Determining the boundaries of the auroral oval from CHAMP field-aligned current signatures – Part 1
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In this paper, the first statistical study on auroral oval boundaries derived from small and medium-scale field-aligned currents (FACs) was presented, and the results were used for the first time.Abstract:
. In this paper we present the first statistical study on auroral oval boundaries derived from small- and medium-scale field-aligned currents (FACs,read more
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Extremely Collimated Electron Beams in the High Latitude Magnetosphere Observed by Arase
Yoichi Kazama,Hirotsugu Kojima,Yoshizumi Miyoshi,Yoshiya Kasahara,Shigeru Kasahara,Hideyuki Usui,B. J. Wang,B. J. Wang,Shiang-Yu Wang,Sunny W. Y. Tam,T. F. Chang,Kazushi Asamura,Yasumasa Kasaba,Shoya Matsuda,Masafumi Shoji,Ayako Matsuoka,Mariko Teramoto,Takeshi Takashima,Iku Shinohara +18 more
Journal ArticleDOI
Statistical maps of field-aligned currents inferred from Swarm: Dependence on season and interplanetary magnetic field
TL;DR: In this article, the initial results of the statistical analysis of field-aligned currents (FACs) observed above the ionosphere by the low-Earth polar-orbiting Swarm satellite are reported.
Journal ArticleDOI
Correlation analysis of field-aligned currents from the magnetic measurements of GRACE follow-on mission
Chao Xiong,Claudia Stolle,Ingo Michaelis,Hermann Lühr,Yun-Liang Zhou,Hui Wang,Guram Kervalishvili,Jan Rauberg +7 more
Abstract: In this study we performed a detailed analysis on the scale-size of field-aligned currents (FACs) at auroral latitudes, using the well-calibrated magnetic data from the non-dedicated magnetic field mission, Gravity Recovery and Climate Experiment Follow-On (GRACE-FO). With two spacecraft following each other, the GRACE-FO provides a good opportunity to identify the variation of FACs with different scale lengths. The results show that the auroral FACs can be classified into two groups: the small-scale ones, shorter than some tens of kilometers, dominated by kinetic Alfven waves, are quite dynamic; and the large-scale ones, typically larger than 150 km, can be considered as quasi-static and persist longer than 1 min. The GRACE-FO observations also reveal that the small-scale FACs at the same location sometimes can persist over 25 s, e.g., around dusk and dawn hours, which is longer than the typical persistent period (10 s) of kinetic Alfven waves as earlier reported. The FAC structures show clear magnetic local time dependence, with higher correlations between the spacecraft around dusk and dawn hours; lower correlations are found around midnight and lowest correlations around noon, implying that the small-scale FACs most frequently appear at the noon cusp region. Slightly better correlations of FACs between two spacecraft are found during local summer, and such seasonal dependence is dominated by the correlations of small-scale FACs at noon. However, further analysis shows that the small-scale FACs at noon have largest occurrence and intensity during local summer, which reveals that when interpreting the cross-correlation analysis the intensity of FACs needs to be taken into account.
References
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Large‐scale characteristics of field‐aligned currents associated with substorms
T. Iijima,T. A. Potemra +1 more
TL;DR: In this paper, the authors determined the statistical features of field-aligned currents during a large number of substorms from the magnetic field observations acquired with the Triad satellite, including the following: (1) the large-scale regions of fieldaligned currents determined previously by the authors (Iijima and Potemra, 1976a) persist during all phases of sub-storm activity, namely, region 1, located near the poleward boundary of the fieldaligned current region, and region 2, positioned near the equatorward boundary.
Journal ArticleDOI
Ionospheric Electrodynamics Using Magnetic Apex Coordinates.
TL;DR: In this paper, the equations of ionospheric electrodynamics are developed for a geomagnetic field of general configuration, with specific application to coordinate systems based on Magnetic Apex Coordinates.
Journal ArticleDOI
Field‐aligned currents in the dayside cusp observed by Triad
T. Iijima,T. A. Potemra +1 more
TL;DR: The characteristics of field-aligned currents at an altitude of 800 km in the dayside highlatitude region over the northern hemisphere were determined from the Triad satellite magnetometer data recorded at College, Alaska, from January 1973 to October 1974 as mentioned in this paper.
Journal ArticleDOI
A nearly universal solar wind-magnetosphere coupling function inferred from 10 magnetospheric state variables
TL;DR: In this article, the authors investigated whether one or a few coupling functions can represent best the interaction between the solar wind and the magnetosphere over a wide variety of magnetospheric activity.
Journal ArticleDOI
A statistical model of auroral electron precipitation
TL;DR: In this article, the average characteristics of auroral electron precipitation as a function of magnetic local time, magnetic latitude, and geomagnetic activity as measured by Kp were determined for each whole number value of Kp from 0 to 5 and for Kp ≥ 6.