Progress of Solar Corona and Interplanetary Physics in China : 2010 − − 2012 ∗

The scientific objective of solar corona and interplanetary research is the understanding of the various phenomena related to solar activities and their effects on the space environments of the Earth. Great progress has been made in the study of solar corona and interplanetary physics by the Chinese space physics community during the past years. This paper will give a brief report about the latest progress of the corona and interplanetary research in China during the years of 2010−2012. The paper can be divided into the following parts: solar corona and solar wind, CMEICME, magnetic reconnection, energetic particles, space plasma, space weather numerical modeling by 3D SIP-CESE MHD model, space weather prediction methods, and proposed missions. They constitute the abundant content of study for the complicated phenomena that originate from the solar corona, propagate in interplanetary space, and produce geomagnetic disturbances. All these progresses are acquired by the Chinese space physicists, either independently or through international collaborations.


Solar Corona and Solar Wind
It has already been established that the solar wind may originate at the edges of Active Regions (ARs), but the key questions of how frequently these outflows occur, and at which height the nascent solar wind originates have not yet been addressed.He et al. [1] study the occurrence rate of these intermittent outflows, the related plasma activities beneath in the low solar atmosphere, and the interplanetary counterparts of the nascent solar wind outflow.They use the observations from XRT (X-ray Telescope) /Hinode and TRACE to study the outflow patterns.
The occurrence frequency of the intermittent outflow is estimated by counting the occurrences of propagating intensity enhancements in height-time diagrams.The observations of SOT (Solar Optical Telescope)/Hinode and EIS (Extreme-ultraviolet Imaging Spectrometer)/Hinode are adopted to investigate the phenomena in the chromosphere associated with the coronal outflows.The ACE plasma and field in-situ measurements near Earth are used to study the interplanetary manifestations.They find that in one elongated coronal emission structure, referred to as strand, the plasma flows outward intermittently, about every 20 min.The flow speed sometimes exceeds 200 km•s −1 , which is indicative of rapid acceleration, and thus exceeds the coronal sound speed at low altitudes.The inferred flow speed of the soft-Xray-emitting plasma component seems a little higher than that of the Fe IX/X-emitting plasma component.
Chromospheric jets are found to occur at the root of the strand.Upflows in the chromosphere are also confirmed by blue-shifts of the He II line.The heliospheric plasma counterpart close to the Earth is found to be an intermediate-speed solar wind stream.
The AR edge may also deliver some plasmas to a fraction of the fast solar wind stream, most of which emanate from the neighboring Coronal Hole (CH).
The possible origin of the nascent solar wind in the chromosphere, the observed excessive outflow speed of over 200 km•s −1 in the lower corona, and the corresponding intermediate-speed solar wind stream in interplanetary space are all linked in their case study.
These phenomena from the low solar atmosphere to the heliosphere near Earth in combination shed new light on the solar wind formation process.These observational results will constrain future modeling of the solar winds originating close to an AR.
Coronal jets and mass ejections associated with erupting loops are two distinct and frequently observed types of transient upflows of plasma in CHs.
But the magnetic and spectroscopic properties of these events at the supergranular scale are not well known.He et al. [2] aim at studying in a polar hole the plasma and field characteristics of coronal jets and erupting loops of a supergranular size, for which they The magnetic evolution at the jet base is investigated, and the results indicate that the interaction between two flux tubes of opposite magnetic polarities as well as the squeezing of several tubes with identical polarities might be responsible for the jet initiation.They reveal for the first time the spectroscopic signatures of a supergranular-size erupting loop at its early stage, which consists of three steps.The first step is the onset, which is featured by a sudden brightening of one footpoint, as well as by the occurrence of blueshifts along almost its entire path.The second step is the initial expansion of the closed loop, which is estimated to move upward at a speed of about 20 km•s −1 , as derived from the Line-of-Sight (LOS) blueshift and the loop enlargement projected onto the plane of the sky.
In the third step, the loop's bright footpoint is apparently diminishing its intensity and enhancing its blueshift, which indicates that plasma upflow from the leg is filling the expanding loop volume.They conclude that in polar CHs, where the steady fast solar wind is known to emanate, there are also at least two possible ways of causing transient plasma outflows at supergranular scale.One is related to coronal jets guided by open field lines, the other to the eruption of closed loops, which is triggered by magnetic reconnection at their footpoints.

Persistent outflows have recently been detected
at the boundaries of some active regions.Although these outflows are suggested to be possible sources of the slow solar wind, the nature of these outflows is poorly understood.Through an analysis of an image sequence obtained by the X-Ray Telescope onboard the Hinode spacecraft, Guo et al. [3] found that quasiperiodic outflows are present in the boundary of an active region.The flows are observed to occur intermittently, often with a period of 5∼10 min.The pro-jected flow speed can reach more than 200 km•s −1 , while its distribution peaks around 50 km•s −1 .This sporadic high-speed outflow may play an important role in the mass loading process of the slow solar wind.
Their results may imply that the outflow of the slow solar wind in the boundary of the active region is intermittent and quasi-periodic in nature.
The origin of the solar wind is one of the most important unresolved problems in space and solar physics.Tian et al. [4] report the first spectroscopic signatures of the nascent fast solar wind on the basis of observations made by the EUV Imaging Spectrometer on Hinode in a polar coronal hole in which patches of blueshift are clearly present on Dopplergrams of coronal emission lines with a formation temperature of lg(T /K) > 5.8.The corresponding upflow is associated with open field lines in the coronal hole and seems to start in the solar transition region and becomes more prominent with increasing temperature.This temperature-dependent plasma outflow is interpreted as evidence of the nascent fast solar wind in the polar coronal hole.The patches with significant upflows are still isolated in the upper transition region but merge in the corona, in agreement with the scenario of solar wind outflow being guided by expanding magnetic funnels.Tian et al. [5] study horizontal supergranule-scale motions revealed by TRACE observation of the chromospheric emission, and investigate the coupling between the chromosphere and the underlying photosphere.A highly efficient feature-tracking technique called balltracking is applied for the first time to the image sequences obtained by TRACE (Transition Region and Coronal Explorer) in the passband of white light and the three ultraviolet passbands centered at 1700 Å, 1600 Å, and 1550 Å.The resulting velocity fields are spatially smoothed and temporally averaged in order to reveal horizontal supergranulescale motions that may exist at the emission heights of these passbands.They find indeed a high correlation between the horizontal velocities derived in the white-light and ultraviolet passbands.The horizontal velocities derived from the chromospheric and photospheric emission are comparable in magnitude.
The horizontal motions derived in the UV passbands might indicate the existence of a supergranule-scale magnetoconvection in the chromosphere, which may shed new light on the study of mass and energy supply to the corona and solar wind at the height of the chromosphere.However, it is also possible that the apparent motions reflect the chromospheric brightness evolution as produced by acoustic shocks which might be modulated by the photospheric granular motions in their excitation process, or advected partly by the supergranule-scale flow towards the network while propagating upward from the photosphere.To reach a firm conclusion, it is necessary to investigate the role of granular motions in the excitation of shocks through numerical modeling, and future high-cadence chromospheric magnetograms must be scrutinized.
The fluctuating magnetic helicity is considered as an important parameter in diagnosing the characteristic modes of solar wind turbulence.Among them is the Alfvén-cyclotron wave, which is probably responsible for the solar wind plasma heating, but has not yet been identified from the magnetic helicity of solar wind turbulence.He et al. [6] present the possible signatures of Alfvén-cyclotron waves in the distribution of magnetic helicity as a function of θ VB , which is the angle between the solar wind The work of Yao et al. [7] focuses on the relation between the electron density and the magnetic field strength in the solar wind, and aims to reveal its compressive nature and to determine the level of compressibility.For this purpose, they choose a period of quiet solar wind data obtained at 1 AU by the Cluster C1 satellite.The electron density is derived with a sampling time as high as 0. To determine the wave modes prevailing in solar wind turbulence at kinetic scales, He et al. [8] study the magnetic polarization of small-scale fluctuations in the plane perpendicular to the data sampling direction (namely, the solar wind flow direction, V SW ) and analyze its orientation with respect to the local background magnetic field B 0,local .As an example, they take only measurements made in an outward magnetic sector.When B 0,local is quasi-perpendicular to V SW , they find that the small-scale magneticfield fluctuations, which have periods from about 1 to 3 s and are extracted from a wavelet decomposition of the original time series, show a polarization ellipse with right-handed orientation.This is consistent with a positive reduced magnetic helicity, as previously reported.Moreover, for the first time they find that the major axis of the ellipse is perpendicular to B 0,local , a property that is characteristic of an oblique Alfvén wave rather than oblique whistler wave.For an oblique whistler wave, the major axis of the magnetic ellipse is expected to be aligned with B 0,local , thus indicating significant magnetic compressibility, and the polarization turns from right to left handedness as the wave propagation angle (θ kB ) increases toward 90 • .Therefore, they conclude that the observation of a right-handed polarization ellipse with orientation perpendicular to B 0,local seems to indicate that oblique Alfvén/ion-cyclotron waves rather than oblique fast-mode/whistler waves dominate in the "dissipation" range near the break of solar wind turbulence spectra occurring around the proton inertial length.
The basic characteristics of the global distribution for the corona plasma and magnetic field near 2.5 R s are analyzed by Shen et al. [9] with the statistical and numerical methods for 136 Carrington Rotations (CRs) covering four different phases of solar activity.By using the observational data and the velocity distribution model in the corona, the statistical average distribution of the magnetic field, density and the coronal mass outputs are analyzed for the four different phases.Then, a numerical study of the global distribution near 2.5 R s is made by solving a self-consistent MHD system.Finally, the solar wind speed at 1 AU is given by mapping the speed at 2.5 R s to that near 1 AU, and the comparison of the numerical results with the observational measurements and the simulation result of the Wang-Sheeley-Arge (WSA) model are made during more than 5 years.
The numerical results indicate that the global distributions on the source surface of 2.5 R s at different phases of solar activity could be used to predict the change of the solar wind in interplanetary space.
The temperature curve in the solar chromosphere has puzzled astronomers for a long time.Referring to the structure of supergranular cells, Song et al. [10] propose an inductive heating model.It mainly includes the following three steps.( 1 Song et al. [11]  Zhang et al. [12] have developed a computational software system to automate the process of identify- Zhang, Xia et al. [13]  and CHs implies that one should be careful in the modeling and interpretation of relevant observational data. It has been established that cold plasma condensations can form in a magnetic loop subject to localized heating of its footpoints.Xia et al. [14]  Using one-dimensional test particle simulations, the effect of a kinetic Alfvén wave on the Velocity Distribution Function (VDF) of protons in the collisionless solar wind is investigated.Li et al. [15] first use linear Vlasov theory to numerically obtain the property of a kinetic Alfvén wave (the wave propagates in the direction almost perpendicular to the background magnetic field).They then numerically simulate how the wave will shape the proton VDF.
It is found that Landau resonance may be able to generate two components in the initially Maxwellian proton VDF: a tenuous beam component along the direction of the background magnetic field and a core component.The streaming speed of the beam relative to the core proton component is from 1.2 to 1.3 Alfvén speed.
Chen et al. [16] present a novel method to evaluate the Alfvén speed and the magnetic field strength along the streamer plasma sheet in the outer corona.Li et al. [17] examine whether the flow tube along the edge of a coronal streamer supports standing shocks in the inner slow wind by solving an isothermal wind model in terms of the Lambert W function.
It is shown that solutions with standing shocks do exist and they exist in a broad area in the parameter space characterizing the wind temperature and flow tube.In particular, streamers with cusps located at a heliocentric distance 3.2 R s can readily support discontinuous slow winds with temperatures barely higher than 1 MK.
Both remote-sensing measurements using the Interplanetary Scintillation (IPS) technique and in-situ measurements by the Ulysses spacecraft show a bimodal structure for the solar wind at solar minimum conditions.At present it still remains to be addressed why the fast wind is fast and the slow wind is slow.
While a robust empirical correlation exists between the coronal expansion rate f c of the flow tubes and the speed v measured in-situ, a more detailed data analysis suggests that v depends on more than just f c .Li et al. [18] examine whether the non-radial shape of field lines, which naturally accompanies any nonradial expansion, could be an additional geometrical factor.They solve the transport equations incorporating the heating from turbulent Alfvén waves for an electron-proton solar wind along curved field lines given by an analytical magnetic field model, which is representative of a solar minimum corona.The field line shape is found to influence the solar wind parameters substantially, reducing the asymptotic speed by up to 130 km•s −1 or by 28% in relative terms, compared with the case where the field line curvature is neglected.This effect was interpreted in the general framework of energy addition in the solar wind: compared to the straight case, the field line curvature enhances the effective energy deposition to the subsonic flow, which results in a higher proton flux and a lower terminal proton speed.Their computations suggest that the field line curvature could be a geometrical factor which, in addition to the tube expansion, substantially influences the solar wind speed.Furthermore, although the field line curvature is unlikely to affect the polar fast solar wind at solar minima, it does help make the wind at low latitudes slow, which in turn helps better reproduce the Ulysses measurements.
Feng et al. [19] conduct a data survey searching for well-defined streamer wave events observed by the This is interpreted as an observational manifestation of the recovery process of the CME-disturbed corona.
It is also found that the Alfvénic critical point is at about 10 R s , where the flow speed, which equals the Alfvén speed, is about 200 km•s −1 .

