Statistics of the field‐aligned currents at the high‐latitude energetic electron boundaries in the nightside: Cluster observation

Ren, Jie; Zong, Qiugang; Zhou, Xinzhu; Zhang, Hui; Fu, S. Y.; Wang, Y. F.; Liu, Yong C.‐M.

doi:10.1002/2015ja021754

Cited by 4 publications

(6 citation statements)

References 56 publications

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“…But the IMF ( B ) variation always positively correlated with FAC for any kind of geomagnetic activity. This result is in accordance with Ren et al () that the FACs and the corresponding magnetic field variation ( B ) are positively correlated with the global level of the geomagnetic activity and almost independent of the substorm activity. In all geomagnetic event, the FAC varies SYM‐H with good negative correlation except supersubstorm event. The FAC‐ SYM ( H ) correlation depends upon the strength of the geomagnetic disturbance.…”

Section: Resultssupporting

confidence: 93%

“…But the IMF ( B ) variation is positively correlated with FAC for any kind of geomagnetic activity. This result is in accordance with Ren et al () that the FACs and the corresponding magnetic field variation ( B ) are positively correlated with the global level of the geomagnetic activity and almost independent of the substorm activity. The Earth's dipole interacts with the magnetic field possessed by the solar wind that is interplanetary magnetic field (IMF) and this results in increased energy being transferred to the magnetosphere (Dungey, ).…”

Section: Cross Correlationsupporting

confidence: 93%

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Field‐Aligned Current and Polar Cap Potential and Geomagnetic Disturbances: A Review of Cross‐Correlation Analysis

Adhikari

Dahal²,

Sapkota³

et al. 2018

Earth and Space Science

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Polar cap potential (PCV) is an important parameter used for determining what kind of interaction takes place between solar wind and magnetosphere. Highly energetic particles from Sun driven by solar wind constantly bombard with Earth's magnetosphere–ionosphere system that results into a phenomenon like auroras, and major geomagnetic disturbances. Solar wind electron deposition determines the magnitude of field‐aligned current (FAC) and ultimately leads to PCV variation. Several studies found that increase in magnitude of IMF‐Bz causes an electric field of cross magnetosphere to increase, and it leads to increase in magnitude of ionospheric cross‐polar cap potential (PCV). Moreover, PCV was found to be a linear function of Vsw. In this research, we aim to study how field‐aligned current (FAC), for example, region 1 current and PCV, is related during different forms of geomagnetic disturbances. In all events, FAC and PCV are found to have corresponding fluctuations—especially at times of significant variation of IMF‐Bz (negative Bz interval) following the linearity of equation suggested by Moon in Moon (2012, https://doi.org/10.5140/JASS.2012.29.3.259). We found one‐to‐one correspondence between FAC and PCV. We did CWT analysis and found that FAC and PCV have more or less same spectral behaviors for each event considered. The cross‐correlation analysis shows a high and positive correlation between FAC and PCV at 0‐min time lag for all geomagnetic activity. The CWT analysis clearly supports the result of cross correlation between FAC and PCV. We found that FAC and Vsw, FAC‐B, and FAC and AE are also positively correlated with high‐correlation coefficient at lag 0 min for all geomagnetic storm. However, FAC‐Bz, FAC‐By, and FAC‐SYM (H) have varying correlation in different events. For a particular storm and substorm, the parameters Bz and By may not necessarily be varied with FAC in regular sequence but IMF (B) always show positive correlation with FAC for all geomagnetic activity. This paper presents a clear relation between FAC and PCV. This result will help to identify some of the outstanding issues in determining the causal mechanism of PCV variation, a crucial thing to understanding the coupling between the solar wind and M‐I system.

