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首页> 外文期刊>Journal of Geophysical Research. Biogeosciences >Effects of magnetospheric precipitation and ionospheric conductivity on the ground magnetic signatures of traveling convection vortices
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Effects of magnetospheric precipitation and ionospheric conductivity on the ground magnetic signatures of traveling convection vortices

机译：磁层降水和电离层电导率对移动对流涡旋的地面磁信号的影响

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By using an improved TCV model (Zhu et al., 1997), a quantitative study of the effects of magnetospheric precipitation and ionospheric background conductivity on the ground magnetic signatures of traveling convection vortices (TCVs) has been conducted. In this study the localized conductivity enhancement associated with the TCVs is present and the ratio of the Hall and Pedersen conductances vary both spatially and temporally according to the hardness of the TCV precipitation. It is found that a strong conductivity enhancement associated with hard TCV precipitation can significantly distort the TCV current closure in the ionosphere and lead to ground magnetic disturbance patterns with strong asymmetry in E-W direction. The asymmetry of the ground magnetic patterns is characterized by a stronger magnetic disturbance on the side of the upward field-aligned currents (clockwise convection cell) and a possible rotation of the whole magnetic patterns. Specifically, the modeling results predict that when the characteristic energy of the TCV precipitation is below 500 eV, the asymmetry of the ground magnetic patterns is minimal (less than 1%) and may not be detectable. When the characteristic energy of the precipitation is about 7 keV, the asymmetry of the magnetic patterns can be well above 30%. It is also found that a low ionospheric background conductivity favors the appearance of strong asymmetry in the ground magnetic patterns of the TCVs, while a high ionospheric background conductivity favors the appearance of strong ground magnetic disturbances but with less asymmetry. We concluded that the most favorable condition for the appearance of strong asymmetry in the TCV ground magnetic signatures is the condition of winter, solar minimum, and hard precipitation.
机译：通过使用改进的TCV模型（Zhu等，1997），进行了磁层降水和电离层背景电导率对移动对流涡流（TCVs）地面磁信号影响的定量研究。在这项研究中，存在与TCV相关的局部电导率增强，并且霍尔和Pedersen电导的比值根据TCV沉淀的硬度在空间和时间上都发生变化。发现与硬TCV沉淀有关的强电导率增强会显着扭曲电离层中TCV电流的闭合，并导致在E-W方向上具有强烈不对称性的地面磁干扰模式。接地磁模式的不对称性的特征在于，在向上的磁场对准电流（顺时针对流单元）一侧的磁场干扰更大，整个磁模式可能旋转。具体而言，建模结果预测，当TCV沉淀的特征能量低于500 eV时，接地磁模式的不对称性极小（小于1％），并且可能无法检测到。当沉淀的特征能量为约7keV时，磁性图案的不对称性可以远高于30％。还发现电离层本底电导率低有利于TCV的接地磁模式出现强不对称性，而电离层本底电导率较高有利于强地磁干扰的出现，但不对称性较小。我们得出的结论是，TCV地磁特征中出现强不对称性的最有利条件是冬季，最低日照和强降水条件。

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