Impacts of Multiscale FACs on the Ionosphere‐Thermosphere System: GITM Simulation
Impacts of Multiscale FACs on the Ionosphere‐Thermosphere System: GITM Simulation
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多尺度 FAC 对电离层-热层系统的影响：GITM 模拟
DOI：
10.1029/2018ja026082
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发表时间：
2019
期刊：
影响因子：
--
通讯作者：
A. Maute
中科院分区：
文献类型：
--
作者：
Qingyu Zhu;Yue Deng;A. Richmond;R. McGranaghan;A. Maute
在这项研究中，通过分析来自Swarm卫星的FAC数据和来自Dynamic Explorer 2的电场数据，分别在所有季节和所有太阳风条件下以及不同的太阳活动水平下，研究了不同空间尺度上的场向电流（FAC）和电离层电场。FAC和电场的平均和可变分量的分布是本研究的主要重点，其中FAC的变异性表示为FAC在每个磁纬度/磁当地时间仓的标准偏差和电场变异性表示为磁场的东向和赤道向分量的标准偏差的平方和的平方根。我们发现，FAC和电场的平均图案主要由大尺度（波长：500 km）FAC和电场贡献。与平均值不同的是，除了大尺度外，FAC和电场的变率在中尺度（波长：100-500 km）和小尺度（波长：8-100 km）上都不可忽略，而FAC变率显示出与电场变率不同的尺度依赖性。具体而言，对于减小的尺度大小，FAC的可变性增加，而电场的可变性减少，这表明，在小尺度和中尺度上的强FACs不一定对应于这些尺度上的强电离层电场。此外，在大尺度和中尺度的FAC变率被纳入全球电离层热层模式（GITM）和相应的焦耳加热的影响进行了评估。结果发现，对于这里研究的条件，大尺度FAC变化可能会显着增加焦耳加热（全球约160%），并且由于中尺度FAC变化引起的增强不可忽略（全球约36%）。
In this study, field‐aligned currents (FACs) and ionospheric electric fields on different spatial scales are investigated through the analysis of FAC data from the Swarm satellites and electric field data from the Dynamic Explorer 2, respectively, from all seasons and under all solar wind conditions and varying levels of solar activity. Distributions of the average and variable components of FAC and electric field are the main focuses of this study, where the FAC variability is represented by the standard deviation of FAC in each magnetic latitude/magnetic local time bin and electric field variability is represented by the square root of the sum of squares of standard deviations of magnetic eastward and equatorward components of the electric field. We found that the mean patterns of the FAC and electric field are mainly contributed by the large‐scale (wavelength: ⩾500 km) FAC and electric field. Unlike the average, in addition to the large scale, variabilities of FAC and electric field are not negligible on mesoscale (wavelength: 100–500 km) and small scale (wavelength: 8–100 km), while the FAC variability shows a different scale dependence from the electric field variability. Specifically, for decreasing scale sizes, the FAC variability increases while the electric field variability decreases, suggesting that the strong FACs on small scale and mesoscale do not necessarily correspond to strong ionospheric electric fields on those scales. Further, FAC variabilities on large scale and mesoscale are included into the Global Ionosphere Thermosphere Model (GITM) and the corresponding impacts on Joule heating have been assessed. It was found that, for the conditions studied here, the large‐scale FAC variability may significantly increase the Joule heating (~160% globally) and that the enhancement due to the mesoscale FAC variability is not negligible (~36% globally).