测量能够相对于大尺度对流和磁层边界进行定位，从而为其起源提供线索。研究的最终结果应该是解决SSV和CMV之间存在的模棱两可的问题，并澄清CMV在高纬度电离层中发挥的物理意义。由于高纬度电势的大尺度对流图可能是SuperDARN HF网络最常用的数据产品，因此，这项研究得出的南半球统计模式将在数据覆盖范围不广的情况下提高南半球对流模式的准确性。该项目所产生的特定半球的统计模式和变化图的提供，将有助于研究各种电离层和磁层参数的半球间相关性。