CME-ICME
Zhao et al. [20] perform a detailed analysis of a CME An EIT wave, which typically appears as a diffuse brightening that propagates across the solar disk, is one of the major discoveries of the Extreme ultraviolet Imaging Telescope on board the SOHO.However, the physical nature of the so-called EIT wave continues to be debated.In order to understand the relationship between an EIT wave and its associated coronal wave front, Zhao et al. [21] investigate the mor- Based on time-dependent MHD simulation, Zhang et al. [22] investigate how physical features in the solar atmosphere affect the evolution of CMEs.
It is found that temperature and density play a crucial role in CME initiation.They argue that lower temperature facilitates the catastrophe's occurrence, and that the CMEs which initiate in low density could gain lower velocity.In their numerical experiment, by employing different values of β, the resulting eruptions of either slow or fast events may be obtained.
A three-dimensional (3-D), time-dependent, numerical Magnetohydrodynamic (MHD) model is used by Shen et al. [23] to investigate the evolution and in- time-marching method is used by Shen et al. [24] to in- side these regions, which can potentially drive largescale magnetospheric activities.Zuo et al. [25] take a case study to discuss the magnetospheric activities and the space weather effects caused by MCBLs.
Guo et al. [26] examine and compare the statisti- regions, are examined by Guo et al. [27] to demonstrate similarities and differences in the energy trans- whereas Joule heating, ring current and total output energy display no distinguishable differences.The means of electron precipitation are significantly different for both classes of events.However, ion precipitation exhibits no distinguishable differences.The energy efficiency bears no distinguishable difference between these two classes of events.Ionospheric processes account for the vast majority of the energy, with the ring current only being from 12% to 14% of the total.Moreover, the energy partitioning for both classes of events is similar.
Wang et al. [28] present an automated system, How to properly understand CMEs viewed in white light coronagraphs is crucial to many relative researches in solar and space physics.The issue is particularly addressed by Wang et al. [29]  The second paper by Chen et al. [30] reports sta- Shen et al. [31] study the kinematic evolution of Ten CME events viewed by the STEREO twin spacecraft are analyzed by Gui et al. [32] to study The transition of the magnetic field from the ambient magnetic field to the ejecta in the sheath downstream of a CME-driven shock is analyzed by Liu et al. [33] in detail.The field rotation in the sheath occurs in a two-layer structure.In the first layer, Layer At which height is a prominence inclined to be unstable, or where is the most probable critical height for the prominence destabilization?This question is statistically studied by Liu, Wang et al. [34]  CMEs, which is a long-standing puzzle.In order to solve the puzzle, Zhang et al. [35]  The Thomson scattering of these events is calculated when they are assumed to be observed as limb and halo events, respectively.It is found that the whitelight intensity of many slow CMEs becomes remarkably reduced when they turn from being viewed as a limb event to being viewed as a halo event.When the intensity is below the background solar wind fluctuation, it is assumed that they would be missed by coronagraphs.The average velocity of "detectable" halo CMEs is about 922 km•s −1 , very close to the observed value.This also indicates that wider events are more likely to be recorded.The results soundly suggest that the higher average velocity of halo CMEs is due to that a majority of slow events and some of narrow fast events carrying less material are so faint that they are blended with the solar wind fluctuations, and therefore can not observed.
Kinematic properties of CMEs suffer from projection effects, and it is expected that the real velocity should be larger and the real angular width should be smaller than the apparent values.Several attempts have been taken to correct the projection effects, which however led to an inflated average velocity probably due to the biased choice of CME events.In order to estimate the overall influence of the projection effects on the kinematic properties of the CMEs, Wu and Chen [36] perform a forward modeling of real EUV Imaging Telescope (EIT) waves are a wavelike phenomenon propagating outward from the coronal mass ejection source region, with expanding dimmings following behind.Chen et al. [37]  The nature of EIT wave is still elusive, with the debate on-going between fast-mode wave model and non-wave model.In order to distinguish between these models, Yang and Chen [38] investigate the re- Chen et al. [39] report a spectroscopic analysis of Chen and Wu [40] suggest that "EIT waves" are the apparent propagation of the plasma compression due to successive stretching of the magnetic field lines The data from SOHO/EIT and SOHO/LASCO observations are used by Liu et al. [41]  the white light coronagraph data, Chen et al. [42] show that the streamer wave has a period of about 1 h, a wavelength varying from 2 to 4 solar radii, an amplitude of about a few tens of solar radii, and a propagating phase speed in the range from 300 to 500 km•s −1 .They also find that there is a tendency With a survey through the LASCO data from 1996 to 2009, Song et al. [43] present 11 events with plasma blobs flowing outwards sequentially along a bright coronal ray in the wake of a coronal mass ejection.The ray is believed to be associated with the current-sheet structure that formed as a result of solar eruption, and the blobs are products of magnetic reconnection occurring along the current sheet.The ray morphology and blob dynamics are investigated statistically.It is found that the apparent angular widths of the rays at a fixed time vary in a range from 2.1 • to 6.6 • (from 2.0 • to 4.4 • ) with an average of 3.5 • (2.9 • ) at 3 R s (4 R s ), respectively, and the observed durations of the events vary from 12 h to a few days with an average of 27 h.It is also found, based on the analysis of blob motions, that 58% (26) of the blobs are accelerated, 20% (9) are decelerated, and 22% (10) moved with a nearly constant speed.Comparing the dynamics of their blobs and those that are observed above the tip of a helmet streamer, they find that the speeds and accelerations of the blobs in these two cases differ significantly.It is suggested that these differences of the blob dynamics stem from the associated magnetic reconnection involving different magnetic field configurations and triggering processes.

