Solar wind driving of dayside field-aligned currents

被引:18
作者
Wing, Simon [1 ]
Ohtani, Shin-ichi [1 ]
Johnson, Jay R. [4 ]
Echim, Marius [2 ,6 ]
Newell, Patrick T. [1 ]
Higuchi, Tomoyuki [3 ]
Ueno, Genta [3 ]
Wilson, Gordon R. [5 ]
机构
[1] Johns Hopkins Univ, Appl Phys Lab, Laurel, MD 20723 USA
[2] Inst Aeron Spatiale Belgique, B-1180 Brussels, Belgium
[3] Inst Stat Math, Dept Stat Modeling, Minato Ku, Tokyo 1068569, Japan
[4] Princeton Univ, Plasma Phys Lab, Princeton, NJ 08543 USA
[5] USAF, Res Lab, Albuquerque, NM 87111 USA
[6] Inst Space Sci, Bucharest, Romania
基金
美国国家科学基金会;
关键词
INTERPLANETARY MAGNETIC-FIELD; LATITUDE BOUNDARY-LAYER; DISCRETE AURORAL ARCS; BIRKELAND CURRENTS; PLASMA SHEET; LOW-ALTITUDE; ELECTRIC POTENTIALS; DYNAMIC PRESSURE; PARTICLE-PRECIPITATION; SOUTHWARD IMF;
D O I
10.1029/2011JA016579
中图分类号
P1 [天文学];
学科分类号
0704 ;
摘要
Variations in the dayside field-aligned current (FAC) density (J(//)), field-aligned parallel potential drop (Delta phi(//)), peak precipitating electron energy (peak E-e), and precipitating electron energy flux (epsilon) as functions of solar wind (SW) and interplanetary magnetic field (IMF) are investigated with Defense Meteorological Satellite Program observations and a quasi-stationary low-latitude boundary layer (LLBL)-FAC coupling model. Region 1 (R1) J(//) responses to variations in SW velocity (V-sw) and density (n(sw)) at 8-16 magnetic local time (MLT) suggest that R1 at these local times is frequently open while R1 at 6-08 and 17-18 MLT is frequently closed. R2 is located mostly on closed field lines. In the afternoon open R1 at 12-16 MLT, an increase in n(sw) increases J(//), decreases maximum peak Ee (proxy for Delta phi(//)), but has little effect on maximum epsilon. In the same R1 region, an increase in V-sw increases J(//), maximum peak E-e, and maximum epsilon. The dependencies of J(//), maximum peak E-e, and maximum epsilon are consistent with the Knight relation and the voltage generator at the magnetopause boundary in the afternoon open R1. In the midmorning and midafternoon, the response of J(//) to V-sw is higher for southward than for northward IMF. This can be attributed to the higher-velocity shear at the magnetopause boundary due to higher sunward convection in the LLBL inside the magnetopause. R1 in the closed-field lines near dawn and dusk appears to be more sensitive to merging rate (d Phi/dt = V-4/3(sw) B-T(2/3) sin(8/3)(theta(c)/2)) than to SW dynamic pressure.
引用
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页数:17
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