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首页> 外文期刊>Journal of Geophysical Research, A. Space Physics: JGR >The impact of sunlight on high-latitude equivalent currents
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The impact of sunlight on high-latitude equivalent currents

机译：阳光在高纬度地区的影响电流

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摘要

Ground magnetic field measurements can be mathematically related to an overhead ionospheric equivalent current. In this study we look in detail at how the global equivalent current, calculated using more than 30 years of SuperMAG magnetometer data, changes with sunlight conditions. The calculations are done using spherical harmonic analysis in quasi-dipole coordinates, a technique which leads to improved accuracy compared to previous studies. Sorting the data according to the location of the sunlight terminator and orientation of the interplanetary magnetic field (IMF), we find that the equivalent current resembles ionospheric convection patterns on the sunlit side of the terminator but not on the dark side. On the dark side, with southward IMF, the current is strongly dominated by a dawn cell and the current across the polar cap has a strong dawnward component. The contrast between the sunlit and dark side increases with increasing values of the F_(10.7) index, showing that increasing solar EUV flux changes not only the magnitude but also the morphology of the equivalent current system. The results are consistent with a recent study showing that Birkeland currents indirectly determine the equivalent current in darkness and that Hall currents dominate in sunlight. This has implication for the interpretation of ground magnetic field measurements and suggests that the magnetic disturbances at conjugate points will be asymmetrical when the solar illumination is different.
机译：地磁场测量电离层数学相关的开销等效电流。细节在全球等效电流,使用超过30年的SuperMAG计算磁强计数据,更改与阳光条件。在quasi-dipole球面调和分析坐标,导致技术改进准确性与先前的研究相比。数据的位置阳光的终结者和方向行星际磁场(IMF),我们发现相当于目前类似于电离层对流模式在阳光的一面终结者而不是黑暗的一面。向南与国际货币基金组织(IMF),当前的强烈由黎明细胞和当前的主导极冠有很强的dawnward组件。之间的对比阳光和阴暗的一面增加而增加的值f (10.7)指数显示,增加太阳能EUV通量变化不仅大小也形态学的等效电流系统。结果与最近的一项研究相一致间接表明Birkeland电流确定在黑暗和等效电流在阳光下,霍尔电流控制。含义的解释磁场测量和显示在共轭点磁干扰当太阳能照明是不对称的不同。

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