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

场向电流（FAC）是磁层和电离层之间耦合的一个重要因素。该项目将利用DMSP-F7和-F11至-F15卫星的磁场和颗粒降水数据，对大规模fas和颗粒降水进行统计研究。识别FAC结构的自动程序将应用于磁场数据集，这将创建一个近30万个FAC交叉点的列表。类似地，已经开发出一种方法，可以使用DMSP数据集识别颗粒降水区域和边界。将这两种方法结合起来，就有可能确定fac的来源区域。昼侧和夜侧FACs将分别进行检查。对于昼侧FAC，需要解决的问题是：(1)每个FAC系统中不同降水区域（2区、1区和0区）的发生频率，以及对MLT和FAC极性的依赖；(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。夜侧地面站需要解决的问题是：(1)降水边界相对于区域1和区域2水流边界的位置，(2)地面站三层结构的位置和边界，这可能与午夜前扇区的Harang不连续有关；(3)结果与地磁条件的关系。该项目将更好地了解高纬度粒子降水，这是决定电离层电导率的一个重要因素，因此，它将有助于空间天气倡议，如全球建模和数据同化。

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.