Influence of ionosphere conductivity on the ring current
Influence of ionosphere conductivity on the ring current
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DOI：
10.1029/2003ja010351
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发表时间：
2004-05
影响因子：
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通讯作者：
Y. Ebihara;M. Fok;R. Wolf;T. Immel;T. Moore
中科院分区：
文献类型：
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作者：
Y. Ebihara;M. Fok;R. Wolf;T. Immel;T. Moore
[1]利用自洽求解环电流质子运动方程和磁层与电离层之间电流闭合的综合环电流模型(CRCM)，研究了电离层电导率的不同变化对环电流强度的影响。当F10.7=250×104Janskys(Jy)(太阳最大值条件)时，产生的环电流比F10.7=70×104Jy(太阳最小值条件)时大29%。春分时的电导率比冬至时大5%，这是因为春分时的两个半球的高度积分电导率比冬至时高。这将是一种解释DST半年变化的新机制。用磁层顶至极光全球探测成像仪(IMAGE)/远紫外线成像仪(FUV)极光成像仪数据估计的真实极光电导率进行模拟，结果表明，极光增亮并不显著改变环电流的强度。当极光电导率在DST最小值附近突然下降，触发环电流的快速衰减时，就会产生过屏蔽条件。环电流不仅受行星际磁场和太阳风的影响，而且还受太阳辐射和极光电子降水的形态特征的影响。
[1] Using the Comprehensive Ring Current Model (CRCM), which self-consistently solves the kinetic equation of ring current protons and the closure of the electric current between the magnetosphere and ionosphere, we have studied how different changes in the ionospheric conductivity affect the strength of the ring current. The conductivity for F10.7 = 250 × 104 Janskys (Jy) (solar maximum condition) results in a ring current that is about 29% stronger than for F10.7 = 70 × 104 Jy (solar minimum condition). The conductivity at equinox results in a ring current that is about 5% stronger than at solstice because the two-hemisphere height-integrated conductivities at equinox are higher than at solstice. This would be a new mechanism for explaining the semiannual variation of Dst. Simulation with a realistic auroral conductivity estimated from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE)/Far Ultraviolet Imager (FUV) auroral imager data reveals the fact that auroral brightenings do not significantly change the intensity of the ring current. The overshielding condition is found to be produced when the auroral conductivity decreases abruptly near the Dst minimum, triggering a rapid decay of the ring current. The ring current is shown to be influenced not only by the interplanetary magnetic field and the solar wind but also by solar radiation and morphological features of the auroral electron precipitation as well.