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| 1 | Numerical study on ULF waves in a dipole field excited by sudden impulse显示文摘A three-dimensional numerical model is employed to investigate ULF waves ex-cited by the sudden impulse (SI) of the solar wind dynamic pressure interacting with a dipole magnetosphere. We focus on the solar wind-magnetosphere energy coupling through ULF waves, and the influences of the SI spectrum on the cavity mode structure and the energy deposition due to field line resonances (FLRs) in the magnetosphere. The numerical results show that for a given SI lasting for 1 min with amplitude of 50 mV/m impinging on the subsolar magnetopause, the total ULF energy transported from the solar wind to the magnetosphere is about the magni-tude of 1014 J. The efficiency of the solar wind energy input is around 1%, which depends little on the location of the magnetopause in the model. It is also found that the energy of the cavity mode is confined in the region near the magnetopause, whereas, the energy of the toroidal mode may be distributed among a few specific L-shells. With a given size of the model magnetosphere and plasma density distri-bution, it is shown that the fundamental eigenfrequency of the cavity mode and the central locations of the FLRs do not vary noticeably with the power spectrum of the SI. It is worth noting that the spectrum of the SI affects the excitation of higher harmonics of the global cavity mode. The broader the bandwidth of the SI is, the higher harmonics of cavity mode could be excited. Meanwhile, the corresponding FLRs regions are broadened at the same time, which implies that the global cavity modes and toroidal modes can resonate on more magnetic L-shells when more harmonics of the global cavity modes appear. | YANG Biao FU SuiYan ZONG QiuGang WANG YongFu ZHOU XuZhi PU ZuYin XIE Lun | 2008 | Science China(Technological Sciences)2008，51，10： | 12 |
| 2 | Multi-spacecraft observations of ULF waves during the recovery phase of magnetic storm on October 30, 2003显示文摘Based on observations obtained by Cluster C1, GOES 10, 12, and Polar, the global ULF wave properties are studied during the recovery phase of a very intense magnetic storm-Halloween storm (October 31, 2003, 21:00-23:00 UT). The results indicate that the ULF waves’ properties observed by different satellites, such as amplitude, period, etc. show large variations. This can be interpreted as that Field Line Resonance (FLR) might take place in the region where Cluster C1 passed. The compressional wave of the cavity mode coupled with FLR’s shear Alfven wave and fed energy to the latter, forming a large-amplitude toroidal mode. From the point of period, Cluster C1 observed the shortest period, GOES 10, 12 observed the middle, while Polar observed the longest. The wave period of toroidal mode observed by Cluster C1 kept almost unchanging when Cluster C1 passed L range from 11.7 to 5.3. Using the Squared Wavelet Coherence analysis method, we estimated that the FLR region in the dayside magnetosphere could expand to at least 4 local time widths. The toroidal mode observed by Polar was a standing wave, while the pol-oidal mode was a propagating wave, the observation results could be well ex-plained by the waveguide mode theory. Since the solarwind speed Vx was -800 km/s and the dynamic pressure varied little, we speculated that the source of the ULF wave was the Kelvin-Helmholtz instability at the magnetopause triggered by high speed solarwind. | YongFu Wang SuiYan Fu QiuGang Zong Biao Yang ZuYin Pu Lun Xie XuZhi Zhou | 2008 | Science China(Technological Sciences)2008，51，10： | 11 |
| 3 | High-speed flowing plasmas in the Earth’s plasma sheet显示文摘A research topic of great interest to the space physics community is the observation of plasmas flowing at hundreds of kilometers per second in the Earth’s plasma sheet. Although considerable effort has been made to understand the source of fast-flowing plasmas, many questions remain unanswered about the mechanisms that produce high-speed flows and the effects they have on magnetospheric disturbances, especially their contributions to magnetospheric convection and substorms. In this paper, we discuss briefly the history of high-speed flows and review the proposed mechanisms, signatures of high-speed flows in auroras and their interaction with the background plasma. We then summarize the relationships between high-speed flows and magnetic structures, discuss questions associated with substorms, and finally pose several important scientific questions that need to be addressed. | FU SuiYan SHI QuanQi WANG Chi PARKS George ZHENG Ling ZHENG Hao SUN WeiJie | 2011 | Chinese Science Bulletin2011，56，12： | 9 |
