A high‐resolution model of field‐aligned currents through empirical orthogonal functions analysis (MFACE)
A high‐resolution model of field‐aligned currents through empirical orthogonal functions analysis (MFACE)
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DOI：
10.1029/2012gl053168
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发表时间：
2012-09
影响因子：
5.2
通讯作者：
M. He;J. Vogt;H. Lühr;E. Sorbalo;A. Blagau;G. Le;G. Lu
中科院分区：
文献类型：
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作者：
M. He;J. Vogt;H. Lühr;E. Sorbalo;A. Blagau;G. Le;G. Lu
十年的CHAMP磁场测量被集成到MFACE中，MFACE是一种使用经验正交函数（EOF）的场向电流（FACs）模型。EOF 1给出了基本的区域-1/区域-2图案，主要随行星际磁场Bz分量而变化。EOF 2分别捕获尖点电流特征和By相关变异性。与现有的模型相比，MFACE产量显着更好的空间分辨率，再现典型的观察FAC的厚度和强度，改善了磁本地时间（MLT）的分布，并给出了FAC纬度和NBZ电流签名的季节依赖性。MFACE进一步揭示了对By的系统依赖性，包括1）中午附近的区域-1/区域-2拓扑结构修改; 2）向上和向下最大电流密度之间的不平衡; 3）Harang不连续的MLT位置。此外，我们的程序可以量化的响应时间的FAC太阳风驱动在弓形激波鼻子：我们得到20分钟和35-40分钟的FAC密度和纬度，分别滞后。
Ten years of CHAMP magnetic field measurements are integrated into MFACE, a model of field‐aligned currents (FACs) using empirical orthogonal functions (EOFs). EOF1 gives the basic Region‐1/Region‐2 pattern varying mainly with the interplanetary magnetic fieldBz component. EOF2 captures separately the cusp current signature and By‐related variability. Compared to existing models, MFACE yields significantly better spatial resolution, reproduces typically observed FAC thickness and intensity, improves on the magnetic local time (MLT) distribution, and gives the seasonal dependence of FAC latitudes and the NBZ current signature. MFACE further reveals systematic dependences on By, including 1) Region‐1/Region‐2 topology modifications around noon; 2) imbalance between upward and downward maximum current density; 3)MLT location of the Harang discontinuity. Furthermore, our procedure allows quantifying response times of FACs to solar wind driving at the bow shock nose: we obtain 20 minutes and 35–40 minutes lags for the FAC density and latitude, respectively.