Magnetic Reconnection in Interplanetary Space
Wang et al. [44] report in situ observation of ener- Xu et al. [45] identify two Petschek-like exhaust events within the interiors of the second and third flux ropes, respectively.In the first event, WIND and ACE detected an exhaust at the same side from the reconnection site, which is associated with a large-scale bifurcated current sheet with a spatial width of about 10 000 ion inertial lengths and the magnetic shear was 155 • .In the second event, the two spacecraft observed the oppositely directed exhausts from a single reconnection X line.The exhausts are also related to The interaction between interplanetary smallscale magnetic flux ropes and the magnetic field in the ambient solar wind is an important topic in the understanding of the evolution of magnetic structures in the heliosphere.Through a survey of 125 previously reported small flux ropes from 1995 to 2005, Tian et al. [46] find that 44 of them reveal clear signa- Two-dimensional particle-in-cell simulations are performed by Huang et al. [48] to investigate electron dynamics in antiparallel and guide field (in the pres- and the out-of-plane magnetic field are investigated by Lu et al. [49] with both two-dimensional particle-incell simulations and Cluster observations.They conclude that the electron density depletions are formed because of the magnetic mirror, and they are outside the peaks of the out-of-plane magnetic field.Such a theoretical prediction is confirmed by both simulations and observations.Two-dimensional (2-D) particle-in-cell simulations are performed by Lu et al. [50] to investigate the structures of the out-of-plane magnetic field in magnetic island, which is produced during anti-parallel collisionless magnetic reconnection.Regular structures with alternate positive and negative values of the out-of-plane magnetic field along the x direction are formed in magnetic island.The generation mechanism of such structures is also proposed in their paper, which is due to the Weibel instability excited by the temperature anisotropy in magnetic island.
Two-dimensional particle-in-cell simulations are performed by Lu et al. [51] to investigate the formation of electron density depletions in collisionless mag- simulations are performed by Huang et al. [52] to investigate the evolution of the Electron Current Sheet (ECS) in guide field reconnection.The ECS is formed by electrons accelerated by the inductive electric field in the vicinity of the X line, which is then extended along the x direction due to the imbalance between the electric field force and Ampere force.The tearing instability is unstable when the ECS becomes sufficiently long and thin, and several seed islands are formed in the ECS.These tiny islands may coalesce and form a larger secondary island in the center of the diffusion region.
The evolutionary process of magnetic reconnection under solar coronal conditions is investigated by Zhang et al. [53] with their recently developed 2.

Energetic Particles
Recently, Tan and coworkers study the 2001 September 24 Solar Energetic Particle (SEP) event observed by the WIND spacecraft at 1 AU and found that there is a counter-streaming particle beam with a deep depression of flux at 90 • pitch angle during the beginning of the event.They suggested that it is a result of a reflecting boundary at some distance out-side 1 AU.While this scenario could be true under some specific configuration of an interplanetary magnetic field, Qin et al. [54] offer another possible ex- A model of SEP propagation in the threedimensional Parker interplanetary magnetic field is calculated numerically by He et al. [55] .They study the effects of the different aspects of particle source on the solar surface, which include the source location, coverage of latitude and longitude, and spatial distribution of source particle intensity, on propagation of SEPs with both parallel and perpendicular diffusion.They compute the particle flux and anisotropy profiles at different observation locations in the heliosphere.From their calculations, they find that the observation location relative to the latitudinal and longitudinal coverage of particle source has the strongest effects on particle flux and anisotropy profiles observed by a spacecraft.When a spacecraft is directly connected to the solar sources by the interplanetary magnetic field lines, the observed particle fluxes are larger than when the spacecraft is not directly connected.They focus on the situations when a spacecraft is not connected to the particle sources on the solar surface.They find that when the magnetic footpoint of the spacecraft is farther away from the source, the observed particle flux is smaller and its onset and maximum intensity occur later.When the particle source covers a larger range of latitude and longitude, the observed particle flux is larger and appears earlier.There is east-west azimuthal asymmetry in SEP profiles even when the source distribution is east-west symmetric.However, the detail of particle spatial distribution inside the source does not affect the profile of the SEP flux very much.When the magnetic footpoint of the spacecraft is significantly far away from the particle source, the anisotropy of particles in the early stage of an SEP event points toward the Sun, which indicates that the first arriving particles come from outside of the observer through perpendicular diffusion at large radial distances.
To obtain the mean free path of SEPs for a solar event, one usually has to fit time profiles of both flux and anisotropy from spacecraft observations to numerical simulations of SEPs' transport processes.
This method can be called a simulation method.
But a reasonably good fitting needs a lot of simulations, which demand a large amount of calculation resources.Sometimes, it is necessary to find an easy way to obtain the mean free path of SEPs quickly, for example, in space weather practice.Recently, Shalchi et al. provided an approximate analytical formula of SEPs' anisotropy time profile as a function of particles' mean free path for impulsive events.He and Qin [56] determine SEPs' mean free path by fitting the anisotropy time profiles from Shalchi et al.'s analytical formula to spacecraft observations.This new method can be called an analytical method.In addition, they obtain SEPs' mean free path with the traditional simulation methods.Finally, they compare the mean free path obtained with the simulation method to that of the analytical method to show that the analytical method, with some minor modifications, can give a good, quick approximation of SEPs' mean free path for impulsive events.
The analytical nonlinear theory of magnetic field line random walk predicts the existence of nondiffusive transport for certain forms of the turbulence spectrum.Shalchi and Qin [57] use computer simulations to test these predictions made for wellestablished one-and two-dimensional models of magnetic field fluctuations.For the first time it is shown by using simulations, that for a whole family of spectra a non-diffusive behavior of field line wandering can be found.obliquities is investigated by Zuo et al. [58] based on the FTE.They solve the FTE by using a stochastic approach.The shock acceleration leads to a twocomponent energy spectrum.The low-energy component of the spectrum is made up of particles that interact with shock one to a few times.For these particles, the pitch angle distribution is highly anisotropic, and the energy spectrum is variable depending on the momentum and pitch angle of injected particles.
At high energies, the spectrum approaches a power law consistent with the standard Diffusive Shock Acceleration (DSA) theory.For a parallel shock, the high-energy component of the power-law spectrum, with the spectral index being the same as the prediction of DSA theory, starts just a few times the injection speed.For an oblique or quasi-perpendicular shock, the high-energy component of the spectrum exhibits a double power-law distribution: a harder power-law spectrum followed by another power-law spectrum with a slope the same as the spectral index of DSA.The shock acceleration will eventually go into the DSA regime at higher energies even if the anisotropy is not small.The intensity of the energy spectrum given by the FTE, in the high-energy range where particles get efficient acceleration in the DSA regime, is different from that given by the stan-dard DSA theory for the same injection source.They define the injection efficiency η as the ratio between them.For a parallel shock, the injection efficiency is less than 1, but for an oblique shock or a quasiperpendicular shock it could be greater.
The issue of the influence of Coronal Holes (CHs) on CMEs in causing SEP events is revisited by Shen et al [59] .It is a continuation and extension of their  [60] from SOHO/LASCO observations.Then, they investigate the relationships between the kinematic properties of these CMEs and the characteristic times of the intensity-time profile of their accompanied SEP events observed at 1 AU.These characteristic times of SEP are (1) the onset time from the accompanying CME eruption at the Sun to the SEP arrival at 1 AU, (2) the rise time from the SEP onset to the time when the SEP intensity is one-half of peak intensity, and the duration over which the SEP intensity is within a factor of two of the peak intensity.It is found that the onset time has neither significant correlation with the radial speed nor with the angular width of the accompanying CME.For events that are poorly connected to the Earth, the SEP rise time and duration have no significant correlation with the radial speed and angular width of the associated CMEs.However, for events that are magnetically well connected to the Earth, the SEP rise time and duration have significantly positive correlations with the radial speed and angular width of the associated CMEs.This indicates that a CME event with wider angular width and higher speed may more easily drive a strong and wide shock near the Earth-connected interplanetary magnetic field lines, may trap and accelerate particles for a longer time, and may lead to longer rise time and duration of the ensuing SEP event.

Space Plasma
A multidimensional electron phase-space hole (electron hole) is considered to be unstable to the transverse instability.Wu et al. [61]  A multi-dimensional electron phase-space hole (electron hole) is considered to be unstable to the transverse instability.Wu et al. [62] perform twodimensional Particle-in-Cell (PIC) simulations to study the evolutions of electron holes in weakly magnetized plasma (Ω e < ω pe , where Ω e and ω pe are the electron gyrofrequency and plasma frequency, respectively), and the effects of perpendicular thermal velocities on the transverse instability are investigated.
The transverse instability can cause decay of the electron holes.They find that with the increasing perpendicular thermal velocity tending to stabilize the transverse instability, the corresponding wave numbers decrease.
Observations have shown that electron phasespace holes (electron holes) possess regular magnetic structures.Wu et al. [63]  parts, Yang et al. [64] investigate the ion distributions A test particle code is employed by Gao et al. [66] to explore the dynamics of charged particles and perpendicular diffusion in turbulent magnetic field, where a three-dimensional (3-D) isotropic turbulence model is used.The obtained perpendicular diffusion at different particle energies is compared with that of the Nonlinear Guiding Center (NLGC) theory.It is found that the NLGC theory is consistent with test particle simulations when the particle energies are small.However, the difference between the NLGC theory and test particle simulations tends to increase when the particle energy is sufficiently large, and the threshold is related to the turbulence bendover length.In the NLGC theory, the gyrocenter of a charged particle is assumed to follow the magnetic field line.Therefore, when the particle has sufficiently large energy, its gyroradius will be larger than the turbulence bend-over length.Then the particle can cross the magnetic field lines, and the difference between the test particle simulations and NLGC theory occurs.
Wang et al. [67]  Satellite observations have revealed that superthermal electrons in space plasma generally possess a power law distribution.Lu et al. [68]

