Surveys of 557.7/630.0 nm Dayside Auroral Emissions in Ny-Ålesund, Svalbard, and South Pole Station
Surveys of 557.7/630.0 nm Dayside Auroral Emissions in Ny-Ålesund, Svalbard, and South Pole Station
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DOI：
10.1002/9781119216346.ch11
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发表时间：
2017-10
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影响因子：
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通讯作者：
Zejun Hu;Huigen Yang;Y. Ebihara;Hongqiao Hu;Beichen Zhang
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作者：
Zejun Hu;Huigen Yang;Y. Ebihara;Hongqiao Hu;Beichen Zhang
分别从北极黄河站和南极南极站的全天空成像仪获取的北方半球和南半球昼侧极光的天气分布呈现相同的双峰结构，即中午09：00 MLT和中午14：00-15：00 MLT峰值。极光强度呈现半球不对称性，即南半球午后强度小于午后强度，而北方半球午后强度大于午后强度。虽然（1）在不同的极性下，大脑半球的不对称性并不随IMF极性的改变而改变，（正）IMFBy有利于午后557.7/630.0 nm极光发射，（负）By有利于北方正午前卵圆上630.0 nm极光的激发（2）在负IMFBz期间，日侧椭圆区630.0nm极光强度显著增强。我们认为：（1）昼侧椭圆的双峰结构主要与高纬磁层顶中午前后的反平行重联作用有关，中午前后的峰值产生于高纬磁层顶;（2）IMFBy通过南北向电场产生的半球间电流，改变中午R 0-R1电流的分布，调制昼侧极光;（3）两半球昼侧极光分布的前后不对称性是磁鞘密度的前后变化和两个地面观测站的局地电离层电导率变化共同作用的结果。
The synoptic distribution of dayside aurora in the Northern and Southern Hemispheres, acquired from all‐sky imagers at Yellow River Station in the Arctic and South Pole Station in Antarctica, respectively, presents the same two‐peak structure, namely, the prenoon 09:00 MLT and postnoon 14:00–15:00 MLT peaks. The auroral intensity presents a hemispheric asymmetry, that is, the postnoon intensity is less than the prenoon intensity in the Southern Hemisphere but more in the Northern Hemisphere. The hemispheric asymmetry is not changed with the change of IMF's polarity, although (1) the negative (positive) IMFByfavors the postnoon 557.7/630.0 nm auroral emissions, and the positive (negative)Byfavors the excitation of 630.0 nm auroral on prenoon oval in the Northern (Southern) Hemisphere; (2) the 630.0 nm auroral intensity in dayside oval increases dramatically during the negative IMFBz. We suggest that (1) the two‐peak structure in the dayside oval is predominantly related with the prenoon/postnoon antiparallel reconnection in high‐latitude magnetopause produced to the prenoon and postnoon peaks; (2) the IMFByshould modulate the dayside aurora through the interhemispheric current, which is produced by a north‐south oriented electric field, and changing the distribution of middayR0‐R1 current; (3) the opposite prenoon‐postnoon asymmetries of dayside auroral distribution in the two hemispheres are the combined effect of the prenoon‐postnoon variations of the magnetosheath density and the variation of the local ionospheric conductivity in the two ground‐based observatories.