Convective bursty flows in the near-Earth magnetotail inside 13 RE
Convective bursty flows in the near-Earth magnetotail inside 13 RE
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DOI：
10.1029/2008ja013125
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发表时间：
2009-02
影响因子：
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通讯作者：
L. Q. Zhang;Z. Liu;Wolfgang Baumjohann;Zhiwei Ma;Z. Pu;M. Dunlop;L. Lu;Junru Shi;C. Carr;H. Rème;J. Wang
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文献类型：
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作者：
L. Q. Zhang;Z. Liu;Wolfgang Baumjohann;Zhiwei Ma;Z. Pu;M. Dunlop;L. Lu;Junru Shi;C. Carr;H. Rème;J. Wang
利用双星TC-1上磁强计和离子等离子体分析仪2004年6月至2006年11月的4-S分辨率资料，统计分析了对流爆发和场向爆发的发生率。在-13R-E 180公里/S和垂直于x>；180公里/S超过30公里的区域，垂直于x和平行于x的速度矢量的X分量分别是垂直于和平行于局部磁场的X分量。统计结果表明，在-11.5 R-E附近，对流爆发流(CBF)的出现率最小，在-11.5 R-E附近，FABF的出现率突然下降，但在-11.5 R-E范围内没有明显增加。各类型爆发流的空间分布表明，与TC-1探测到的13R-E内部没有对流爆发流有关，方位向不存在偏转流动。磁场分析表明，BZ在12R-E附近存在一个极小值。这里，我们认为-11.5 R-E内部的CBF可能与-12 R-E外部的流动无关。12R-E以外的CBF可能是典型的爆发性体流，起源于20-30R-E下尾，并在12R-E外制动。最小BZ可能与流量制动密切相关。12R-E内部的CBF可能是由另一种机制产生的。最小的BZ可能容易激发不稳定性，从而引发亚暴膨胀和/或加速离子，导致CBF在内部。
With the 4-s resolution data of the magnetometer and the ion plasma analyzer on Double Star TC-1 from June to November of each year during the period of 2004-2006, we statistically analyzed the occurrence rate of both convective and field-aligned bursty flows (FABFs). In the region -13 R-E 180 km/s and V-parallel to x > 180 km/s exceeds 30 s, where V-perpendicular to x and V-parallel to x are irrespectively the X component of the velocity vector perpendicular and parallel to the local magnetic field. The statistical results show that the occurrence rate of the convective bursty flow (CBF) reached a minimum around -11.5 R-E; the occurrence rate of the FABF has a sudden decrease around -11.5 R-E, but has no clear increase inside -11.5 R-E. The spatial distribution of the all types of bursty flows shows that there had no deflection flows in the azimuthal direction related to the absence of the convective bursty flows inside 13 R-E explored by TC-1. The magnetic field analysis indicates that there exists a minimum in Bz around 12 R-E. Here, we suggest that the CBFs inside -11.5 R-E may not relate to the flows outside -12 R-E. The CBFs outside 12 R-E are likely to be the classical bursty bulk flow, originating 20-30 R-E downtail and braking outside 12 R-E. The minimum Bz may have close relation with the flow braking. The CBFs inside 12 R-E may be produced by another mechanism. The minimum Bz may be prone to the excitation of instabilities and, consequently, initiation of the substorm expansion and/or acceleration of ions resulting in CBFs inside.