Space Weather Numerical Modeling by 3-D SIP-CESE MHD Model
Feng et al. [69] explore the application of a six- A hybrid 3-D MHD model for solar wind study is proposed by Feng et al. [70] with combined grid sys- Feng et al. [71] carry out the Adaptive Mesh Refinement (AMR) implementation of the SIP-CESE MHD model using a six-component grid system.By transforming the governing MHD equations from the physical space (x, y, z) to the computational space (ξ, η, ζ) while retaining the form of conservation, the SIP-AMR-CESE MHD model is implemented in the reference coordinates with the aid of the parallel AMR package PARAMESH available at the website of http://sourceforge.net/projects/paramesh/.In the meantime, the same volumetric heating source terms as in Feng et al. [69] are also included.The simulated solar-wind background of different solaractivity phases show overall good agreements in the solar corona and in interplanetary space with these multiple-spacecraft observations.
Zhou et al. [72] present the evolution of the Sun- Jiang et al. [73] present new extensions of the Jiang et al. [74] present a new implementation of the MHD relaxation method for reconstruction of the nearly force-free coronal magnetic field from validate the method and confirm its capability for future practical application, with observed magnetograms as inputs.The same method has been further improved [75] recently.
The observations both near the Sun and in the heliosphere during the activity minimum between solar cycles 23 and 24 exhibit different phenomena from those typical of the previous solar minima.Yang et al. [76] have chosen Carrington Yang et al. [77] conduct simulations using the In summary, the SIP-CESE MHD model devel-oped by Feng and his colleagues [69−77] has the following merits.
(1) The new implementation of volumetric heating source term taking the topological effect of magnetic field with the expansion factor (f s ) and the angular distance (θ b ) into consideration, to some extent, can effectively distinguish the high-speed solar wind from the low-speed solar wind.
( (4) The solution points in SIP-CESE MHD model [74] are explicitly given on the mesh nodes, (8) It should be noted that the same CESE solver can apply to any coordinate system (such as Cartesian, spherical, cylindrical coordinates and any other curvilinear coordinates) with only the difference of the coordinate transformation, and consequently the solver is highly independent of the grid system.
(9) Based on the CESE MHD model, the new implementation of the MHD relaxation method [73−75] for reconstruction of coronal magnetic field from a photospheric vector magnetogram will open a new way for the study of solar active region with the help of HMI/SDO or MDI/SOHO observations.

Space Weather Prediction Methods
Shen et al. [78] develop an improved model to build A 1D-HD shock propagation model is established by Zhang et al. [79] to predict the arrival time of interplanetary shocks at 1 AU.Applying this model to 68 solar events during the period of February 1997 to October 2000, it is found that their model could be practically equivalent to the STOA, ISPM and HAFv.2 models in forecasting the shock arrival time.The absolute error in the transit time from their model is not larger than those of the other three models for the same sample events.Also, the prediction test shows that the relative error of their model is 10% for 31% of all events, 30% for 75%, and 50% for 84%, which is comparable to the relative errors of the other models.These results might demonstrate a potential capability of their model in terms of real-time forecasting.
Using 141 CME-interplanetary shock (CME-IPS) events and f 0 F 2 from eight ionosonde stations from January 2000 to September 2005, from the statistical results, Li et al. [80] find that there is a "same side-opposite side effect" in ionospheric negative storms, i.e., a large portion of ionospheric nega- The SPORT spacecraft will also be equipped with a set of optical and in situ measurement instruments such as a EUV solar telescope, a solar wind ion instrument, an energetic particle detector, a magnetometer, a wave detector and a solar radio burst spectrometer.
use observations from XRT, EIS and SOT on Hinode as well as EUVI on Solar Terrestrial Relations Observatory (STEREO).The open magnetic field structures related to the coronal jets are obtained by magnetic field extrapolation into the corona from SOT magnetograms.Furthermore, they use the EIS ob-servations to analyze ultraviolet line intensities and Doppler shifts in association with the erupting loops.They find that the coronal jet plasma is indeed ejected along open field lines, thus confirming the conjecture of jet formation in an open magnetic environment.
velocity and local mean magnetic field.They use magnetic field data from the STEREO spacecraft to calculate the θ VB distribution of the normalized reduced fluctuating magnetic helicity σ m .They find a dominant negative σ m for 1 s< p < 4 s (p is time period) and for θ VB < 30 • in the solar wind outward magnetic sector, and a dominant positive σ m for 0.4 s < p <4 s and for θ VB > 150 • in the solar wind inward magnetic sector.These features of σ m appearing around the Doppler-shifted ion-cyclotron frequencies may be consistent with the existence of Alfvén-cyclotron waves among the outward propa-gating fluctuations.Moreover, right-handed polarized waves at larger propagation angles, which might be kinetic Alfvén waves or whistler waves, have also been identified on the basis of the σ m features in the angular range 40 • < θ VB < 140 • .Their findings suggest that Alfvén-cyclotron waves (together with other wave modes) play a prominent role in turbulence cascading and plasma heating of the solar wind.
2 s from the spacecraft-potential measurements made by the electric field and waves instrument.They use the wavelet cross-coherence method to analyze the correlation between the electron density and the magnetic field strength on various scales.They find a dominant anti-correlation between them at different timescales ranging from 1000 s down to 10 s, a result which has never been reported before.This may indicate the existence of Pressure-Balanced Structures (PBSs) with different sizes in the solar wind.The small (mini) PBSs appear to be embedded in the large PBSs, without affecting the pressure balance between the large structures.Thus, a nesting of these possible multi-scale PBSs is found.Moreover, they find for the first time that the relative fluctuation spectra of both the electron number density and the magnetic field strength look almost the same in the range from 0.01 Hz to 2.5 Hz, implying a similar cascading for these two types of fluctuations.Probable formation mechanisms for the multi-scale possible PBSs are discussed.The results of their work are believed to be helpful for understanding the compressive nature of solar wind turbulence as well as the connections between the solar wind streams and their coronal sources.
) A small-scale dynamo exists in the supergranulation and produces alternating small-scale magnetic fluxes.(2) The supergranular flow distributes these small-scale fluxes according to a regular pattern.(3) A skin effect occurs in the alternating and regularly-distributed magnetic fields.The induced current is concentrated near the transition region and heats it by resistive dissipation.
measure the differential rotation of strong magnetic flux during solar cycles 21−23 with the method of wavelet transforms.The cycleaveraged synodic rotation rate of strong magnetic flux is found to be written as ω = 13.47 − 2.58 sin 2 θ or ω = 13.45 − 2.06 sin 2 θ − 1.37 sin 4 θ, where θ is the latitude.It agrees well with the results derived from sunspots.A northsouth asymmetry of the rotation rate is found at high latitudes (28 • < θ < 40 • ).The strong flux in the southern hemisphere rotates faster than that in the northern hemisphere by 0.2 • per day.The asymmetry continued for cycles 21−23 and may be a secular property.
ing solar Active Regions (ARs) and quantifying their physical properties based on high-resolution synoptic magnetograms constructed from Michelson Doppler Imager (MDI) images on board the Solar and Heliospheric Observatory (SOHO) spacecraft from 1996 to 2008.The system, based on morphological analysis and intensity thresholding, has four functional modules: (1) intensity segmentation to obtain kernel pixels, (2) a morphological opening operation to erase small kernels, which effectively remove ephemeral regions and magnetic fragments in decayed ARs, (3) region growing to extend kernels to full AR size, and (4) the morphological closing operation to merge/group regions with a small spatial gap.They calculate the basic physical parameters of the 1730 ARs identified by the auto system.The mean and maximum magnetic flux of individual ARs are 1.67 × 10 22 Mx and 1.97 × 10 23 Mx, while that per Carrington rotation are 1.83 × 10 23 Mx and 6.96 × 10 23 Mx, respectively.The frequency distributions of ARs with respect to both area size and magnetic flux follow a log-normal function.However, when they decrease the detection thresholds and thus increase the number of detected ARs, the frequency distribution largely follows a power-law function.They also find that the equatorward drifting motion of the AR bands with solar cycle can be described by a linear function superposed with intermittent reverse driftings.The average drifting speed over one solar cycle is 1.83 • ± 0.04 • per year or 0.708 ± 0.015 m•s −1 .
The method is based on recent observations of streamer waves, which are regarded as the fast kink body mode carried by the plasma sheet structure and generated upon the impact of a fast Coronal Mass Ejection (CME) on a nearby streamer.The mode propagates outward with a phase speed consisting of two components.One is the phase speed of the mode in the plasma rest frame and the other is the speed of the solar wind streaming along the plasma sheet.The former can be well represented by the Alfvén speed outside the plasma sheet, according to a linear wave dispersion analysis with a simplified slab model of magnetized plasmas.The radial profiles of the Alfvén speed can be deduced with constraints put on the speed of the solar wind, which is done by making use of the measurements of streamer blobs flowing passively in the wind.The radial profiles of the strength of the coronal magnetic field can be depicted once the electron density distribution is specified, and this is done by inverting the observed polarized brightness data.Comparing the diagnostic results corresponding to the first wave trough and the following crest, they find that both the Alfvén speed and magnetic field strength at a fixed distance decline with time.This is suggestive of the recovering process of the CME-disturbed corona.
LASCO on-board SOHO throughout Solar Cycle 23.As a result, eight candidate events are found and presented.They compare different events and find that in most of them the driving CMEs' ejecta are characterized by a high speed and a wide angular span, and the CME-streamer interactions occur generally along the flank of the streamer structure at an altitude no higher than the bottom of the field of view of LASCO C2.In addition, all front-side CMEs have accompanying flares.These common observational features shed light on the excitation conditions of streamer wave events.They also conduct a further analysis on one specific streamer wave event on 5 June 2003.The heliocentric distances of four wave troughs/crests at various exposure times are determined; they are then used to deduce the wave properties like period, wavelength, and phase speeds.It is found that both the period and wavelength increase gradually with the wave propagation along the streamer plasma sheet, and the phase speed of the preceding wave is generally faster than that of the trailing ones.The associated coronal seismological study yields the radial profiles of the Alfvén speed and magnetic field strength in the region surrounding the streamer plasma sheet.Both quantities show a general declining trend with time.

