The Low Altitude Electric Field Structure of Discrete Auroral Arcs

2013 ◽  
pp. 136-142 ◽  
Author(s):  
F. S. Mozer
Keyword(s):  
Electric Field ◽  
Field Structure ◽  
Low Altitude ◽  
Auroral Arcs

scholarly journals The occurrence frequency of auroral potential structures and electric fields as a function of altitude using Polar/EFI data

2004 ◽  
Vol 22 (4) ◽  
pp. 1233-1250 ◽  
Author(s):  
P. Janhunen ◽  
A. Olsson ◽  
H. Laakso
Keyword(s):  
Electric Field ◽  
High Altitude ◽  
Electric Fields ◽  
Radial Distance ◽  
Plasma Potential ◽  
Potential Structure ◽  
New Finding ◽  
Low Altitude ◽  
Field Lines ◽  
Auroral Arcs

Abstract. The aim of the paper is to study how auroral potential structures close at high altitude. We analyse all electric field data collected by Polar on auroral field lines in 1996–2001 by integrating the electric field along the spacecraft orbit to obtain the plasma potential, from which we identify potential minima by an automatic method. From these we estimate the associated effective mapped-down electric field Ei, defined as the depth of the potential minimum divided by its half-width in the ionosphere. Notice that although we use the ionosphere as a reference altitude, the field Ei does not actually exist in the ionosphere but is just a convenient computational quantity. We obtain the statistical distribution of Ei as a function of altitude, magnetic local time (MLT), Kp index and the footpoint solar illumination condition. Surprisingly, we find two classes of electric field structures. The first class consists of the low-altitude potential structures that are presumably associated with inverted-V regions and discrete auroral arcs and their set of associated phenomena. We show that the first class exists only below ~3RE radial distance, and it occurs in all nightside MLT sectors (RE=Earth radius). The second class exists only above radial distance R=4RE and almost only in the midnight MLT sector, with a preference for high Kp values. Interestingly, in the middle altitudes (R=3–4RE) the number of potential minima is small, suggesting that the low and high altitude classes are not simple field-aligned extensions of each other. This is also underlined by the fact that statistically the high altitude structures seem to be substorm-related, while the low altitude structures seem to correspond to stable auroral arcs. The new finding of the existence of the two classes is important for theories of auroral acceleration, since it supports a closed potential structure model for stable arcs, while during substorms, different superposed processes take place that are associated with the disconnected high-altitude electric field structures. Key words. Magnetospheric physics (electric fields; auroral phenomena) – Space plasma physics (electrostatic structures)

Electric field structure in an active part of a small, isolated thundercloud

1981 ◽  
Vol 86 (C2) ◽  
pp. 1187 ◽  
Author(s):  
W. P. Winn ◽  
C. B. Moore ◽  
C. R. Holmes
Keyword(s):  
Electric Field ◽  
Field Structure ◽  
Active Part

Electric field structure optimization in IC solid state spatial light modulator

1992 ◽  
Author(s):  
Nickolay B. Kuleshov ◽  
Victor A. Tarasov ◽  
Igor V. Tokarev ◽  
Sergey S. Sarkisov
Keyword(s):  
Solid State ◽  
Electric Field ◽  
Spatial Light Modulator ◽  
Structure Optimization ◽  
Field Structure ◽  
Light Modulator

scholarly journals A statistical study of intense electric fields at 4−7 R<sub><i>E</i></sub> geocentric distance using Cluster

2005 ◽  
Vol 23 (7) ◽  
pp. 2579-2588 ◽  
Author(s):  
T. Johansson ◽  
T. Karlsson ◽  
G. Marklund ◽  
S. Figueiredo ◽  
P.-A. Lindqvist ◽  
...  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Time Distribution ◽  
Statistical Study ◽  
Auroral Oval ◽  
Field Structure ◽  
Geocentric Distance ◽  
Using Data ◽  
Auroral Phenomena ◽  
Current Systems

Abstract. Intense high-latitude electric fields (>150 mV/m mapped to ionospheric altitude) at 4–7 RE geocentric distance have been investigated in a statistical study, using data from the Cluster satellites. The orbit of the Cluster satellites limits the data collection at these altitudes to high latitudes, including the poleward part of the auroral oval. The occurrence and distribution of the selected events have been used to characterize the intense electric fields and to investigate their dependance on parameters such as MLT, CGLat, altitude, and also Kp. Peaks in the local time distribution are found in the evening to morning sectors but also in the noon sector, corresponding to cusp events. The electric field intensities decrease with increasing latitude in the region investigated (above 60 CGLat). A dependence on geomagnetic activity is indicated since the probability of finding an event increases up to Kp=5–6. The scales sizes are in the range up to 10 km (mapped to ionospheric altitude) with a maximum around 4–5km, consistent with earlier findings at lower altitudes and Cluster event studies. The magnitudes of the electric fields are inversely proportional to the scale sizes. The type of electric field structure (convergent or divergent) is consistent with the FAC direction for a subset of events with electric field intensities in the range 500–1000 mV/m and with clear bipolar signatures. The FAC directions are also consistent with the Region 1 and NBZ current systems, the latter of which prevail only during northward IMF conditions. For scale sizes less than 2 km the majority of the events were divergent electric field structures. Both converging and diverging electric fields were found throughout the investigated altitude range (4–7 RE geocentric distance). Keywords. Magnetospheric physics (Electric fields; Auroral phenomena; Magnetosphere-ionosphere interactions)

Anomalous Plasma Transport and Induced Electric Field in a Stochastic Magnetic Field Structure

1995 ◽  
Vol 27 (3T) ◽  
pp. 493-496 ◽  
Author(s):  
Tetsuyuki Kubota ◽  
Sanae -I. Itoh ◽  
Shinichiro Toda ◽  
Hiroki Yamaguchi ◽  
Atsushi Fukuyama
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Field Structure ◽  
Plasma Transport ◽  
Magnetic Field Structure ◽  
Stochastic Magnetic Field
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