The polar ionosphere at Zhongshan station on May 11, 1999, the day the solar wind almost disappeared
The polar ionosphere at Zhongshan station on May 11, 1999, the day the solar wind almost disappeared
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DOI：
10.1007/bf02889698
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发表时间：
2002
期刊：
影响因子：
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通讯作者：
Hongqiao Hu;Rui-yuan Liu;Yonghua Liu;Huigen Yang;Shunlin Liu;Beichen Zhang;Yong Ai;N. Sato;B. J. Fraser
中科院分区：
文献类型：
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作者：
Hongqiao Hu;Rui-yuan Liu;Yonghua Liu;Huigen Yang;Shunlin Liu;Beichen Zhang;Yong Ai;N. Sato;B. J. Fraser
1999年5月11日太阳风几乎消失：太阳风等离子体密度和动压分别小于1cm-3和0.1 nPa，行星际磁场偏北。利用南极中山站多台仪器在事件日和对照日（5月14日）观测到的极区电离层资料进行了比较。结果表明，5月11日中山地磁活动平静。磁脉动通常发生在磁午左右，没有出现。电离层是稳定的、分层的，F2层扩散很小。日侧F2层的临界频率f0 F2比对照日大，峰值提前2 h出现。电离层漂移速度小于正常值。磁中午出现强烈的极光。这些都表明，5月11日极区电离层异常平静，地磁场更呈偶极性。午夜前的极光亚暴特征有地磁H分量负偏差、极光Es和弱Pc 3脉动等。
The solar wind almost disappeared on May 11, 1999: the solar wind plasma density and dynamic pressure were less than 1cm−3and 0.1 nPa respectively, while the interplanetary magnetic field was northward. The polar ionospheric data observed by the multi-instruments at Zhongshan Station in Antarctica on such special event day was compared with those of the control day (May 14). It was shown that geomagnetic activity was very quiet on May 11 at Zhongshan. The magnetic pulsation, which usually occurred at about magnetic noon, did not appear. The ionosphere was steady and stratified, and the F2layer spread very little. The critical frequency of day-side F2layer, f0F2, was larger than that of control day, and the peak of f0F2appeared 2 hours earlier. The ionospheric drift velocity was less than usual. There were intensive auroral Esappearing at magnetic noon. All this indicates that the polar ionosphere was extremely quiet and geomagnetic field was much more dipolar on May 11. There were some signatures of auroral substorm before midnight, such as the negative deviation of the geomagnetic H component, accompanied with auroral Esand weak Pc3 pulsation.