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January 2008.The combination of the SOHO and twin STEREO spacecraft provides three-point observations of this CME.They track the CME in imaging observations and compare its morphology and kinematics viewed from different vantage points.The shape, angular width, distance, velocity, and acceleration of the CME front are different in the observations of these spacecraft.They also compare the efficiency of several methods, which convert the elongation angles of the CME front in images to radial distances.The results of their kinematic analysis demonstrate that this CME experiences a rapid acceleration at the early stage, which corresponds to the flash phase of the associated solar flare in time.Then, at a height of about 3.7 solar radius, the CME reaches a velocity of 790 km•s −1 and propagates outward without an obvious deceleration.Because of its propagation direction away from the observers, the CME is not detected in situ by either ACE or STEREO.
phology and kinematics of the CME-EIT wave event that occurred on 17 January 2010.Using the observations of the SECCHI EUVI, COR1 and COR2 instruments on board the STEREO-B, they track the shape and movements of the CME fronts along different radial directions to a distance of about 15 solar radii (R s ); for the EIT wave, they determine the propagation of the wave front on the solar surface along different propagating paths.The relation between the EIT wave speed, the CME speed and the local fastmode characteristic speed is also investigated.Their results demonstrate that the propagation of the CME front is much faster than that of the EIT wave on the solar surface, and that both the CME front and the EIT wave propagate faster than the fast-mode speed in their local environments.Specifically, they show a significant positive correlation between the EIT wave speed and the local fast-mode wave speed in the propagation paths of the EIT wave.Their findings support that the EIT wave under study is a fast-mode magnetohydrodynamic wave.
of two CMEs in the nonhomogeneous ambient solar wind.The background solar wind is constructed on the basis of the self-consistent source surface with observed line of sight of magnetic field and density from the source surface of 2.5 R s to Earth's orbit (215 R s ) and beyond.The two successive CMEs occurring on 28 March 2001 and forming of a multiple magnetic cloud in interplanetary space are chosen as a test case, in which they are simulated by means of a two high-density, high-velocity and high temperature magnetized plasma blobs, and are successively ejected into the nonhomogeneous background solar wind medium along different initial launch directions.The dynamical propagation and interaction of the two CMEs between 2.5 R s and 220 R s are investigated.Their simulation results show that, although the two CMEs are separated by 10 h, the second CME is able to overtake the first one and cause compound interactions and an obvious acceleration of the shock.At the L 1 point near Earth the two resultant magnetic clouds in their simulation are consistent with the observations by ACE.In this validation study they find that this 3-D MHD model, with the self-consistent source surface as the initial boundary condition and the magnetized plasma blob as the CME model, is able to reproduce and explain some of the general characters of the multiple magnetic clouds observed by satellites.A three-dimensional (3-D) time-dependent, numerical MHD model with asynchronous and parallel vestigate the propagation of CMEs in the nonhomogeneous background solar wind flow.The background solar wind is constructed based on the self-consistent source surface with observed line-of-sight of magnetic field and density from the source surface of 2.5 R s to the Earth's orbit (215 R s ) and beyond.The CMEs are simulated by means of a very simple flux rope model: a high-density, high-velocity, and high temperature magnetized plasma blob is superimposed on a steady state background solar wind with an initial launch direction.The dynamical interaction of a CME with the background solar wind flow between 2.5 R s and 220 R s is investigated.The evolution of the physical parameters at the cobpoint, which is located at the shock front region magnetically connected to ACE spacecraft, is also investigated.They choose the well-defined halo-CME event of 4−6 April 2000 as a test case.In this validation study they find that this 3-D MHD model, with the asynchronous and parallel time-marching method, the self-consistent source surface as initial boundary conditions, and the simple flux rope as CME model, provide a relatively satisfactory comparison with the ACE spacecraft observations at the L 1 point.On 9 November 2004, the WIND spacecraft detected a Magnetic Cloud Boundary Layer (MCBL) during the interval from 19:07 UT to 20:30 UT.Within the MCBL, there is intense southward magnetic field and the dynamic pressure is rather high, which makes it much geoeffective.Twenty-three minutes later, the MCBL arrived at the magnetopause.An intense geomagnetic storm main phase was driven by the sustaining strong southward magnetic field within the MCBL.During the passage of the MCBL, a typical magnetospheric substorm was triggered.The substorm onset was synthetically identified by the aurora breakup, magnetic dipolarization, dispersionless particle injection, Pi2 pulsation and the polar bay onset.The substorm triggering is related to the special magnetic and plasma structure within the MCBL.The MCBL accompanying adjacent sheath region formed a dynamic pressure enhancement region, which strongly compressed the magnetosphere and even pushed the magnetopause into the geosynchronous orbit so that two dayside spacecraft GOES-10 and GOES-12 were directly exposed in the magnetosheath for a long interval during the passage of the MCBL.In terms of Shue et al. (1998) model, the closest subsolar standoff distance even reached 5.1 R e during the passage of the MCBL.It can be inferred that the strong dynamic pressure and the strong discontinuities within the MCBL determine the intense compression effect.In addition, a very intense Geomagnetically Induced Current (GIC) event was directly caused by the MCBL.Similar to this case, majority of MCBLs are dynamic pressure enhancement regions, and there are strong southward magnetic field and several strong discontinuities in- properties of Interplanetary Coronal Mass Ejections (ICMEs) and their sheath regions in the near-Earth space, mainly focusing on the distributions of various physical parameters and their geoefficiency.The 53 events studied are a subset of events responsible for intense (Dst = −100 nT) geomagnetic storms during the time period from 1996 to 2005.These events all fall into the single-type category in which each of the geomagnetic storms is caused by a wellisolated single ICME, free of the complexity of the interaction of multiple ICMEs.For both sheaths and ICMEs, they find that the distributions of the magnetic field strength, the solar-wind speed, the density, the proton temperature, the dynamic pressure, the plasma beta, and the Alfvén Mach number are approximately lognormal, while those of the B z component and the y component of the electric field are approximately Gaussian.On the average, the magnetic field strengths, the B z components, the speeds, the densities, the proton temperatures, the dynamic pressures, the plasma betas and the Mach numbers for the sheaths are 15%, 80%, 4%, 60%, 70%, 62%, 67% and 30% higher than the corresponding values for ICMEs, respectively, whereas the y component of the electric field for the sheaths is almost 1 s of that for ICMEs.The two structures have almost equal en-ergy transfer efficiency and comparable Newell functions, whereas they show statistically meaningful differences in the dayside reconnection rate, according to the Borovsky function.The interaction of the solar wind and Earth's magnetosphere is complex, and the phenomenology of the interaction is very different for ICMEs compared to sheath regions.A total of 71 intense (Dst −100 nT) geomagnetic storm events in 1996−2006, of which 51 are driven by ICMEs and 20 by sheath fer.Using superposed epoch analysis, the evolution of solar wind energy input and dissipation is investigated.The solar wind-magnetosphere coupling functions and geomagnetic indices show a more gradual increase and recovery during the ICME-driven storms than they do during the sheath-driven storms.However, the sheath-driven storms have larger peak values.In general, solar wind energy input (the epsilon parameter) and dissipation show similar trends as the coupling functions.The trends of ion precipitation and the ratio of ion precipitation to the total (ion and electron) are quite different for both classes of events.There are more precipitating ions during the peak of sheath-driven storms.However, a quantitative assessment of the relative importance of the different energy dissipation branches shows that the means of input energy and auroral precipitation are significantly different for both classes of events, which has the capability to catch and track solar limb prominences based on observations from the Extreme-Ultraviolet (EUV) 304 Å passband.The characteristic parameters and their evolution, including height, position angle, area, length and brightness, are obtained without manual interventions.By applying the system to the STEREO-B/SECCHI/EUVI 304 Å data from April 2007 to October 2009, they obtain a total of 9477 well-tracked prominences and a catalog of these events available online.A detailed analysis of these prominences suggests that the system has a rather good performance.They have obtained several interesting statistical results based on the catalog.Most prominences appear below the latitude of 60 • and at the height of about 26 Mm above the solar surface.Most of them are quite stable during the period they are tracked.Nevertheless, some prominences have an upward speed of more than 100 km•s −1 , and some others show significant downward and/or azimuthal speeds.There are strong correlations among the brightness, area, and height.The expansion of a prominence is probably one major cause of its fading during the rising or erupting process.

the 8
October 2007 CME in the corona based on observations from SECCHI onboard satellite B of STEREO.The observational results show that this CME obviously deflects to a lower latitude region of about 30 • at the beginning.After this, the CME propagates radially.They also analyze the influence of the background magnetic field on the deflection of this CME.They find that the deflection of this CME at an early stage may be caused by a nonuniform distribution of the background magnetic-field energy density and that the CME tends to propagate to the region with lower magnetic-energy density.In addition, they find that the velocity profile of this gradual CME shows multiphased evolution during its propagation in the COR1-B FOV.The CME velocity first remains constant (23.1 km•s −1 ).Then it accelerates continuously with a positive acceleration of 7.6 m•s −2 .
the deflections of CMEs during their propagation in the corona.Based on the three-dimensional information of the CMEs derived by the Graduated Cylindrical Shell (GCS) model (Thernisien, Howard and Vourlidas in Astrophys.J., 2006, 652, 1305), it is found that the propagation directions of eight CMEs changed.By applying the theoretical method proposed by Shen et al. (Solar Phys., 2011, 269, 389) to all the CMEs, they find that the deflections are consistent, in strength and direction, with the gradient of the magnetic energy density.There is a positive correlation between the deflection rate and the strength of the magnetic energy density gradient and a weak anti-correlation between the deflection rate and the CME speed.Their results suggest that the deflections of CMEs are mainly controlled by the background magnetic field and can be quantitatively described by the Magnetic Energy Density Gradient (MEDG) model.