| 4 | Radial propagation of magnetospheric substorm-injected energetic electrons observed using a BD-IES instrument and Van Allen Probes显示文摘In cases where substorm injections can be observed simultaneously by multiple spacecraft,they can help elucidate the potential mechanisms of particle transport and energization,of great importance to understanding and modeling the magnetosphere.In this paper,using data returned from the BeiDa-IES(BD-IES) instrument onboard a satellite in an inclined(55°) geosynchronous orbit(IGSO),in combination with two geo-transfer orbiting(GTO) satellite Van Allen Probes(A and B),we analyze a substorm injection event that occurred on the 16 th of October 2015.During this substorm injection,the IGSO onboard BD-IES was outbound,while both Van Allen Probe satellites(A and B) were inbound,a configuration of multiple trajectories that provides a unique opportunity to simultaneously investigate both the inward and outward radial propagation of substorm injection.Indicated by AE/AL indices,this substorm was closely related to an IMF/solar wind discontinuity that showed a sharp change in IMF Bz direction to the north.The innermost signature of this substorm injection was detected by Van Allen Probes A and B at L-3.7,while the outermost signature was observed by the onboard BD-IES instrument at L~\0.These data indicate that the substorm had a global,rather than just local,effect.Finally,we suggest that electric fields carried by fast-mode compressional waves around the substorm injection are the most likely candidate mechanism for the electron injection signatures observed in the inner- and outermost inner magnetosphere. | ZONG QiuGang HAO YiXin ZOU Hong FU SuiYan ZHOU XuZhi REN Jie WANG LingHua YUAN ChongJing LIU ZhiYang JIA XiangHong QUAN Lin LIU Ying WANG YongFu | 2016 | Science China Earth Sciences2016，59，7： | 8 |
| 5 | Neural Network and GBSM Based Time-Varying and Stochastic Channel Modeling for 5G Millimeter Wave Communications显示文摘In this work,a frame work for time-varying channel modeling and simulation is proposed by using neural network(NN)to overcome the shortcomings in geometry based stochastic model(GBSM)and simulation approach.Two NN models are developed for modeling of path loss together with shadow fading(SF)and joint small scale channel parameters.The NN models can predict path loss plus SF and small scale channel parameters accurately compared with measurement at 26 GHz performed in an outdoor microcell.The time-varying path loss and small scale channel parameters generated by the NN models are proposed to replace the empirical path loss and channel parameter random numbers in GBSM-based framework to playback the measured channel and match with its environment.Moreover,the sparse feature of clusters,delay and angular spread,channel capacity are investigated by a virtual array measurement at 28 GHz in a large waiting hall. | Xiongwen Zhao Fei Du Suiyan Geng Ningyao Sun Yu Zhang Zihao Fu Guangjian Wang | 2019 | China Communications2019，16，6： | 7 |
| 6 | Enhanced anti-sunward flow near local noon during a period of horizontal IMF and high solar wind velocity V_Y显示文摘It is believed that a southward interplanetary magnetic field (IMF) is mainly responsible for the energy input from solar wind into the magnetosphere.This paper presents an unusual case of strong anti-sunward plasma flow (up to 2 km/s) in the polar cap ionosphere and large cross-polar cap potential (CPCP) during a period of horizontal IMF (|BZ| < 2 nT) observed by both ACE (at the L1 point) and Geotail (on the dusk flank of the magnetosheath).The CPCP is even higher than that under preceding BZ ≈-23 nT.Furthermore,GOES8 observed that the magnetosheath field turns northward as the anti-sunward plasma flow and CPCP start to increase,which implies that the magnetosheath field interacting with the Earth's magnetopause has significantly rotated and differs from the IMF observed by ACE and Geotail.In accordance with previous theoretical work,we suggest that the magnetic field line draping produces a southward magnetosheath field and enhances anti-sunward plasma flow and the CPCP. | WEI Yong ZONG QiuGang PU ZuYin WAN WeiXing LIU JianJun FU SuiYan SHI QuanQi | 2011 | Chinese Science Bulletin2011，56，11： | 7 |
