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| 1 | Observations of kinetic Alfvén waves by THEMIS near a substorm onset显示文摘Low frequency electromagnetic fluctuations in the vicinity of a magnetospheric substorm onset were investigated using simultaneous observations by THEMIS multiple probes in the near-Earth plasma sheet in the magnetotail.The observations indicate that in the vicinity of a substorm onset,kinetic Alfvén waves can be excited in the high-βplasma sheet(β=2μ0nT/B 2 ,the ratio of plasma thermal pressure to magnetic pressure)within the near-Earth magnetotail.The kinetic Alfvén wave has a small spatial scale in the high-βplasma.The parallel electric field accompanying kinetic Alfvén waves accelerates the charged particles along the magnetic field.The kinetic Alfvén waves play an important role in the substorm trigger process,and possibly in the formation of a substorm current wedge. | DUAN SuPing LIU ZhenXing ANGELOPOULOS Vassilis | 2012 | Chinese Science Bulletin2012，57，12： | 3 |
| 2 | Ion flux dropout observed near dipolarization front显示文摘An ion flux dropout near the dipolarization front(DF) at around XGSM=-11 REin the Earth's plasma sheet was observed by Time History of Events and Macroscale Interaction during substorms(THEMIS) on March31, 2009. The ion differential energy fluxes at energies from 450 e V to 150 ke V measured by the ESA and SST instruments from THC began to decrease about 2 s before the detection of the DF and reached a local minimum 6 s later. Then, the ion fluxes gradually increased to form a dropout around the DF. The spatial extent of the dropout was about 4,000 km. For energies above 20 ke V, the ion fluxes after the dropout are greater than those before it,contrary to the fluxes at energies below 20 ke V. The associated ion density variation indicates that the ion flux dropout coincides with the ion density dropout. Taking advantage of multipoint observations, THD, THC, and THE detected the same DF consecutively. Only THC detected an obvious ion flux dropout; THD observed an indistinct one about 2 s before THC; no high-energy(E [ 30 ke V) ion flux dropout was observed by THE. Our study suggests that the ion flux dropout may evolve withthe earthward-propagating DF, and its properties can depend on locations relative to the DF. | Xueling Shi Tao Chen Lingqian Zhang Suping Duan Jiang Liu Zhaohai He | 2014 | Chinese Science Bulletin2014，59，34： | 1 |
| 3 | Double Star TC-1 observation of the earthward flowing plasmoids in the near magnetotail显示文摘We analyze Double Star TC-1 magnetic field data from July to September in 2004 and find that plas-moids exist in the very near-Earth magnetotail. It is the first time that TC-1 observes the plasmoids inthe magnetotail at X > ?13 RE. According to the difference of the magnetic field structure in plasmoids,we choose two typical cases for our study: the magnetic flux rope on August 6 with the open magneticfield and the magnetic loop on September 14 with the closed magnetic field. Both of the cases are as-sociated with the high speed earthward flow and the magnetic loop is related to a strong substorm. Theions can escape from the magnetic flux rope along its open field line, but the case of the closed mag-netic loop can trap the ions. The earthward flowing plasmoids observed by TC-1 indicate that the mul-tiple X-line magnetic reconnection occurs beyond the distance of X=?10 RE from the earth. | ZHANG YongCun LIU ZhenXing SHEN Chao DUAN SuPing HE ZhaoHai C M CARR H REME | 2007 | Chinese Science Bulletin2007，52，13： | 1 |
| 4 | Multiple satellites observation evidence:High-m Poloidal ULF waves with time-varying polarization states显示文摘We report multi-spacecraft observations of ULF waves from Van Allen Probes(RBSP), Magnetospheric Multiscale(MMS), Time History of Events and Macroscale Interactions during Substorm(THEMIS), and Geostationary Operational Environmental Satellites(GOES).On August 31, 2015, global-scale poloidal waves were observed in data from RBSP-B, GOES and THEMIS from L=4 to L=8 over a wide range of magnetic local time(MLT). The polarization states varied towards purely poloidal polarity. In two consecutive orbits over 18 hours, RBSP-A and RBSP-B recorded gradual variation of the polarization states of the poloidal waves; the ratio(|B_a|/|B_r|) decreased from 0.82 to 0.13. After the variation of polarization states, the poloidal ULF waves became very purely poloidal waves, localized in both L and MLT. We identify the poloidal wave as second harmonic mode with a large azimuthal wave number(m) of –232. From RBSP particle measurements we find evidence that the high-m poloidal waves during the polarization variations were powered by inward radial gradients and bump-on-tail ion distributions through the N=1 drift-bounce resonance. Most of the time, the dominant free energy source was inward radial gradients, compared with the positive gradient in the energy distribution of the bump-on-tail ion distributions. | Chao Wei Lei Dai SuPing Duan Chi Wang YuXian Wang | 2019 | Earth and Planetary Physics2019，3，3： | 1 |
