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| 1 | A 3rd Order WENO GLM-MHD Scheme for Magnetic Reconnection显示文摘A new numerical scheme of 3rd order Weighted Essentially Non-Oscillatory (WENO) type for 2.5D mixed GLM-MHD in Cartesian coordinates is proposed. The MHD equations are modified by combining the arguments as by Dellar and Dedner et al to couple the divergence constraint with the evolution equations using a Generalized Lagrange Multiplier (GLM). Moreover, the magnetohydrodynamic part of the GLM-MHD system is still in conservation form. Meanwhile, this method is very easy to add to an existing code since the underlying MHD solver does not have to be modified. To show the validation and capacity of its application to MHD problem modelling, interaction between a magnetosonic shock and a denser cloud and magnetic reconnection problems are used to verify this new MHD code. The numerical tests for 2D Orszag and Tang's MHD vortex, interaction between a magnetosonic shock and a denser cloud and magnetic reconnection problems show that the third order WENO MHD solvers are robust and yield reliable results by the new mixed GLM or the mixed EGLM correction here even if it can not be shown that how the divergence errors are transported as well as damped as done for one dimensional ideal MHD by Dedner et al. | FENG Xueshang ZHOU Yufen HU Yanqi | 2006 | 空间科学学报2006，26，1： | 9 |
| 2 | GPU-accelerated computing of three-dimensional solar wind background显示文摘High-performance computational models are required to make the real-time or faster than real-time numerical prediction of adverse space weather events and their influence on the geospace environment.The main objective in this article is to explore the application of programmable graphic processing units(GPUs)to the numerical space weather modeling for the study of solar wind background that is a crucial part in the numerical space weather modeling.GPU programming is realized for our Solar-Interplanetary-CESE MHD model(SIP-CESE MHD model)by numerically studying the solar corona/interplanetary solar wind.The global solar wind structures are obtained by the established GPU model with the magnetic field synoptic data as input.Meanwhile,the time-dependent solar surface boundary conditions derived from the method of characteristics and the mass flux limit are incorporated to couple the observation and the three-dimensional(3D)MHD model.The simulated evolution of the global structures for two Carrington rotations 2058 and 2062 is compared with solar observations and solar wind measurements from spacecraft near the Earth.The MHD model is also validated by comparison with the standard potential field source surface(PFSS)model.Comparisons show that the MHD results are in good overall agreement with coronal and interplanetary structures,including the size and distribution of coronal holes,the position and shape of the streamer belts,and the transition of the solar wind speeds and magnetic field polarities. | FENG XueShang ZHONG DingKun XIANG ChangQing ZHANG Yao | 2013 | Science China Earth Sciences2013，56，11： | 7 |
| 3 | A comparative study on 3-D solar wind structure observed by Ulysses and MHD simulation显示文摘During Ulysses’ first rapid pole-to-pole transit from September 1994 to June 1995, its observations showed that middle- or high-speed solar winds covered all latitudes except those between ?20° and +20° near the ecliptic plane, where the velocity was 300―450 km/s. At poleward 40°, however, only fast solar winds at the speed of 700―870 km/s were observed. In addition, the transitions from low-speed wind to high-speed wind or vice versa were abrupt. In this paper, the large-scale structure of solar wind observed by Ulysses near solar minimum is simulated by using the three-dimensional numerical MHD model. The model com- bines TVD Lax-Friedrich scheme and MacCormack II scheme and decomposes the calculation region into two re- gions: one from 1 to 22 Rs and the other from 18 Rs to 1 AU. Based on the observations of the solar photospheric magnetic field and an addition of the volumetric heating to MHD equations, the large-scale solar wind structure mentioned above is reproduced by using the three-dimensional MHD model and the numerical results are roughly consistent with Ulysses’ observations. Our simulation shows that the initial magnetic field topology and the addition of volume heating may govern the bimodal structure of solar wind observed by Ulysses and also demonstrates that the three-dimensional MHD numerical model used here is efficient in modeling the large-scale solar wind structure. | FENG Xueshang, XIANG Changqing, ZHONG Dingkun & FAN Quanlin SIGMA Weather Group, Key Laboratory of Space Weather Key Labo- ratory of Geospace Environment and Geodesy, Ministry of Education, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100080, China | 2005 | Chinese Science Bulletin2005，50，7： | 6 |
| 4 | An asynchronous and parallel time-marching method: Application to three-dimensional MHD simulation of solar wind显示文摘An asynchronous and parallel time-marching method for three-dimensional (3D) time-dependent magnetohydrodynamic (MHD) simulation is used for large-scale solar wind simulation. It uses different local time steps in the corona and the heliosphere according to the local Courant-Friedrichs-Levy (CFL) conditions. The solar wind background with observed solar photospheric magnetic field as input is first presented. The simulation time for the background solar wind by using the asynchronous method is <1/6 of that by using the normal synchronous time-marching method with the same computation precision. Then, we choose the coronal mass ejection (CME) event of 13 November, 2003 as a test case. The time-dependent variations of the pressure and the velocity configured from a CME model at the inner boundary are applied to generate transient structures in order to study the dynamical interaction of a CME with the background solar wind flow between 1 and 230 Rs. This time-marching method is very effective in terms of computation time for large-scale 3D time-dependent numerical MHD problem. In this validation study, we find that this 3D MHD model, with the asynchronous and parallel time-marching method, provides a relatively satisfactory comparison with the ACE spacecraft obser- vations at L1 point. | SHEN Fang FENG XueShang SONG WenBin | 2009 | Science China(Technological Sciences)2009，52，10： | 6 |