| 7 | Ultra low frequency waves observed by Double Star TC-1 in the plasmasphere boundary layer显示文摘The characteristic and properties of ULF waves in the plasmasphere boundary layer during two very quiet periods are present. The ULF waves were detected by Double Star TC-1 when the spacecraft passed through the plasmasphere in an outbound and inbound trajectories, respectively. A clear association between the ULF waves and periodic variations of energetic ions fluxes was observed. The ob-servations showed that the wave frequency was higher inside the plasmasphere than outside. The mechanism generating these ULF waves and possible diagnos-ing of the 'classical plasmapause' location with the ULF wave were discussed. | XIE Lun ZHANG XiaoJia PU ZuYin WANG YongFu FU SuiYan ZONG QiuGang | 2008 | Science China(Technological Sciences)2008，51，10： | 7 |
| 8 | Analysis of magnetotail flux rope events by ARTEMIS observations显示文摘Three earthward flowing magnetic flux ropes observed in the duskside plasma sheet at geocentric solar magnetospheric coordinate X~–55 Re by P1 and P2 of acceleration,reconnection,turbulence and electrodynamics of moon’s interaction with the sun mission during 13:00–15:00 UT on July 3,2012,were studied.The morphologies of the flux ropes were studied in detail based on Grad-Shfranov reconstruction method and electronic pitch angle distribution data.It is found that(1)the flux rope cross-sectional dimensions are 1.0 Re×0.78 Re,1.3 Re×0.78 Re,and 2.5 Re×1.25 Re,respectively.The magnetic field lines were asymmetric about the center with field line compression on both sides of the current sheet at the leading region;(2)the electron energy flux data presented asymmetry with larger electron flux and lower temperature in the precursor region.The flux ropes were blocked by the resistance of compressed particle density in the front central plasma sheet and the enhanced magnetic field on its sides;and(3)it is found that the flux rope has a layered structure.From inside out,event 1 can be divided into three regions,namely electronic depletion core region,closed field line region,and the caudal area possible with fields connected with the ionosphere.It suggests that the flux ropes cannot merge with the tail magnetic field lines near the lunar orbit.Especially,the flux rope asymmetrical shape reflects the different reconnection processes that caused it on both sides of the magnetic structure.The events shown in this paper support the multiple X-line magnetic reconnection model for flux ropes with in situ observations. | TIAN AnMin SHI QuanQi ZONG QiuGang DU Jian FU SuiYan DAI YaNan | 2014 | Science China(Technological Sciences)2014，57，5： | 5 |
| 9 | THEMIS observation of a magnetotail current sheet flapping wave显示文摘A flapping wave was observed by THEMIS-B(P1)and THEMIS-C(P2)probes on the dawn side of the magnetotail,while the solar wind was generally stable.The magnetic activity was quite weak,suggesting that this flapping wave was generated by an internal instability,which normally occurs during magnetic quiet times.Our analysis shows that the flapping wave was propagating downward with a tail-aligned scale of at least 3.7 R E and did not show much change in shape during its propagation from P1 to P2.Correlation analysis employed to estimate the time lag between the corresponding half waveforms of P1 and P2 shows that the propagating velocities along the current sheet normal directions were close to each other in the beginning,but increased linearly later on.The average wavelength of the flapping wave is approximately 4 R E.Theoretical analysis suggests that the ballooning type wave model may not be the mechanism for the observed flapping wave,but that the magnetic double-gradient instability model is a more plausible candidate. | Weijie Sun Suiyan Fu Quanqi Shi Qiugang Zong Zhonghua Yao Ting Xiao George Parks | 2014 | Chinese Science Bulletin2014，59，2： | 3 |