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Section: Resultssupporting

confidence: 93%

Section: Cross Correlationsupporting

confidence: 93%

Field‐Aligned Current and Polar Cap Potential and Geomagnetic Disturbances: A Review of Cross‐Correlation Analysis

Adhikari

Dahal²,

Sapkota³

et al. 2018

Earth and Space Science

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“…4, each event occurred when the AE index was 78 and 106 nT and the Kp index was 1-2. It is comparable with the work by Ren et al (2016), in which the relations between J (∆B) and the indices (AE and Kp) were determined using the linear fits in the same region as in this study. The relations are ( 1 We examined how reliable the current estimation is in terms of some parameters.…”

Section: Discussionsupporting

confidence: 90%

“…However, it is mapped to the invariant latitude lower than that reported by Ijima & Potemra (1976a), in which the R1 currents are located at the invariant latitudes between 70° and 75° in the northern hemisphere during a quiet time. In addition, Ren et al (2016) reported using statistical analysis that in the same region as in this study, current density is tens of nA/m 2 , the thickness is hundreds of kilometers, and the distribution of FACs in magnetic latitude mapped to the ionosphere coincides with the auroral zone. These results are well consistent with our results.…”

Section: Discussionsupporting

confidence: 57%

Analysis of Field-Aligned Currents in the High-Altitude Nightside Auroral Region: Cluster Observation

Yourashin¹,

Lee²,

Lee³

2019

Journal of Astronomy and Space Sciences

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In this paper we present analysis of current density when the Cluster spacecraft pass the nightside auroral region at about 4-5 RE from the center of Earth. The analysis is made when the inter-spacecraft separation is within 200 km, which allows all four spacecraft to be situated inside the same current sheet. On 22 February 2002, two field-aligned current (FAC) events were observed in both the southern and the northern hemispheres. The FACs were calculated with magnetic field data obtained by the four spacecraft using the Curlometer method. The scales of the FACs along the spacecraft trajectory and the magnitudes were hundreds of kilometers and tens of nA/m2, respectively, and both events were mapped to the auroral region in the ionosphere. We also examined reliability of the results with some parameters, and found that our results are adequately comparable with other studies. Nevertheless, some limitations that decrease the accuracy of current estimation exist.

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“…They appear to be generated on open field lines, or perhaps more correctly, they are diverted from perpendicular currents flowing across open field lines there. This feature is consistent with recent Cluster satellite observations [Ren et al, 2016]. The reversed field-aligned currents at the edges of plasma sheet fast flow channels in the equatorial cut of Figure 6 are also evident in the y-z cuts of Figure 7.…”

Section: Magnetosphere-ionosphere Couplingsupporting

confidence: 91%

Effects of auroral potential drops on plasma sheet dynamics

Lotko

Zhang

et al. 2016

JGR Space Physics

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The reaction of the magnetosphere‐ionosphere system to dynamic auroral potential drops is investigated using the Lyon‐Fedder‐Mobarry global model including, for the first time in a global simulation, the dissipative load of field‐aligned potential drops in the low‐altitude boundary condition. This extra load reduces the field‐aligned current (j||) supplied by nightside reconnection dynamos. The system adapts by forcing the nightside X line closer to Earth, with a corresponding reduction in current lensing (j||/B = constant) at the ionosphere and additional contraction of the plasma sheet during substorm recovery and steady magnetospheric convection. For steady and moderate solar wind driving and with constant ionospheric conductance, the cross polar cap potential and hemispheric field‐aligned current are lower by approximately the ratio of the peak field‐aligned potential drop to the cross polar cap potential (10–15%) when potential drops are included. Hemispheric ionospheric Joule dissipation is less by 8%, while the area‐integrated, average work done on the fluid by the reconnecting magnetotail field increases by 50% within |y| < 8 RE. Effects on the nightside plasma sheet include (1) an average X line 4 RE closer to Earth; (2) a 12% higher mean reconnection rate; and (3) dawn‐dusk asymmetry in reconnection with a 17% higher rate in the premidnight sector.

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Statistics of the field‐aligned currents at the high‐latitude energetic electron boundaries in the nightside: Cluster observation

Cited by 4 publications

References 56 publications

Field‐Aligned Current and Polar Cap Potential and Geomagnetic Disturbances: A Review of Cross‐Correlation Analysis

Field‐Aligned Current and Polar Cap Potential and Geomagnetic Disturbances: A Review of Cross‐Correlation Analysis

Analysis of Field-Aligned Currents in the High-Altitude Nightside Auroral Region: Cluster Observation

Effects of auroral potential drops on plasma sheet dynamics

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