Low-frequency fluctuations in the magnetosheath: Double Star TC-1 and Cluster observations  

作　　者：DU Jian1,2 WANG Chi1, SONG Pu3,4 & ZHANG TieLong5 1 State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China 2 Graduate School, Chinese Academy of Sciences, Beijing 100049, China 3 Earth, Environmental and Atmospheric Sciences Department, University of Massachusetts, Lowell, Mas-sachusetts MA 01854, USA 4 Center for Atmospheric Research, University of Massachusetts, Lowell, Massachusetts MA 01854, USA 5 Space Research Institute, Austrian Academy of Sciences, Graz A-8010, Austria 

出　　处：《Science China(Technological Sciences)》2008年第10期1626-1638,共13页中国科学（技术科学英文版）

基　　金：the CAS (Grant No. KJCX2-YW-T13);the National Natural Science Foundation of China (Grant Nos. 40621003, 40628003, 40390150)

摘　　要：The magnetic field variations are analyzed in the range of time periods from 4 s to 240 s in the magnetosheath observed by the Double Star TC-1 and Cluster in 2004. The characteristics of the magnetic field fluctuations are strongly controlled by the angle between the upstream interplanetary magnetic field (IMF) and the normal of the bow shock. Generally speaking, the magnetic field fluctuations in the quasi- parallel magnetosheath are more intense than those in the quasi-perpendicular ones. Almost purely compressional waves are found in the quasi-perpendicular magnetosheath. With the increase of the local plasma β, both the magnitude and direction of the magnetic field fluctuate more intensely. There exists an inverse correlation between the local temperature anisotropy T⊥/T|| and the plasma β.The magnetic field variations are analyzed in the range of time periods from 4 s to 240 s in the magnetosheath observed by the Double Star TC-1 and Cluster in 2004. The characteristics of the magnetic field fluctuations are strongly controlled by the angle between the upstream interplanetary magnetic field (IMF) and the normal of the bow shock. Generally speaking, the magnetic field fluctuations in the quasi-parallel magnetosheath are more intense than those in the quasi-perpendicular ones. Almost purely compressional waves are found in the quasi-perpendicular magnetosheath. With the increase of the local plasma β, both the magnitude and direction of the magnetic field fluctuate more intensely. There exists an inverse correlation between the local temperature anisotropy T ⊥/T∥ and the plasma β.

关 键 词：LOW-FREQUENCY FLUCTUATIONS MAGNETOSHEATH MHD INSTABILITIES 

分 类 号：P353[天文地球—空间物理学]