| 10 | Braking of high-speed flows in the magnetotail:THEMIS joint observations显示文摘The motion and deceleration processes of plasma sheet high-speed flows have great significance to magnetospheric particle acceleration,magnetic field perturbation,magnetic flux transport,triggering of substorm,and the current system formation in the magnetotail.From February to April 2009,two satellites of the Time History of Events and Macroscale Interactions during Substorms mission,THA and THE,were often separated largely in Z direction,but had small X and Y separations.Such special configuration allows simultaneous observations of highspeed flows at the center and boundary of the plasma sheet.Based on selected case study and statistical analysis,it is found that for about 89%of the events we selected,the probe further away from the neutral sheet observed the high-speed flow earlier than the one close to the center,and the flow is mainly field aligned.And for about 95%events the probe further away from the neutral sheet observed higher X component of the plasma flow.With the hypothesis that parallel flow keeps the same speed during its earthward propagation while central plasma sheet stream uniformly or suddenly brakes on its way to the earth,we deduced the position where the deceleration begins to be between 13 Re and 17 Re downtail,where thenear-earth reconnection is supposed to occur.In addition,our statistical results show that dipolarization fronts observed in the central plasma sheet are more prominent than those observed in the plasma sheet boundary layer ahead of the high-speed flow. | Wensai Shang Zhonghua Yao Quanqi Shi Weijie Sun Suiyan Fu Jiang Liu Anmin Tian Qiugang Zong Zuyin Pu Ting Xiao Vassilis Angelopoulos | 2014 | Chinese Science Bulletin2014，59，3： | 3 |
| 11 | Shape and position of Earth's bow shock near-lunar orbit based on ARTEMIS data显示文摘Earth's bow shock is the result of interaction between the supersonic solar wind and Earth's magnetopause. However, data limitations mean the model of the shape and position of the bow shock are based largely on near-Earth satellite data. The model of the bow shock in the distant magnetotail and other factors that affect the bow shock, such as the interplanetary magnetic field(IMF) B_y, remain unclear. Here, based on the bow shock crossings of ARTEMIS from January 2011 to January 2015, new coefficients of the tail-flaring angle a of the Chao model(one of the most accurate models currently available) were obtained by fitting data from the middle-distance magnetotail(near-lunar orbit, geocentric distance -20R_E>X>-50R_E). In addition, the effects of the IMF B_y on the flaring angle a were analyzed. Our results showed that:(1) the new fitting coefficients of the Chao model in the middle-distance magnetotail are more consistent with the observed results;(2) the tail-flaring angle a of the bow shock increases as the absolute value of the IMF B_y increases. Moreover, positive IMF B_y has a greater effect than negative IMF B_y on flaring angle. These results provide a reference for bow shock modeling that includes the IMF B_y. | LIU Ji SHI QuanQi TIAN AnMin Lü JianYong WU Hao WANG Ming FU SuiYan YANG YuChen ZONG QiuGang ZHANG Jiang FENG YongYong PU ZuYin | 2016 | Science China Earth Sciences2016，59，8： | 3 |
| 12 | THEMIS observations of two substorms on February 26,2008显示文摘Two substorms occurred at ~04:05 and ~04:55 UT on February 26,2008 are studied with the in-situ observations of THEMIS satellites and ground-based aurora and magnetic field measurements.Angelopoulos et al.have made a comprehensive study of the 04:55 UT event.We showed detailed features of the two substorms with much attention to the first event and to the rela-tionship between mid-tail magnetic reconnection(MR) and substorm activities.It was found that in the earlier stage of each substorm,a first auroral intensification occurred 2-3 min soon after the start of mid-tail MR,followed by a slow and very lim-ited expansion.The auroral arcs were weak,short-lived,and localized,characterizing all features of a pseudobreakup.We re-garded the first auroral brightening as the initial onset of the substorms.A few minutes later,a second stronger auroral intensification appeared,followed by quick and extensive expansions.It was interesting to note that the second brightening and related poleward expansion happened almost simultaneously(within