Statistical study of magnetotail flux ropes near the lunar orbit

作     者：ZHAO Si Qi TIAN An Min SHI Quan Qi XIAO Chi Jie FU Sui Yan ZONG Qiu Gang WANG Hui Zi ZHANG Shuai ZHAO Shao Jie PAN Dong Xiao TENG Shang Chun LIU Yi Xing TAN Kun 

作者机构：Shandong Provincial Key Laboratory of Optical Astronomy and Solar-Terrestrial Environment School of Space Science and PhysicsShandong University School of Physics Peking University School of Earth and Space Science Peking University 

出 版 物：《Science China(Technological Sciences)》 (中国科学（技术科学英文版）)

年 卷 期：2016年第59卷第10期

页      面：1591-1596页

核心收录：

学科分类：070802[理学-空间物理学] 07[理学] 0708[理学-地球物理学] 

基　　金：supported by the Scientific Research Foundation of Shandong Province Outstanding Young Scientist Award(Grant Nos.2013BSE27132&BS2013HZ001) the Research Fund for the Doctoral Program of Higher Education of China(Grant No.20130131120073) the National Natural Science Foundation of China(Grant Nos.41304129,41322031&41574157) 

主　　题：magnetotail flux rope TCR dawn-dusk asymmetry reconnection site 

摘      要：Flux-rope/TCR events near the magnetotail lunar orbit （-67RE 〈 GSM X＊ 〈 -39RE） were studied using magnetic-field and plasma data measured by THEMIS B and C between January 2011 and March 2012. The aberrant coordinate GSM＊, where the X＊ axis is rotated 4° relative to GSM-X, was used to count the occurrence rate. The number ratio of earthward to tailward events was about 3：5. Moreover, the event occurrence rate distribution showed a clear dawn-dusk asymmetry distribution, with dusk-side events accounting for 57.98%. A superposed epoch analysis of the flux-rope events showed that earthward events had a shorter duration in the leading than in the trailing part. Earthward events also displayed a lower temperature and a lower flow speed than tailward events. We studied the relationship between the event occurrence rate and geomagnetic activity level even further. The occurrence rate of tailward flux-rope/TCR events increases with increasing AE-index, whereas earthward events occur mainly in the relatively quiet period of geomagnetic activity （AE - 100-300 nT）. Flux-rope/TCR events identi- fied within a 10 mm time frame were treated as belonging to a single reconnection event. By comparing the occurrence rates of earthward and tailward events along X＊, we estimated the most likely location of the near-Earth reconnection site as X＊ = -36RE.