Systematic Study of Field-aligned Current Sources Based on Satellite Magnetic Field and Particle Precipitation Data

基于卫星磁场和粒子降水数据的场对准电流源系统研究

• 批准号: 0538513
• 负责人: Simon Wing
• 金额: $ 28.34万
• 依托单位: Johns Hopkins University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2005
• 资助国家: 美国
• 起止时间: 2005-12-15 至 2009-11-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0538513&HistoricalAwards=false
• 关键词: Systematic; Study; Field; aligned; Current

Field-aligned currents (FAC) are an essential element of the coupling between the magnetosphere and the ionosphere. This project will statistically examine large-scale FACs and particle precipitation using the magnetic field and particle precipitation data from the DMSP-F7 and -F11 to -F15 satellites. An automatic procedure to identify FAC structures will be applied to the magnetic field data set, which will create a list of nearly 300,000 FAC crossings. Similarly, a method has been developed that can identify particle precipitation regions and boundaries, using the DMSP data set. Combining these two methods will make it possible to define the source regions of FACs. Dayside and nightside FACs will be examined separately. For dayside FACs, issues to be addressed are (1) the occurrence frequency of different precipitation regions in each FAC system (region 2, region 1, and region 0), and the dependence on MLT and FAC polarity; (2) the locations of particle boundaries relative to FAC boundaries; and (3) the dependence of the results on solar wind conditions. Issues to be addressed for nightside FACs are (1) the locations of precipitation boundaries relative to the boundaries of region 1 and region 2 currents, (2) the locations and boundaries for 3-sheet structures of FACs, which are presumably related to the Harang discontinuity in the pre-midnight sector; and (3) dependence of the results on geomagnetic conditions. The project will provide a better understanding of high-latitude particle precipitation, which is an important factor to determine the ionospheric conductivity, and therefore, it will contribute to space weather initiatives such as global modeling and data assimilation.

场向电流（FAC）是磁层与电离层耦合的重要组成部分。该项目将利用DMSP-F7和DMSP-F11至DMSP-F15卫星提供的磁场和粒子沉降数据，对大规模FAC和粒子沉降进行统计研究。将对磁场数据集应用一个自动识别FAC结构的程序，这将产生一个近300 000个FAC交叉点的清单。同样，已经开发出一种方法，可以识别粒子降水区域和边界，使用DMSP数据集。结合这两种方法，将有可能确定的FAC的源极区域。将分别检查昼侧和夜侧FACs。对于昼侧FAC，要解决的问题是（1）在每个FAC系统中不同降水区域（区域2，区域1和区域0）的出现频率，以及对MLT和FAC极性的依赖性;（2）粒子边界相对于FAC边界的位置;（3）结果对太阳风条件的依赖性。夜侧FAC要解决的问题是（1）相对于区域1和区域2电流边界的降水边界的位置，（2）FAC的3片结构的位置和边界，这可能与午夜前扇区的Harang不连续性有关;以及（3）结果对地磁条件的依赖性。该项目将使人们更好地了解高纬度粒子降水，这是确定电离层传导性的一个重要因素，因此，它将有助于全球建模和数据同化等空间气象举措。