a couple of minutes) with the onset of earthward flow and dipolarization in the near-Earth tail and other phenomenon of the substorm expansion phase.We thus regarded the second auroral brightening as the major onset of the substorms.Furthermore,it was seen that during the growth phase of the two substorms,the polar cap open flux Ψ kept increasing,while it quickly reduced during the substorm expansion and recovery phase.These variations of Ψ implied that the evolution of the two substorm expansion phases were closely related to MR of tail lobe open field lines.Analysis of substorm activities revealed that the two events studied were small substorms;while estimate of MR rate indicated that the MR processes in the two substorms were weak.The aforementioned observations suggested that mid-tail MR initiated the pseudobreakup first;the earthward flow generated by MR transported magnetic flux and energy to the near-Earth tail to cause the formation of SCW and CD,which induced near-Earth dipolarization and major auroral brightening,and eventually led to the onset of the substorm expansion phase.These results were clearly consistent with the picture of NENL and RCS models and supported the two step initiation scenario of substorms. | CHU XiangNing PU ZuYin CAO Xin WANG Jue V.MISHIN V.ANGELOPOULOS LIU Jiang WEI Yong K.H.GLASSMEIER J.MCFADDEN D.LARSON S.MENDE H.FREY C.T.RUSSELL I.MANN D.SIBECK ZONG QiuGang FU SuiYan XIE Lun T.I.SAIFUDINOVA M.V.TOLOCHKO L.A.SAPRONOVA H.REME E.LUCEK | 2010 | Science China(Technological Sciences)2010，53，5： | 3 |
| 13 | Review of Mercury's dynamic magnetosphere:Post-MESSENGER era and comparative magnetospheres显示文摘This review paper summarizes the research of Mercury’s magnetosphere in the Post-MESSENGER era and compares its dynamics to those in other planetary magnetospheres,especially to those in Earth’s magnetosphere.This review starts by introducing the planet Mercury,including its interplanetary environment,magnetosphere,exosphere,and conducting core.The frequent and intense magnetic reconnection on the dayside magnetopause,which is represented by the flux transfer event'shower',is reviewed on how they depend on magnetosheath plasma β and magnetic shear angle across the magnetopause,followed by how it contributes to the flux circulation and magnetosphere-surface-exosphere coupling.In the next,Mercury’s magnetosphere under extreme solar events,including the core induction and the reconnection erosion on the dayside magnetosphere,as well as the responses of the nightside magnetosphere,are reviewed.Then,the dawn-dusk properties of the plasma sheet,including the features of the ions,the structure of the current sheet,and the dynamics of magnetic reconnection,are summarized.The last topic is devoted to the particle energization in Mercury’s magnetosphere,which includes the energization of the Kelvin-Helmholtz waves on the magnetopause boundaries,reconnection-generated magnetic structures,and the cross-tail electric field.In each chapter,the last section discusses the open questions related to each topic,which can be considered by the simulations and the future spacecraft mission.We end this paper by summarizing the future Bepi Colombo opportunities,which is a joint mission of ESA and JAXA and is en route to Mercury. | Weijie SUN Ryan MDEWEY Sae AIZAWA Jia HUANG James A.SLAVIN Suiyan FU Yong WEI Charles F.BOWERS | 2022 | Science China Earth Sciences2022，65，1： | 2 |
| 14 | Continuous lobe reconnectionin the mid-tail and its relationship to substorms:Cluster observations of continuous lobe reconnection in the mid-magneto tail显示文摘When the IMF turns southward, a great amount of magnetic energy is stored in the magnetotail, and the electric field across the magnetotail substantially en-hances. As long as magnetic reconnection (MR) in the mag-netotail initiates and continues, the magnetic field and plasma in the central plasma sheet are carried away to the near-Earth and down to the tail, the magnetic field and plasma in the lobe region enter the CPS and are involved in MR. We call this process “Continuous Lobe Reconnection (CLR)”. In this paper a detailed analysis of Cluster observa-tion of MR through 2001―2003 is made. Plenty of CLR events are found that led to considerable changes of tail con-figuration, appearance of BBF, as well as large-scale bubbles in which both plasma temperature and number density sub-stantially decrease. It is shown that in general CLR events last for dozens of minutes and have good correspondence to substorm initiation under the condition of continuous southward IMF. | CAO Xin PU Zuyin ZHANG Hui FU Suiyan XIAO Chijie LIU Zhenxing J. B. cao A. Korth M. Frazen Q. G. Zong H. Reme K. H. Glassmeier | 2005 | Chinese Science Bulletin2005，50，18： | 2 |
