Field‐aligned currents associated with dipolarization fronts. Issue 17 (6th September 2013)

• Record Type: Journal Article
• Authors: Sun, W. J.; Fu, S. Y.; Parks, G. K.; Liu, J.; Yao, Z. H.; Shi, Q. Q.; Zong, Q.‐G.; Huang, S. Y.; Pu, Z. Y.; Xiao, T.
• Is Part Of: Geophysical research letters. Volume 40:Issue 17(2013:Sep.)
• Page Start: 4503
• Page End: 4508
• Publication Date: 2013-09-06
• Subjects: Geophysics -- Periodicals; Planets -- Periodicals; Lunar geology -- Periodicals; 550
• DOI: 10.1002/grl.50902
• Languages: English
• ISSNs: 0094-8276

Abstract

<abstract abstract-type="main" id="grl50902-abs-0001"> <title> <x xml:space="preserve">Abstract</x> </title> <p id="grl50902-para-0001">[1] Current densities associated with dipolarization fronts (DFs) have been calculated in the geomagnetic tail using the curlometer technique applied to high‐resolution magnetic field <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg3jz5qvt7" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="block" altimg="urn:x-wiley:grl:media:grl50902:grl50902-math-0001" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:math></alternatives> data obtained by the four Cluster spacecraft. We then use the relation <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg3jz5qvqk" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="block" altimg="urn:x-wiley:grl:media:grl50902:grl50902-math-0002" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mfenced open="〈" close="〉"><mml:mrow><mml:mover accent="true"><mml:mrow><mml:mi>b</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:mrow></mml:mfenced><mml:mo>·</mml:mo><mml:mfenced open="(" close=")"><mml:mrow><mml:mo>∇</mml:mo><mml:mo>×</mml:mo><mml:mover accent="true"><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:mrow></mml:mfenced></mml:math></alternatives> to characterize the behavior of field‐aligned current (FAC) during 25 DF events. Our results show that the magnitude of FAC density (<italic>J</italic><sub>//</sub>) ranges from 5 to 20 nA/m<sup>2</sup>, and they are observed in Northern and Southern Hemispheres flowing along both directions of the <alternatives><inline-graphic mimetype="image" xlink:href="ark:/27927/pgg3jz5qvng" xlink:type="simple" xmlns:xlink="http://www.w3.org/1999/xlink" /><mml:math display="block" altimg="urn:x-wiley:grl:media:grl50902:grl50902-math-0003" overflow="scroll" xmlns:mml="http://www.w3.org/1998/Math/MathML"><mml:mover accent="true"><mml:mrow><mml:mi>B</mml:mi></mml:mrow><mml:mo>→</mml:mo></mml:mover></mml:math></alternatives>‐field. The FACs have dimensions characteristic of the DFs and with region‐1 current sense flowing inside the DFs and region‐2 sense just in front of DF (in the <italic>B</italic><sub><italic>z</italic></sub> dips). Most of our observations come from 15 to 20 <italic>R</italic><sub><italic>E</italic></sub> in the tail, different from previous statistical studies based mainly on observations made around 9–12 <italic>R</italic><sub><italic>E</italic></sub>. We suggest that DFs can sustain significant FACs and appear as "wedgelets" in the early stage.</p> </abstract>