scholarly journals Comparisons between ion distributions retrieved from ENA images of the ring current and contemporaneous, multipoint ion measurements recorded in situ during the major magnetic storm of 15 May 2005

2010 ◽  
Vol 115 (A12) ◽  
pp. n/a-n/a ◽  
Author(s):  
L. Lu ◽  
S. McKenna-Lawlor ◽  
S. Barabash ◽  
P. C. Brandt ◽  
J. Balaz ◽  
...  
Keyword(s):  
Magnetic Storm ◽  
Ring Current ◽  
Ion Distributions

Magnetic storm of September 4, 1984: A synthesis of ring current spectra and energy densities measured with AMPTE/CCE

1985 ◽  
Vol 12 (5) ◽  
pp. 329-332 ◽  
Author(s):  
S. M. Krimigis ◽  
G. Gloeckler ◽  
R. W. McEntire ◽  
T. A. Potemra ◽  
F. L. Scarf ◽  
...  
Keyword(s):  
Magnetic Storm ◽  
Ring Current

scholarly journals New Developments in Scanning Microelectrochemical Techniques: A Highly Sensitive Route to Evaluate Degradation Reactions and Protection Methods with Chemical Selectivity

2018 ◽  
Vol 875 ◽  
pp. 19-23
Author(s):  
Ricardo M. Souto ◽  
Dániel Filotás ◽  
Bibiana M. Fernández-Pérez ◽  
Lívia Nagy ◽  
Géza Nagy
Keyword(s):  
Galvanized Steel ◽  
New Developments ◽  
Saline Environment ◽  
Spatially Resolved ◽  
Degradation Reactions ◽  
Ion Distributions ◽  
Scanning Electrochemical Microscope ◽  
Highly Sensitive ◽  
Chemical Selectivity

The scanning electrochemical microscope (SECM) offers a highly sensitive route to evaluate degradation reactions and protection methods with chemical selectivity by using ion-selective microelectrodes as tips, thus operating SECM potentiometrically. Spatially resolved imaging of electrochemical reactivity related to each component of the investigated material can thus be effectively monitored selectively both in situ and in real time. The applicability of this method has been illustrated using a practical example of a metal-coating system, consisting in the exposure of cut edges of coil-coated galvanized steel to aqueous saline environment. In this contribution, localized pH and zinc(II) ion distributions originated around cut edges of coil coated steel immersed in 1 mM NaCl solution are shown.

scholarly journals The distribution of the ring current: Cluster observations

2011 ◽  
Vol 29 (9) ◽  
pp. 1655-1662 ◽  
Author(s):  
Q.-H. Zhang ◽  
M. W. Dunlop ◽  
M. Lockwood ◽  
R. Holme ◽  
Y. Kamide ◽  
...  
Keyword(s):  
Current Density ◽  
Ring Current ◽  
Local Times ◽  
Distribution Profile ◽  
Full Circle ◽  
Equatorial Current ◽  
The Mean ◽  
Current Flows ◽  
First Time

Abstract. Extending previous studies, a full-circle investigation of the ring current has been made using Cluster 4-spacecraft observations near perigee, at times when the Cluster array had relatively small separations and nearly regular tetrahedral configurations, and when the Dst index was greater than −30 nT (non-storm conditions). These observations result in direct estimations of the near equatorial current density at all magnetic local times (MLT) for the first time and with sufficient accuracy, for the following observations. The results confirm that the ring current flows westward and show that the in situ average measured current density (sampled in the radial range accessed by Cluster ~4–4.5 RE) is asymmetric in MLT, ranging from 9 to 27 nA m−2. The direction of current is shown to be very well ordered for the whole range of MLT. Both of these results are in line with previous studies on partial ring extent. The magnitude of the current density, however, reveals a distinct asymmetry: growing from 10 to 27 nA m−2 as azimuth reduces from about 12:00 MLT to 03:00 and falling from 20 to 10 nA m−2 less steadily as azimuth reduces from 24:00 to 12:00 MLT. This result has not been reported before and we suggest it could reflect a number of effects. Firstly, we argue it is consistent with the operation of region-2 field aligned-currents (FACs), which are expected to flow upward into the ring current around 09:00 MLT and downward out of the ring current around 14:00 MLT. Secondly, we note that it is also consistent with a possible asymmetry in the radial distribution profile of current density (resulting in higher peak at ~4–4.5 RE). We note that part of the enhanced current could reflect an increase in the mean AE activity (during the periods in which Cluster samples those MLT).

scholarly journals <i>Swarm</i> field-aligned currents during a severe magnetic storm of September 2017

2019 ◽  
Author(s):  
Renata Lukianova
Keyword(s):  
Magnetic Storm ◽  
Ring Current ◽  
Current System ◽  
Small Scale ◽  
Substantial Fraction ◽  
H Index ◽  
Swarm Satellites ◽  
Scale Field ◽  
Extreme Behavior ◽  
A Current