| 15 | Non-storm erosion of MeV electron outer radiation belt down to L^(*)<4.0 associated with successive enhancements of solar wind density显示文摘We report an unusual non-storm erosion event of outer zone MeV electron distribution during three successive solar wind number density enhancements(SWDEs)on November 27-30,2015.Loss of MeV electrons and energy-dependent narrowing of electron pitch angle distributions(PAD)first developed at L^(*)=5.5 and then moved down to L^(*)<4.According to the evolution of the electron phase space density(PSD)profile,losses of electrons with small pitch angles at L^(*)>4 during SWDE1 are mainly due to outward radial diffusion.However during SWDE2&3,scattering loss due to EMIC waves is dominant at 4 | Ying Xiong Lun Xie SuiYan Fu BinBin Ni ZuYin Pu | 2021 | Earth and Planetary Physics2021，5，6： | 2 |
| 16 | Altitude of the upper boundary of AAR based on observations of ion beams in inverted-V structures:A case study显示文摘Outflowing ion beams forming four successive inverted-V structures in the energy-time spectrograms of H+, He+, and O+ were observed at an altitude of 3.4 RE by Cluster satellites travelling above the auroral acceleration region (AAR) in the southern hemisphere on February 14, 2001. Energization by negative U-shaped potential structures in the AAR is believed to be responsible for the formation of these outflowing ion inverted-V structures. Thus, utilizing the different motion properties of the three ion species, the altitude of the upper boundary of the AAR is estimated to be ~11100 km. Moreover, based on multi-satellite observations, each of these U-shaped potential structures involved in this event crosses the latitudinal direction at ~0.4°–1° invariantlatitude (ILAT), moving poleward at an average speed of ~0.2° ILAT per minute, before disappearing at ~71.5° ILAT. | CUI YanBo FU SuiYan ZONG QiuGang XIE Lun SUN WeiJie ZHAO Duo WU Tong George PARKS | 2016 | Science China Earth Sciences2016，59，7： | 2 |
| 17 | Corotating drift-bounce resonance of plasmaspheric electron with poloidal ULF waves显示文摘The purpose of this paper is to understand how low energy plasmaspheric electrons respond to ULF waves excited by interplanetary shocks impinging on magnetosphere. It is found that both energy and pitch angle dispersed plasmaspheric electrons with energy of a few eV to tens of eV can be generated simultaneously by the interplanetary shock. The subsequent period of successive dispersion signatures is around 40 s and is consistent with the ULF wave period(third harmonic). By tracing back the energy and pitch angle dispersion signatures, the position of the electron injection region is found to be off-equator at around -32° in the southern hemisphere. This can be explained as the result of injected electrons being accelerated by higher harmonic ULF waves(e.g. third harmonic) which carry a larger amplitude electric field off-equator. The dispersion signatures are due to the flux modulations(or accelerations) of ' local' plasmaspheric electrons rather than electrons from the ionosphere. With the observed wave-borne large electric field excited by the interplanetary shock impact, the kinetic energy can increase to a maximum of 23 percent in one bouncing cycle for plasmaspheric electrons satisfying the drift-bounce resonance condition by taking account of both the corotating drift and bounce motion of the local plasmaspheric electron. | Qiu-Gang Zong YongFu Wang Jie Ren XuZhi Zhou SuiYan Fu Robert Rankin Hui Zhang | 2017 | Earth and Planetary Physics2017，1，1： | 2 |