| 5 | Characteristics of magnetic dipolarizations in the vicinity of the substorm onset region observed by THEMIS显示文摘With conjunction observations of electromagnetic fields and plasma from Time History of Events and Macroscale Interactions during Substorm(THEMIS)in the near-Earth magnetotail,we investigate the spatial and temporal properties of substorm dipolarizations in the near-Earth plasma sheet(NEPS)during a substorm at 03:23 UT on 12 February 2008.Substorm dipolarizations with different features are detected by three near-Earth THEMIS probes(THA(P5),THD(P3)and THE(P4))in the magnetotail.In the current sheet with a large plasma beta value(β>2,whereβis the ratio of the plasma thermal pressure to the magnetic pressure),the dipolarization within the substorm onset region,(−10.4,2.8,−2.6)RE_gsm,has a large initial magnetic field elevation angle,θ>60°,θ=arctan(Bz/(Bx2+By2)1/2),and is accompanied by energetic ion(tens to hundred keV)dispersionless injection detected by THD(P3).This substorm onset dipolarization is characterized by Bx and By components around 0 nT with significant fluctuations.The Bz component increases sharply and its subsequent magnitude approaches the total magnetic field,Bt.The maximum value of the elevation angle approaches 85°during the later substorm expansion phase.In the NEPS withβ~1,the dipolarization outside the substorm onset region is characterized by a magnetic elevation angle with a small beginning value ofθ<45°and following multi-step enhancements during the substorm expansion phase.The maximum value of the elevation angle approaches to 70°during the later substorm expansion phase.Our observation results indicate that characteristics of dipolarization with a large beginning elevation angle within the substorm onset region provide a new indicator to identify substorm onset location. | SuPing Duan Chi Wang Weining William Liu ZhaoHai He | 2021 | Earth and Planetary Physics2021，5，3： | 1 |
| 6 | Responses of properties in the plasma sheet and at the geosynchronous orbit to interplanetary shock显示文摘On July 22, 2004, the WIND spacecraft detected a typical interplanetary shock. There was sustaining weak southward magnetic field in the preshock region and the southward field was suddenly enhanced across the shock front (i.e., southward turning). When the shock impinged on the magnetosphere, the magnetospheric plasma convection was abruptly enhanced in the central plasma sheet, which was directly observed by both the TC-1 and Cluster spacecraft located in different regions. Simultaneously, the Cluster spacecraft observed that the dawn-to-dusk electric field was abruptly enhanced. The variations of the magnetic field observed by TC-1, Cluster, GOES-10 and GOES-12 that were distributed in different regions in the plasma sheet and at the geosynchronous orbit are obviously distinct. TC-1 observations showed that the magnetic intensity kept almost unchanged and the elevation angle decreased, but the Cluster spacecraft, which was also in the plasma sheet and was further from the equator, observed that the magnetic field was obviously enhanced. Simultaneously, GOES-12 located near the midnight observed that the magnetic intensity sharply increased and the elevation angle decreased, but GOES-10 located in the dawn side observed that the magnetic field was merely compressed with its three components all sharply increasing. Furthermore, the energetic proton and electron fluxes at nearly all channels observed by five LANL satellites located at different magnetic local times (MLTs) all showed impulsive enhancements due to the compression of the shock. The responses of the energetic particles were much evident on the dayside than those on the nightside. Especially the responses near the midnight were rather weak. In this paper, the possible reasonable physical explanation to above observations is also discussed. All the shock-induced responses are the joint effects of the solar wind dynamic pressure pulse and the magnetic field southward turning. | YAO Li LIU ZhenXing ZUO PingBing ZHANG LingQian DUAN SuPing | 2009 | Chinese Science Bulletin2009，54，18： | 0 |
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