Abstract. Swarm satellites observations are used to characterize the extreme behavior of large- and small-scale field-aligned currents (FACs) during the severe magnetic storm of September 2017. Evolution of the current intensities and the equatorward displacement of FACs are analyzed while the satellites cross the pre-midnight, pre-noon, dusk and dawn sectors in both hemispheres. The equatorward boundaries of FACs mainly follow the dynamics of ring current (as monitored in terms of the SYM-H index). The minimum latitude of the FAC boundaries is limited to 50° MLat, below which saturation occurs. The FAC densities are very variable and may increase dramatically, especially in the nightside ionosphere during the storm-time substorms. At the peak of substorm, the average FAC densities reach 3 μA/m2, while the quite level is below 0.1 μA/m2. The dawn–dusk asymmetry is manifested in the enhanced dusk-side R2 FACs in both hemispheres. Filamentary high-density structures are always observed confirming that a substantial fraction of R1/R2 FACs is composed of many small-scale currents. In the pre-noon sector, the bipolar structures (7.5 km width FACs of opposite polarities adjacent to each other) dominate, while in the post-midnight sector the upward and downward FACs tend to form more latitudinally extended structures of a certain polarity. The most intense small-scale FACs (up to ~80 μA/m2) is observed just in the post-midnight sector. Simultaneous magnetic and plasma perturbations indicate that this structure is likely a current system of a mesoscale auroral arc.

scholarly journals Ion distributions upstream and downstream of the Earth's bow shock: first results from Vlasiator

2013 ◽  
Vol 31 (12) ◽  
pp. 2207-2212 ◽  
Author(s):  
D. Pokhotelov ◽  
S. von Alfthan ◽  
Y. Kempf ◽  
R. Vainio ◽  
H. E. J. Koskinen ◽  
...  
Keyword(s):  
Distribution Functions ◽  
Bow Shock ◽  
Three Dimensions ◽  
Ion Distribution ◽  
Plasma Kinetics ◽  
Ion Distributions ◽  
Spatial Dimensions ◽  
First Results ◽  
Earth’S Bow Shock

Abstract. A novel hybrid-Vlasov code, Vlasiator, is developed for global simulations of magnetospheric plasma kinetics. The code is applied to model the collisionless bow shock on scales of the Earth's magnetosphere in two spatial dimensions and three dimensions in velocity space retrieving ion distribution functions over the entire foreshock and magnetosheath regions with unprecedented detail. The hybrid-Vlasov approach produces noise-free uniformly discretized ion distribution functions comparable to those measured in situ by spacecraft. Vlasiator can reproduce features of the ion foreshock and magnetosheath well known from spacecraft observations, such as compressional magnetosonic waves generated by backstreaming ion populations in the foreshock and mirror modes in the magnetosheath. An overview of ion distributions from various regions of the bow shock is presented, demonstrating the great opportunities for comparison with multi-spacecraft observations.

Multi-Step Dst Development and Ring Current Composition Changes During the 4-6 Jun 1991 Magnetic Storm

2001 ◽  
Author(s):  
J. U. Kozyra ◽  
M. W. Liemohn ◽  
C. R. Clauer ◽  
J. Ridley ◽  
M. F. Thomsen
Keyword(s):  
Magnetic Storm ◽  
Ring Current ◽  
Composition Changes

The MLT distribution and detailed structure of ring current:  MMS observations

2021 ◽  
Author(s):  
Xin Tan ◽  
Malcolm Dunlop ◽  
Xiangcheng Dong ◽  
Yanyan Yang ◽  
Christopher Russell
Keyword(s):  
Current Density ◽  
Large Scale ◽  
Ring Current ◽  
Current System ◽  
Radial Profile ◽  
Three Dimensional ◽  
Current Density Distribution ◽  
Magnetic Storms ◽  
In Situ Data

&lt;p&gt;The ring current is an important part of the large-scale magnetosphere-ionosphere current system; mainly concentrated in the equatorial plane, between 2-7 R&lt;sub&gt;E&lt;/sub&gt;, and strongly ordered between &amp;#177; 30 &amp;#176; latitude. The morphology of ring current directly affects the geomagnetic field at low to middle latitudes. Rapid changes in ring current densities can occur during magnetic storms/sub-storms. Traditionally, the Dst index is used to characterize the intensity of magnetic storms and to reflect the variation of ring current intensity, but this index does not reflect the MLT distribution of ring current. In fact, the ring current has significant variations with MLT, depending on geomagnetic activity, due to the influence of multiple factors; such as, the partial ring current, region 1/region 2 field-aligned currents, the magnetopause current and sub-storm cycle (magnetotail current). The form of the ring current has been inferred from the three-dimensional distribution of ion differential fluxes from neutral atom imaging; however, this technique can not directly obtain the current density distribution (as can be obtained using multi-spacecraft in situ data). Previous in situ estimates of current density have used: Cluster, THEMIS and other spacecraft groups to study the distribution of the ring current for limited ranges of either radial profile, or MLT and MLAT variations. Here, we report on an extension to these studies using FGM data from MMS obtained during the period September 1, 2015 to December 31, 2016, when the MMS orbit and configuration provided good coverage. We employ the curlometer method to calculate the current density, statistically, to analysis the MLT distribution according to different geomagnetic conditions. Our results show the clear asymmetry of the ring current and its different characteristics under different geomagnetic conditions.&lt;/p&gt;

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