| 5 | Magnetic reconnection structures in the boundary layer of an interplanetary magnetic cloud显示文摘An interplanetary magnetic diffusion region was detected by WIND during 0735-0850 UT on May 15, 1997 when the front boundary layer of a magnetic cloud passed through the spacecraft about 190 earth radii upstream of the earth. The main signals of magnetic reconnection processes are: (ⅰ) Flow reversal was detected at about 0810 UT. The counter-streaming flows have the speeds of about 65 and 41 km/s, respectively, with an angle of about 140 degree between them. (ⅱ) Hall magnetic field was detected. The Hall fields ?By and +By, perpendicular to the X-Z plane, with their magnitude up to ~7.0 nT, are superposed upon a guide field about 12 nT. (ⅲ) Alfvenic fluctuations are obviously intensified inside the reconnection region; at the front boundary of the reconnection region, a slow-mode-like discontinuity was detected. (ⅳ) Ions are heated intensively inside the reconnection region, with their temperature three times higher than that ahead of the boundary layer; electrons are also heated, with a little enhancement in their temperature. The above observations indicate that magnetic reconnection processes could take place in interplanetary space. | WEI Fengsi LIU Rui FENG Xueshang ZHONG Dingkun YANG Fang | 2004 | Science China(Technological Sciences)2004，47，1： | 4 |
| 6 | Numerical study of successive CMEs during November 4―5, 1998显示文摘We present the solar-terrestrial transit process of three successive coronal mass ejections (CMEs) of November 4―5, 1998 originating from active region 8375 by using a time-dependent three-dimensional magnetohydrodynamics (MHD) simula-tion. These CMEs interacted with each other while they were propagating in inter-planetary space and finally formed a 'complex ejecta'. A newly developed SIP-CESE MHD model was applied to solve MHD equations numerically. The quiet solar wind was started from Parker-like 1D solar wind solution and the magnetic field map was calculated from the solar photospheric magnetic field data. In our simulation, the ejections were initiated using pulse in the real active region 8375. The interplanetary disturbance parameters, such as speed, direction and angular size of the expanding CME, were determined from the SOHO/LASCO data with the cone-model. We discussed the three-dimensional aspects of the propagation, in-teraction and merging of the three ejections. The simulated interplanetary shocks were compared with the nearby-Earth measurement. The results showed that our simulation could reproduce and explain some of the general features observed by satellite for the 'complex ejecta'. | ZHOU YuFen & FENG XueShang SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190, China | 2008 | Science China(Technological Sciences)2008，51，10： | 3 |
| 7 | Predicting the shock arrival time using 1D-HD solar wind model显示文摘A 1D-HD shock propagation model is established 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 our 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 our 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 our 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 mod- els. These results might demonstrate a potential capability of our model in terms of real-time forecasting. | ZHANG Ying CHEN JingYi FENG XueShang | 2010 | Chinese Science Bulletin2010，55，11： | 3 |
| 8 | Numerical study of magnetic reconnection process near interplanetary current sheet显示文摘The third order accurate upwind compact difference scheme has been applied to the numerical study of the magnetic reconnection process possibly occurring near the interplanetary current sheet, under the framework of the two-dimensional compressible magnetohydrodynamics (MHD). Our results here show that the driven reconnection near the current sheet can occur within 10-30 min for the interplanetary high magnetic Reynolds number, RM =2 000-10 000, the stable magnetic reconnection structure can be formed in hour-order of magnitude, and there are some basic properties such as the multiple X-line reconnections, vortical velocity structures, filament current systems, splitting and collapse of the high-density plasma bulk. These results are helpful in understanding and identifying the magnetic reconnection phenomena near the interplanetary current sheets. | Fengsi Wei Qiang Hu Xueshang Feng | 2001 | Chinese Science Bulletin2001，46，2： | 3 |
| 9 | Three Dimensional Simulation of the Steady Solar Wind in Carrington Rotation 1935显示文摘A three-dimensional MHD simulation is conducted to study the steady solar wind in Carrington Rotation (CR) 1935 by using the three-dimensional numerical magnetohydrodynamic (MHD) model introduced by Feng et al The numerical results demonstrate that the neutral current sheet has two peaks and two valleys, which is consistent with the result of PFSS model at Wilcox Solar Observatory (WSO). The obtained proton number density at 2.5 Rs is of the same order of magnitude as the result estimated from K-coronal brightness during the CRs 1733-1742 in 1983 made by Wei et al. The radial velocity profile along heliocentric distance is consistent with that of low solar wind speed deduced by Sheeley and Wang et al. However, it is not able to reproduce the fast-speed flow in coronal holes and slow solar wind in streamers because of oversimplified energy equation adopted in our model. Future efforts must be made to remedy this deficiency. | XIANG Changqing FENG Xueshang YAO Jiusheng | 2006 | 空间科学学报2006，26，1： | 2 |
