In this study, we have derived field-aligned currents (FACs) from magnetometers onboard the Defense Meteorological Satellite Project (DMSP) satellites. The magnetic latitude versus local time distribution of FACs from DMSP shows comparable dependences with previous findings on the intensity and orientation of interplanetary magnetic field (IMF) B y and B z components, which confirms the reliability of DMSP FAC data set. With simultaneous measurements of precipitating particles from DMSP, we further investigate the relation between large-scale FACs and precipitating particles. Our result shows that precipitation electron and ion fluxes both increase in magnitude and extend to lower latitude for enhanced southward IMF B z , which is similar to the behavior of FACs. Under weak northward and southward B z conditions, the locations of the R2 current maxima, at both dusk and dawn sides and in both hemispheres, are found to be close to the maxima of the particle energy fluxes; while for the same IMF conditions, R1 currents are displaced further to the respective particle flux peaks. Largest displacement (about 3.5°) is found between the downward R1 current and ion flux peak at the dawn side. Our results suggest that there exists systematic differences in locations of electron/ion precipitation and large-scale upward/downward FACs. As outlined by the statistical mean of these two parameters, the FAC peaks enclose the particle energy flux peaks in an auroral band at both dusk and dawn sides. Our comparisons also found that particle precipitation at dawn and dusk and in both hemispheres maximizes near the mean R2 current peaks. The particle precipitation flux maxima closer to the R1 current peaks are lower in magnitude. This is opposite to the known feature that R1 currents are on average stronger than R2 currents.

中文翻译：

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大尺度电离层场对齐电流与电子/离子沉淀之间的关系：DMSP 观测

在这项研究中，我们从国防气象卫星项目 (DMSP) 卫星上的磁力计得出了场对齐电流 (FAC)。来自 DMSP 的 FAC 的磁纬度与本地​​时间分布显示出与先前对行星际磁场 (IMF) B y 和 B z 分量的强度和方向的发现具有可比的依赖性，这证实了 DMSP FAC 数据集的可靠性。通过同时测量来自 DMSP 的沉淀颗粒，我们进一步研究了大尺度 FAC 与沉淀颗粒之间的关系。我们的结果表明，降水电子和离子通量都增加了幅度并扩展到低纬度以增强向南的 IMF B z ，这与 FAC 的行为相似。在向北和向南 B z 弱的条件下，发现 R2 电流最大值的位置，在黄昏和黎明两侧以及在两个半球，都接近粒子能量通量的最大值；而对于相同的 IMF 条件，R1 电流进一步移动到各自的粒子通量峰值。在黎明侧向下的 R1 电流和离子通量峰值之间发现了最大的位移（约 3.5°）。我们的研究结果表明，电子/离子沉淀的位置和大规模向上/向下的 FAC 存在系统差异。正如这两个参数的统计平均值所概述的那样，FAC 峰值包含了黄昏和黎明两侧的极光带中的粒子能量通量峰值。我们的比较还发现，黎明和黄昏以及两个半球的粒子降水在平均 R2 电流峰值附近最大化。更接近 R1 电流峰值的粒子沉淀通量最大值在幅度上较低。这与 R1 电流平均强于 R2 电流的已知特征相反。