1 ,
figuration of the CME near the Sun.They use a 3-D MHD simulation code, the Space Weather Modeling Framework (SWMF) to simulate the propagation of CMEs and the shock driven by it.Close to the Sun, Layer 2 dominates the width of the sheath, diminishing its importance as the sheath evolves away from the Sun, consistent with observations at 1 AU.
first investigate the observed properties of 31 limb CMEs that clearly display loopshaped frontal loops.The observational results show a strong tendency that slower CMEs are weaker in white-light intensity.Then, they perform a Monte Carlo simulation of 20 000 artificial limb CMEs that have an average velocity of about 523 km•s −1 .

1 and 42 . 7 •
distributions of CME properties, such as the velocity, the angular width and the latitude, by requiring their projected distributions to best match observations.Such a matching is conducted by Monte Carlo simulations.According to the derived real distributions, they found that (1) the average real velocity of all non-full-halo CMEs is about 514 km•s −1 , and the average real angular width is about 33 • , in contrast to the corresponding apparent values of 418 km•s −in observations; (2) For the CMEs with the angular width in the range from 20 • to 120 • , the average real velocity is 510 km•s −1 and the average real angular width is 43.4 • , in contrast to the corresponding apparent values of 392 km•s −1 and 52 • in observations.
present a spectroscopic study of an EIT wave/dimming event observed by the Hinode/Extreme-ultraviolet Imaging Spectrometer.Although the identification of the wave front is somewhat affected by the pre-existing loop structures, the expanding dimming is well defined.They investigate the line intensity, width and Doppler velocity for four EUV lines.In addition to the significant blueshift implying plasma outflows in the dimming region as revealed in previous studies, they find that the widths of all four spectral lines increase at the outer edge of the dimmings.They illustrate that this feature can be well explained by the field line stretching model, which claims that EIT waves are apparently moving brightenings that are generated by the successive stretching of the closed field lines.
between the EIT wave velocity and the local magnetic field in the corona.It is found that the two parameters show significant negative correlation in most of the EIT wave fronts, i.e., the EIT wave propagates more slowly in the regions of stronger magnetic field.Such a result poses a big challenge to the fast-mode wave model, which would predict a strong positive correlation between the two parameters.However, it is demonstrated that such a result can be explained by the fieldline stretching model, i.e., that "EIT waves" are the propagation of apparent brightenings, which are generated by successive stretching of closed magnetic field lines pushed by the erupting flux rope during CMEs.
an EUV Imaging Telescope (EIT) wave event that occurred in active region 11081 on 12 June 2010 and was associated with an M2.0 class flare.The wave propagated nearly circularly.The southeastern part of the wave front passed over an upflow region near a magnetic bipole.Using EUV Imaging Spectrometer raster observations for this region, they study the properties of plasma dynamics in the wave front, as well as the interaction between the wave and the upflow region.They find a weak blueshift for the Fe XII λ 195.12 and Fe XIII λ 202.04 lines in the wave front.The local velocity along the solar surface, which is deduced from the line-of-sight velocity in the wave front and the projection effect, is much lower than the typical propagation speed of the wave.A more interesting finding is that the upflow and non-thermal velocities in the upflow region are suddenly diminished after the transit of the wave front.This implies a significant change of magnetic field orientation when the wave passed.As the lines in the upflow region are redirected, the velocity along the line of sight is diminished as a result.They suggest that this scenario is more in accordance with what is proposed in the field-line stretching model of EIT waves.
pushed by the erupting flux rope.According to this model, an EIT wave should be preceded by a fastmode wave, which, however, had rarely been observed.With the unprecedented high cadence and sensitivity of the Solar Dynamics Observatory (SDO) observations, they discern a fast-moving wave front with a speed of 560 km•s −1 ahead of an EIT wave, which had a velocity of about 190 km•s −1 , in the "EIT wave" event on 27 July 2010.The results, suggesting that "EIT waves" are not fast-mode waves, confirm the prediction of their field-line stretching model for an EIT wave.In particular, it is found that the coronal Moreton wave was about 3 times faster than the EIT wave, as predicted.
to determine the relationship between coronal dimming and full halo CME.The events of full halo CME examined in their study are observed by LASCO coronagraph and taken from the CDAW CME catalogue from 1996 to 2008.Dimming events are identified by using difference images taken by EIT at the 195 Å passband.They find strong relationship between full halo CMEs and the coronal dimming events, with up to 93.3% of the front-side halo CMEs associated with the EIT 195 Å dimming events.Full halo CMEs that show no clear signatures of dimming usually have lower sky plane velocities (< 700 km•s −1 ) compared to the mean velocity of CMEs associated with dimming.Between July 5 and July 7, 2004, two intriguing fast CME-streamer interaction events are recorded by the Large Angle and Spectrometric Coronagraph.At the beginning of the events, the streamer is pushed aside from its equilibrium position upon the impact of the rapidly outgoing and expanding ejecta; then, the streamer structure, mainly the bright streamer belt, exhibits elegant large-scale sinusoidal wavelike motions.The motions are apparently driven by the restoring magnetic forces resulting from the CME impingement, suggestive of MHD kink mode propagating outward along the plasma sheet of the streamer.The mode is supported collectively by the streamer-plasma sheet structure and is therefore named "streamer wave" in the present study.With for the phase speed to decline with increasing heliocentric distance.These observations provide good examples of large-scale wave phenomena carried by coronal structures and have significance in developing seismological techniques for diagnosing plasma and magnetic parameters in the outer corona.
getic electrons (100 to 500 keV) associated with magnetic reconnection in the solar wind by the ACE and WIND spacecraft.The properties of this magnetic cloud driving reconnection and the associated energetic electron acceleration problem are discussed.Further analyses indicate that the electric field acceleration and Fermi-type mechanism are two fundamental elements in the electron acceleration processes and the trapping effect of the specific magnetic field configuration maintains the acceleration status that increases the totally gained energy.During 26−27 November 2000, a complex interplanetary coronal mass ejection composed of four flux ropes, was detected by WIND and ACE at 1 AU.
a large-scale current sheet with a spatial width of about 3000 ion inertial lengths and a shear angle of about 135 • .The two exhaust events result from fast and quasi-stationary reconnection.The related current sheets are both flat on the scale of a few hundred Earth radii and locate close to the centers of subflux ropes.The decrease of radial expansion speed of each flux rope might account for the formation of the two current sheets.Reconnections at the centers of flux ropes may change the entire topology of the flux ropes and may fragment them into smaller ones.
tures of Alfvénic fluctuations and thus classify them as Alfvén wave trains rather than flux ropes.Signatures of magnetic reconnection, generally including a plasma jet of about 30 km•s −1 within a magnetic field rotational region, are clearly present at boundaries of about 42% of the flux ropes and 14% of the wave trains.The reconnection exhausts are often observed to show a local increase in the proton temperature, density and plasma beta.About 66% of the reconnection events at flux rope boundaries are associated with a magnetic field shear angle larger than 90 • and 73% of them reveal a decrease of 20% or more in the magnetic field magnitude, suggesting a dominance of anti-parallel reconnection at flux rope boundaries.The occurrence rate of magnetic reconnection at flux rope boundaries through the years 1995−2005 is also investigated, and they find that it is relatively low around the solar maximum and much higher when approaching solar minima.The average magnetic field depression and shear angle for reconnection events at flux rope boundaries also reveal a similar trend from 1995 to 2005.Their results demonstrate for the first time that boundaries of a substan-tial fraction of small-scale flux ropes have properties similar to those of magnetic clouds, in the sense that both of them exhibit signatures of magnetic reconnection.The observed reconnection signatures could be related either to the formation of small flux ropes or to the interaction between flux ropes and the interplanetary magnetic fields.Coronal Bright Points (CBPs) are long-lived small-scale brightenings in the solar corona.They are generally explained by magnetic reconnection.However, the corresponding magnetic configurations are not well understood.Zhang, Chen et al.[47] carry out a detailed multi-wavelength analysis of two neighboring CBPs on 16 March 2007, observed in soft X-ray (SXR) and EUV channels.It is seen that the SXR light curves present quasi-periodic flashes with an interval of about 1 h superposed over the long-lived mild brightenings, suggesting that the SXR brightenings of this type of CBPs might consist of two components: one is the gentle brightenings and the other is the CBP flashes.It is found that the strong flashes of the bigger CBP are always accompanied by SXR jets.The potential field extrapolation indicates that both CBPs are covered by a dome-like separatrix surface, with a magnetic null point above.They propose that the repetitive CBP flashes, as well as the recurrent SXR jets, result from the impulsive null-point reconnection, while the long-lived brightenings are due to the interchange reconnection along the separatrix surface.Although the EUV images at high-temperature lines resemble the SXR appearance, the 171 Å and 195 Å channels reveal that the blurry CBP in SXR consists of a cusp-shaped loop and several separate bright patches, which are explained to be due to the null-point reconnection and the separatrix reconnection, respectively.
ence of a strong guide field) magnetic reconnection, and the mechanisms of electron acceleration are com-pared.In the antiparallel reconnection, the dominant acceleration occurs in the vicinity of the X line, where the magnetic field is weak.Most of these electrons come from the regions just outside of the separatrices, which move into the vicinity of the X line along the magnetic field lines.Electrons can also be nonadiabatically accelerated in the pileup region by the reconnection electric field, where the gyroradii of the electrons are comparable to the curvature radii of the magnetic field lines.Most of these electrons come from the regions inside of the separatrices, which move into the pileup region along the magnetic field lines.In the guide field reconnection, electrons are accelerated by the parallel electric field.They are firstly accelerated when moving toward the X line along the magnetic field lines, and then are further accelerated when they are funneled into the vicinity of the X line.Most of energetic electrons come from the region outside of the pair of the negative separatrices.The efficiency of such an acceleration mechanism is obviously higher than that in the antiparallel reconnection.In both the antiparallel and guide field reconnection, the mechanisms of electron acceleration favor the electrons with higher initial energy.In collisionless magnetic reconnection, the inplane Hall currents are carried mainly by the magnetized electrons.The in-plane Hall currents are directed toward the X line along the magnetic field lines just inside the separatrices and away from the X line along the separatrices.Such a current system leads to the quadrupole out-of-plane magnetic field with the peaks between the regions carrying the in-plane currents.Simultaneously, the electron flow toward the X line along the separatrices causes electron density depletions along the separatrices.The features of separatrix regions in magnetic reconnection and the relations between the electron density depletions netic reconnection.In anti-parallel reconnection, the quadrupole structures of the out-of-plane magnetic field are formed, and four symmetric electron density depletion layers can be found along the separatrices due to the effects of magnetic mirror.With the increase of the initial guide field, the symmetry of both the out-of-plane magnetic field and electron density depletion layers is distorted.When the initial guide field is sufficiently large, the electron density depletion layers along the lower left and upper right separatrices disappear.The parallel electric field in guide field reconnection is found to play an important role in forming such structures of the electron density depletion layers.The structures of the out-ofplane magnetic field B y and electron depletion layers in anti-parallel and guide field reconnection are found to be related to electron flow or in-plane currents in the separatrix regions.In anti-parallel reconnection, electrons flow towards the X line along the separatrices, and are directed away from the X line along the magnetic field lines just inside the separatrices.In guide field reconnection, electrons can only flow towards the X line along the upper left and lower right separatrices due to the existence of the parallel electric field in these regions.Two-dimensional (2-D) Particle-in-Cell (PIC)

