Unusually quick development of a 4000 nT substorm during the initial 10 min of the 29 October 2003 magnetic storm
Unusually quick development of a 4000 nT substorm during the initial 10 min of the 29 October 2003 magnetic storm
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DOI：
10.1029/2005ja011285
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发表时间：
2006-04
影响因子：
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通讯作者：
M. Yamauchi;T. Iyemori;H. Frey;M. Henderson
中科院分区：
文献类型：
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作者：
M. Yamauchi;T. Iyemori;H. Frey;M. Henderson
[1]全球地磁场数据，IMAGE FUV数据，和许多其他的现场观测，为最初的10分钟的磁暴开始于2003年10月29日0610 UT左右。在突然开始（SC）后的1 min内，磁层内区两个独立的强向西电离层电急流（>2000 nT）同时开始，一个在晚上-午夜扇区，另一个在早晨扇区。这两种活动都扩大了，并伴随着极光的扩张。这两种活动的位置（内磁层）、形态（膨胀）和强度（>2000 nT）都属于亚暴膨胀阶段。具有这种同时独立的2000 nT水平扩展使得该事件独一无二。SC之前的行星际磁场条件不利于导致AL < −2000 nT的活动。时间分析表明，这些强烈的向西电射流很可能是由行星际激波触发的，触发位置不超过地球同步距离。它们也可能是由太阳风的直接能量泵送维持的，因为在此期间，来自位置接近的GOES-10和Polar的交叉尾电流并没有减少很多。一个局部的，但更强的地磁（近4000 nT）和极光活动开始后，只有6分钟的SC开始后，在午夜后，当上述两个扩展活动遇到对方，虽然4000 nT的活动和前面的扩展之间的关系还不清楚。这第三个活动的突然性（2分钟内变化3000 nT）是另一个独特的特征。
[1] Global geomagnetic field data, IMAGE FUV data, and many other in situ observations are presented for the initial 10 min of the magnetic storm starting 29 October 2003 at around 0610 UT. Within 1 min after sudden commencement (SC), two independent strong westward ionospheric electrojets (>2000 nT) at the inner magnetospheric region started simultaneously, one in the evening-midnight sector and the other in the morning sector. Both activities expanded and accompanied auroral expansion. The locations (inner magnetosphere), morphologies (expansion), and intensities (>2000 nT) of both activities fall into substorm expansive phases. Having such simultaneous independent 2000 nT level expansions makes this event unique. The interplanetary magnetic field condition before the SC was not favorable in causing an AL < −2000 nT activity. A timing analysis indicates that these strong westward electrojets were most likely triggered by the interplanetary shock, with the triggering location not farther than the geosynchronous distance. They are also probably maintained by the direct energy pumping from the solar wind because cross-tail current derived from the closely located GOES-10 and Polar did not decrease very much during this period. A local but even stronger geomagnetic (nearly 4000 nT) and auroral activity started only 6 min after the start of SC at postmidnight where and when the above two expanding activities met each other, although the relation between the onset of 4000 nT activity and the preceding expansions is not clear. The suddenness of this third activity (3000 nT change within 2 min) is another unique feature.