| 18 | Solar cycle dependence of the seasonal variation of auroral hemispheric power显示文摘Although much has been done on the hemispheric asymmetry (or seasonal variations) of auroral hemispheric power (HP), the dependence of HP hemispheric asymmetry on solar cycle has not yet been studied. We have analyzed data during 1979-2010 and investigated the dependence of HP hemispheric asymmetry/seasonal variation for the whole solar cycle. Here we show that (1) the hemispheric asymmetry of HP is positively correlated to the value of solar F10.7 with some time delay; (2) it is closely related to the coupling function between the solar wind and magnetosphere; and (3) the winter hemisphere receives more auroral power than the summer hemisphere for Kp ~0 to 6. The statistic results can be partly understood in the framework of the ionospheric conductivity feedback model. The similarity and differences between our results and previous results are discussed in the paper. | ZHENG Ling FU SuiYan ZONG QuiGang PARKS George WANG Chi CHEN Xi | 2013 | Chinese Science Bulletin2013，58，4： | 2 |
| 19 | Magnetic storms in Mercury's magnetosphere显示文摘We present evidence of geomagnetic storms in Mercury’s magnetosphere based on MESSENGER magnetic field observations made just before the probe impacted the planet.Our findings answer the question of whether geomagnetic storms can occur in other planetary magnetospheres.The interaction of the solar wind with Mercury’s magnetosphere is known to involve flux transfer events in the dayside magnetosphere,plasmoids and flux ropes in the magnetotail,and substorm-like processes,all of which occur morphologically similar to Earth but with significant differences.The significantly weaker magnetic field,smaller magnetosphere,and much faster timescale of processes around Mercury,when compared with Earth,enable charged particles to escape its magnetosphere more efficiently through magnetopause shadowing and direct bombard of the surface.Our analysis of MESSENGER’s data during a coronal mass ejection(CME)proves that,despite these substantial differences,a bifurcated ring current can form in Mercury’s magnetosphere that initiates magnetic storms under strong solar wind driving. | ZONG QiuGang ZHAO JiuTong LIU JianJun FU SuiYan SUN WeiJie ZHANG Hui LE Guan RANKIN Robert WEI Yong | 2022 | Science China(Technological Sciences)2022，65，6： | 1 |
| 20 | Propagation properties of foreshock cavitons: Cluster observations显示文摘Foreshock cavitons are transient phenomena observed in the terrestrial foreshock region.They are characterized by a simultaneous depression of magnetic field magnitude and plasma density,which are bounded with enhancements of these two parameters and surrounded by ultralow frequency(ULF)waves.Previous studies focused on the interplanetary magnetic field(IMF)conditions,solar wind(SW)conditions,and the growth of the foreshock waves related to the generation of foreshock cavitons.Previously,a multipoint spacecraft analysis method using Cluster data was applied to analyze only two foreshock cavitons,and this method did not consider uncertainties.In this study,multipoint spacecraft analysis methods,including the timing method,the minimum directional derivative(MDD)method,and the spatiotemporal difference(STD)method are applied to determine the velocity in both spacecraft and solar wind frames.The propagation properties show good agreement with previous results from simulations and observations that most cavitons move sunward in the solar wind frame,with the velocities larger than the Alfvén speed.The propagation properties of foreshock cavitons support the formation mechanism of cavitons in previous simulations,which suggested that cavitons are formed due to the nonlinear evolution of compressive ULF waves.We find that there is clear decreasing trend between the size of cavitons and their velocity in the solar wind frame.In addition,the timing method considering errors has been applied to study the evolution properties by comparing the velocities with errors of the leading and trailing edges,and we identify three stable cavitons and one contracting caviton,which has not been studied before.Most cavitons should remain stable when they travel toward the Earth’s bow shock.The relationship between the size of foreshock cavitons and their distance from the bow shock is also discussed. | WANG MengMeng YAO ShuTao SHI QuanQi ZHANG Hui TIAN AnMin DEGELING Alexander William ZHANG Shuai GUO RuiLong SUN WeiJie LIU Ji BAI ShiChen SHEN XiaoChen ZHU XiaoQiong FU SuiYan PU ZuYin | 2020 | Science China(Technological Sciences)2020，63，1： | 1 |
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