5 -D
Adaptive Mesh Refinement (AMR) resistive Magneto Hydrodynamics (MHD) model.They reveal the successive fragmentation and merging of plasmoids in a long-thin current sheet with Lundquist number R m = 5.0 × 10 4 .It is found that several big magnetic islands are formed eventually, with many slow-mode shocks bounding around the outflow regions.The multi-scale hierarchical-like structures of the magnetic reconnection are well resolved by the model and the AMR technique of the model can capture many fine pictures (e.g., the near-singular diffusion regions) of the development and simultaneously it can save a great deal of computing resources.
planation.They simulated the SEP event by solving the five-dimensional focused transport equation numerically for 40 keV electrons with perpendicular diffusion.They find that a counter-streaming particle beam with deep depression at 90 • pitch angle can form on Parker magnetic field lines that do not directly connect to the main particle source on the Sun in the beginning of an SEP event.It can happen when a significant number of observed particles come from adjacent field lines through parallel transport to large radial distance first, hopping across field lines through perpendicular diffusion, and then getting scattered back to 1 AU, where they combine with the particles directly coming from the Sun to form a counter-streaming beam.

The
Focused Transport Equation (FTE) includes all the necessary physics for modeling the shock acceleration of energetic particles with a unified description of first-order Fermi acceleration, shock drift acceleration, and shock surfing acceleration.It can treat the acceleration and transport of particles with an anisotropic distribution.The energy spectrum of pickup ions accelerated at shocks of various previous work, in which no evident effects of CHs on CMEs in generating SEPs are found by statistically investigating 56 CME events.They extrapolate the coronal magnetic field, define CHs as the regions consisting of only open magnetic field lines and perform a similar analysis on this issue for 76 events in total by extending the study interval to the end of 2008.Three key parameters, CH proximity, CH area and CH relative position, are involved in the analysis.The new result confirms the previous conclusion that CHs do not show any evident effect on CMEs in causing SEP events.It is generally believed that gradual SEPs are accelerated by shocks associated with CMEs.Using an ice-cream cone model, the radial speed and angular width of 95 CMEs associated with SEP events during 1998−2002 are calculated by Pan et al.
perform twodimensional (2-D) Particle-in-Cell (PIC) simulations to study the evolution of electron holes at different plasma conditions; they find that the evolution is determined by combined actions between the transverse instability and the stabilization by the background magnetic field.In very weakly magnetized plasma (Ω e ω pe , where Ω e and ω pe are the electron gyrofrequency and plasma frequency, respectively), the transverse instability dominates the evolution of the electron holes.The parallel cut of the perpendicular electric field (E ⊥ ) has bipolar structures, accompanied by the kinking of the electron holes.Such structures last for only tens of electron plasma periods.With the increase of the background magnetic field, the evolution of the electron holes becomes slower.The bipolar structures of the parallel cut of E ⊥ in the electron holes can evolve into unipolar structures.In very strongly magnetized plasma (Ω e ω pe ), the unipolar structures of the parallel cut of E ⊥ can last for thousands of electron plasma periods.At the same time, the perpendicular electric field (E ⊥ ) in the electron holes can also influence electron trajectories passing through the electron holes, which results in variations of charge density along the direction per-pendicular to the background magnetic field outside the electron holes.When the amplitude of the electron hole is sufficiently strong, streaked structures of E ⊥ can be formed outside the electron holes, which then emit electrostatic whistler waves because of the interactions between the streaked structures of E ⊥ and vibrations of the kinked electron holes.
perform two-dimensional electromagnetic Particle-in-Cell (PIC) simulations in the (x, y) plane to study magnetic structures associated with electron holes under different plasma conditions.In the simulations, the background magnetic field (B 0 = B 0 e x ) is along the x direction.The combined actions between the transverse instability and stabilization by the background magnetic field lead to the generation of the electric field E y .Then electrons suffer the electric field drift and produce the current in the z direction, which leads to the fluctuating magnetic field along the x and y directions.Meanwhile, the motion of the electron holes along the x direction and the existence of the electric field E y generate the fluctuating magnetic field along the z direction.In very weakly magnetized plasma (Ω e ω pe , where Ω e and ω pe are the electron gyrofrequency and electron plasma frequency, respectively), the transverse insta-bility is very strong and the magnetic structures associated with electron holes disappear quickly.When Ω e is comparable to ω pe , the parallel cut of the fluctuating magnetic field δ Bx and δ Bz has unipolar structures in the electron holes, while the parallel cut of fluctuating magnetic field δ By has bipolar structures.In strongly magnetized plasma (Ω e > ω pe ), electrostatic whistler waves with streaked structures of E y are excited.The fluctuating magnetic field δ Bx and δ Bz also have streaked structures.The relevance between their simulation results and the magnetic structures associated with electron holes observed in the plasma sheet is also discussed.Previous particle-in-cell simulations have evidenced that supercritical, quasi-perpendicular shocks are non-stationary.By separating the incident ions into Reflected (R) and Directly Transmitted (DT) in a non-stationary perpendicular shock.The upstream ion distributions have two parts corresponding to the R and incident ions respectively, while the R ions have higher energy.The downstream ions have a core-ring distribution.The core and ring parts correspond to the DT and R ions, respectively.The ion distributions depend largely on the non-stationary shock structure.The percentage of the reflected ions cyclically varies in time with a period equal to the shock self-reformation cycle, and the number of the R ions increases with the steepness of the shock ramp.Electron phase space holes (electron holes) are found to be unstable to the transverse instability.Two-dimensional (2-D) electromagnetic Particle-in-Cell simulations are performed by Du et al. [65] to investigate the structures of the fluctuating magnetic field associated with electron holes.The combined actions between the transverse instability and the stabilization by the background magnetic field (B 0 = B 0 e x ) lead a one-dimensional electron hole into several 2-D electron holes which are isolated in both the x and y directions.The electrons trapped in these 2-D electron holes suffer the electric field drift v E = E × B 0 /B 2 0 due to the existence of the perpendicular electric field E y , which generates the current along the z direction.Then, the unipolar and bipolar structures are formed for the parallel cut of the fluctuating magnetic field along the x and y directions, respectively.At the same time, these 2-D electron holes move along the x direction, and the unipolar structures are formed for the parallel cut of the fluctuating magnetic field along the z direction.
address the stochastic heating of minor ions by obliquely-propagating low-frequency Alfvén waves in the solar wind.An important characteristics of the stochastic heating is unearthed by means of test particle simulation.That is, when the wave amplitude exceeds some threshold condition for stochasticity, the time-asymptotic kinetic temperature associated with the minor ions becomes independent of the wave amplitude, and it always approaches the value dictated by the Alfvén speed, to wit, T kin ≈ m i v 2 A /2.During the course of the heat-ing process the minor ions gain a net average parallel speed, v ≈ v A in the laboratory frame.These results are consistent with observations which find that minor heavy ions often move faster than the local protons with a speed roughly equal to the local Alfvén speed.
utilize a power law function to model the omnidirectional differential fluxes of superthermal electrons observed by Cluster in the magnetosheath.By assuming an isotropic pitch angle distribution and performing a nonlinear least squares fitting, they can calculate the index a of the power law distribution of the superthermal electrons.They find that in the magnetosheath the indices a of the power law distributions decrease with the increase of ω pe /Ω e .It is consistent with the results of the recent particle-in-cell simulations, which described the electron distributions scattered by enhanced whistler waves.This is the first reported observation of this relation in space plasma.
component overset grid to solar wind simulation with a three-dimensional (3-D) Solar-InterPlanetary Conservation Element/Solution Element MHD (SIP-CESE MHD) model.The essential focus of their numerical model is devoted to dealing with (1) the singularity and mesh convergence near the poles via the use of the six-component grid system, (2) the ∇ • B constraint error via an easy-to-use cleaning procedure by a fast multigrid Poisson solver, (3) the Courant-Friedrichs-Levy number disparity via the Courantnumber insensitive method, (4) the time integration by multiple time stepping, and (5) the timedependent boundary condition at the subsonic region by limiting the mass flux escaping through the solar surface.In order to produce fast and slow plasma streams of the solar wind, they include the volumetric heating source terms and momentum addition by involving the topological effect of the magnetic field expansion factor f s and the minimum angular distance θ b (at the photosphere) between an open field foot point and its nearest coronal hole boundary.These considerations can help them easily code the existing program, conveniently carry out the parallel implementation, efficiently shorten the computation time, greatly enhance the accuracy of the numerical solution, and reasonably produce the structured solar wind.The numerical study for the 3-D steady-state background solar wind during Carrington rotation 1911 from the Sun to Earth is chosen to show the above-mentioned merits.Their numerical results have demonstrated overall good agreements in the solar corona with the Large Angle and Spectrometric Coronagraph on board the SOHO satellite and at 1 AU with WIND observations.
tems and solvers.The computational domain from the Sun to Earth space is decomposed into the near-Sun and off-Sun domains, which are respectively constructed with a Yin-Yang overset grid system and a Cartesian Adaptive Mesh Refinement (AMR) grid system and coupled with a domain connection interface in the overlapping region between the near-Sun and off-Sun domains.The space-time conservation element and solution element method is used in the near-Sun domain, while the Harten-Lax-Leer method is employed in the off-Sun domain.The Yin-Yang overset grid can avoid well-known singularity and polar grid convergence problems and its body-fitting property helps achieve high-quality resolution near the solar surface.The block structured AMR Cartesian grid can automatically capture far-field plasma flow features, such as heliospheric current sheets and shock waves, and at the same time, it can save signif-icant computational resources compared to the uniformly structured Cartesian grid.A numerical study of the solar wind structure for Carrington rotation 2069 shows that the newly developed hybrid MHD solar wind model successfully produces many realistic features of the background solar wind, in both the solar corona and interplanetary space, by comparisons with multiple solar and interplanetary observations.

