Strong disturbance of the upper thermospheric density due to magnetic storms: CHAMP observations
Strong disturbance of the upper thermospheric density due to magnetic storms: CHAMP observations
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DOI：
10.1029/2004ja010908
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发表时间：
2005-09
影响因子：
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通讯作者：
Huixin Liu;H. Lühr
中科院分区：
文献类型：
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作者：
Huixin Liu;H. Lühr
[1]在2003年10月29日至30日、2003年10月30日至31日和2003年11月20日至22日发生的三次地磁超级风暴期间，CHAMP卫星在大约400公里高度观测到上部热层总质量密度的强烈增强。相应的密度增强在中午和午夜扇区的安静时间值的400%，500%和800%左右达到峰值。扰动表现出强烈的中午-午夜和半球/季节的不对称性。在中午区域，夏季南半球的平均密度增强比冬季北方强。然而，在午夜时段，关于季节性影响还不能得出普遍的结论。较强的密度增强发生在夏季半球的第二次和第三次风暴事件，而在冬季半球的第一次风暴事件。昼夜之间扰动的相对强度很大程度上取决于我们对强度的定义。当以绝对值（风暴平静）表示时，在所有三场风暴中，夜间的密度增强通常不到白天的一半。然而，当以百分比（）表示时，夜间的增强与白天相当，甚至更大。在11月风暴期间，扰动从高纬度向低纬度的传播在夏季（南半球）比在冬季（北方）半球的昼侧和夜侧都要快。在冬季半球，在白天的传播被发现是快于在夜侧。这些季节/半球不对称性随当地时间和个别事件的变化意味着，磁暴中涉及的许多不同的竞争过程也可能随当地时间和事件而发生显着变化。MSIS 90模式无法重现这三个风暴的大部分观测特征。
[1] Strong enhancements of the upper thermospheric total mass density were observed by the CHAMP satellite at approximately 400 km altitude during three geomagnetic superstorms occurring on 29–30 October 2003, 30–31 October 2003, and 20–22 November 2003. The corresponding density enhancements peaked around 400%, 500%, and 800% of the quiet-time values in both noon and midnight sectors. The disturbances showed strong noon–midnight and hemispheric/seasonal asymmetry. In the noon sector, the average density enhancement was stronger in summer (southern) than in the winter (northern) hemisphere. In the midnight sector, however, no general conclusion can be drawn about the seasonal effect. Stronger density enhancements occurred in the summer hemisphere during the second and third storm events, while in the winter hemisphere during the first storm event. The relative intensity of the disturbance between day and night is strongly dependent on our definition of the intensity. When expressed in absolute terms (storm-quiet), the density enhancement at night was generally less than half of that at day during all three storms. When expressed in percentage terms (), however, the enhancement at night was comparable to or even larger than that at day. The propagation of the disturbance from high to low latitudes during the November storm was faster in summer (southern) than in the winter (northern) hemisphere on both dayside and nightside. In the winter hemisphere, the propagation on the dayside was found to be faster than on the nightside. These variations of the seasonal/hemispheric asymmetry with local time and individual event imply that the many different competing processes involved in a magnetic storm may also vary dramatically with local time and from event to event. The MSIS90 model was unable to reproduce most of the observed features of these three storms.