Earth connection event on 4
November, 1997 by using a 3-D SIP-CESE MHD simulation, in which a spherical high-speed, high-pressure and high-density plasmoid at S14 • , W34 • is used to mimic CME disturbance.The result provide a relatively satisfactory comparison with the WIND spacecraft observations, such as southward interplanetary magnetic field and large-scale smooth rotation of the magnetic field associated with the CME.
space-time Conservation Element and Solution Element (CESE) method for simulations of Magnetohydrodynamic (MHD) problems in general curvilinear coordinates by using an Adaptive Mesh Refinement (AMR) grid system.By transforming the governing MHD equations from the physical space (x, y, z) to the computational space (ξ, η, ζ) while retaining the form of conservation, the CESE method is established for MHD in the curvilinear coordinates.Utilizing the parallel AMR package PARAMESH, they present the first implementation of applying the AMR CESE method for MHD (AMR-CESE-MHD) in both Cartesian and curvilinear coordinates.To show the validity and capabilities of the AMR-CESE-MHD code, a suite of numerical tests in two and three dimensions including ideal MHD and resistive MHD are carried out, with two of them in both Cartesian and curvilinear coordinates.Numerical tests show that their results are highly consistent with those obtained previously by other authors, and the results under both coordinate systems confirm each other very well.

a
photospheric vector magnetogram according to a new version of the CESE scheme with the full MHD equations.The bottom boundary condition is prescribed in a similar way as in the stress-and-relax method by changing the transverse field incrementally to match the magnetogram, and other boundaries of the computational box are set by the nonreflecting boundary conditions.Applications to the well-known benchmarks for nonlinear force-free-field reconstruction, the Low & Lou force-free equilibria, rotation 2070 in 2008 to investigate the properties of the background solar wind by using the 3-D SIP-CESE MHD model.They also study the effects of polar magnetic fields on the characteristics of the solar corona and the solar wind by conducting simulations with an axisymmetric polar flux added to the observed magnetic field.The numerical results are compared with the observations from multiple satellites, such as the SOHO, Ulysses, STEREO, WIND and ACE.The comparison demonstrates that the first simulation with the observed magnetic fields reproduces some observed peculiarities near the Sun, such as relatively small polar coronal holes, the presence of mid-and lowlatitude holes, a tilted and warped current sheet, and the broad multiple streamers.The numerical results also capture the inconsistency between the locus of the minimum wind speed and the location of the heliospheric current sheet, and predict slightly slower and cooler polar streams with a relatively smaller latitudinal width, broad low-latitude intermediate-speed streams, and globally weak magnetic field and low density in the heliosphere.The second simulation with strengthened polar fields indicates that the weak polar fields in the current minimum play a crucial role in determining the states of the corona and the solar wind.

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D SIP-CESE MHD model and magnetogram data from a Carrington Rotation (CR) 1897 to compare the three commonly used heating methods, i.e.the Wentzel-Kramers-Brillouin (WKB) Alfvén wave heating method, the turbulence heating method and the volumetric heating method.Their results show that all three heating models can basically reproduce the bimodal structure of the solar wind observed near the solar minimum.The results also demonstrate that the major acceleration interval terminates about 4 R s for the turbulence heating method and 10 R s for both the WKB Alfvén wave heating method and the volumetric heating method.The turbulence heating and the volumetric heating methods can capture the observed changing trends by the WIND satellite, while the WKB Alfvén wave heating method does not.

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The combination of the projected normal characteristic method and the mass flux limit enables the model to reproduce reasonable distributions of the plasma density, temperature and velocity on the solar surface and incorporation of the time-dependent magnetograms into the model is under development.(3) The model provides a unified treatment of flow evolution in space and time and keeps the local and global space-time flux conservation in a coherent and efficient manner.

( 5 )( 6 )
schemes in Cartesian coordinate such as Total Variation Diminishing (TVD) scheme and Finite Volume Method (FVM) can be applied directly to the transformed system.This feature provides us many flexible alternatives of solving the transformed governing equations in (ξ, η, ζ) and then we recover the solution in the physical space through the transformation to obtain the solar wind solution.
a self-consistent global structure on the source surface of 2.5 R s covering four different phases of solar activity.This model takes into the consideration of the topological effect of f s and θ b .The model uses as input for 136 Carrington Rotations (CRs) covering four different phases of solar activity: (1) an empirical model of the magnetic field topology on the source surface using Line-of-Sight (LOS) photospheric field (B los ) measurements by Wilcox Solar Observatory (WSO); and (2) an empirically derived global coronal density distribution using K coronal polarized Brightness (pB) by MKIII in High Altitude Observator (HAO).The solar wind speed on the source surface is specified by the function of both f s and θ b .Then the coronal mass outputs are analyzed and the self-consistent global distribution on the source surface is numerically studied for the four different phases.Finally, the model estimates the solar wind speed at 1 AU as a simple function of the speed on the source surface.The results indicate reasonable semiquantitative agreement with observations at different phases of solar activity.
tive disturbances are induced by the same-side events (referring to the CMEs whose source located on the same side of the Heliospheric Current Sheet (HCS) as the Earth), while only a small portion is associated with the opposite-side events (the CMEs source lo-cated on the opposite side of the HCS as the Earth); the ratio is 128 vs. 46, and it reaches 41 vs. 14 for the intense ionospheric negative storms.In addition, the ionospheric negative storms associated with the sameside events are often more intense.A comparison of the same-side event(4 April 2000) and the oppositeside event(2 April 2001) shows that the intensity of the ionospheric negative storm caused by the sameside event is higher than that by the opposite-side event, although their initial conditions are quite similar.Their preliminary results show that the HCS has an "impeding" effect to CMEIPS, which results in a shortage of energy injection in the auroral zone and restraining the development of ionospheric negative perturbations.8 Proposed MissionsCMEs represent a great concentration of mass and energy input into the lower corona.They have come to be recognized as the major driver of physical conditions change in the Sun-Earth system.Consequently, observations of CMEs are important for understanding and ultimately predicting space weather conditions.Wu et al.[81] discuss a proposed mission, the Solar Polar Orbit Radio Telescope (SPORT) mission, which will observe the propagation of interplanetary CMEs to distances of near 0.35 AU from the Sun.The orbit of SPORT is an elliptical solar polar orbit.The inclination angle between the orbit and ecliptic plane should be about 90 • .The main payload on board SPORT will be an imaging radiometer working at the meter wavelength band (radio telescope), which can follow the propagation of interplanetary CMEs.The images that are obtained by the radio telescope embody the brightness temperature of the objectives.Due to the very large size required for the antenna aperture of the radio telescope, they adopt interferometric imaging technology to reduce it.Interferometric imaging technology is based on indirect spatial frequency domain measurements plus Fourier transformation.