| 10 | Responses of the magnetotail plasma sheet to two interplanetary shocks:TC-1 observations显示文摘Two interplanetary shocks are examined to determine the responses of the magnetic field and plasma in the plasma sheet upon the shock impacts by using TC-1 observational data.The two shocks are observed by WIND on November 7,2004.Prior to and after the shock,the IMF is either weakly southward or northward.The responses of the plasma sheet to the two shocks are intense and much similar.When the shock interacts with the magnetosphere,the magnetic field impulsively increases 1-2 min after the geomagnetic field sudden impulse (SI) judged from the Sym-H index change,and the magnetic field line is stretched.On the other hand,all of the ion density,the ion temperature,and the velocity of ion flow in the plasma sheet increase.Interestingly,quasi-periodical oscillations of the ion flow are suddenly enhanced,and the plasma flow is basically perpendicular to the local magnetic field.The responses of the magnetic field and the plasma are nearly simultaneous.The responses in the plasma sheet are probably caused by the lateral compression due to the dynamic pressure enhancement downstream the shock when the shock propagates antisunward in the magnetosheath. | YAO Li ZUO PingBing FENG XueShang LIU ZhenXing | 2010 | Chinese Science Bulletin2010，55，6： | 2 |
| 11 | WIND observations of plasma waves inside the magnetic cloud boundary layers显示文摘Based on the WIND observational data for the plasma waves from thermal noise receptor (TNR) working on the frequency 4―256 kHz and the solar wind and the magnetic fields, we analyze the plasma wave activities in the 60 magnetic cloud’s boundary layers (BLs) and find that there are often various plasma wave activities in the BLs, which are different from those in the adjacent solar wind (SW) and the magnetic clouds (MC). The basic characteris-tics are that: (1) the enhancement of the Langmuir wave near the electronic plasma frequency (fpe) is a dominant wave ac-tivity, which occupies 75% investigated samples; (2) the events enhanced both in the langmuir and ion acustic (f < fpe) waves are about 60% of investigated samples; (3) broadband, continuous enhancement events in the plasma wave activities were observed in the whole frequency band of TNR, and about 30% of the 60 samples, however, were not observed in the SW and the MC investigated events; (4) although the ratio of the temperatures between the electon and proton, Te/Tp≤1, the ion caustic wave enhancement activities are still often observed in the BLs, which makes it difficult to ex- plain them by the traditional plasma theory. New results reported in this paper further show that the magnetic cloud’s BL is an important dynamic structure, which could provide useful diagnosis for understanding the cloud’s BL physics and could expand a space developing space plasma wave theory. | WEI Fengsi ZHONG Dingkun FENG Xueshang YANG Fang LIU Rui | 2005 | Chinese Science Bulletin2005，50，18： | 2 |
| 12 | An improved CESE method and its application to steady-state coronal structure simulation显示文摘This paper presents an improved space-time conservation element and solution element(CESE)method by applying a non-staggered space-time mesh system and simply improving the calculation of flow variables and applies it to magnetohydrodynamics(MHD)equations.The improved CESE method can improve the solution quality even with a large disparity in the Courant number(CFL)when using a fixed global marching time.Moreover,for a small CFL(say<0.1),the method can significantly reduce the numerical dissipation and retain the solution quality,which are verified by two benchmark problems.And meanwhile,comparison with the original CESE scheme shows better resolution of the improved scheme results.Finally,we demonstrate its validation through the application of this method in three-dimensional coronal dynamical structure with dipole magnetic fields and measured solar surface magnetic fields as the initial input. | ZHOU YuFen FENG XueShang | 2014 | Science China Earth Sciences2014，57，1： | 2 |
| 13 | Observations of the field-aligned residual flow inside magnetic cloud structure显示文摘In this paper,we report two MC events observed by WIND spacecraft with good examples of fieldaligned residual flow inside the MC structure. For both events,the co-moving frames are determined through the deHoffman-Teller (HT) analysis and the axial orientations are inferred by the newly developed minimal residue (MR) method. The nature coordinate system for both events are constructed with velocity of the HT frame and the inferred MC axis,the field and flow remaining in the HT frame are analyzed at this coordinate system. As a result,we find that the residual flows in the co-moving HT frame of the two MC events are almost anti-parallel to the helical magnetic field. We speculate that the field-aligned residual flows are large scale coherent hydrodynamic vortices co-moving with the MCs at the supersonic speed near 1 AU. Data analyses show that the event in slow ambient solar wind is expanding at 1 AU and another one in fast solar wind does not show apparent expansion. Proton behaviors for both events are quasi-isothermal. Accelerated HT analysis shows that both events have no suitable HT frame with constant accelerations,which suggests that both events may be moving at the constant speed near 1 AU under the assumptions of the HT analysis. For both events,the ratio of the dynamic pressure to the magnetic pressure is larger than that of the thermal pressure to magnetic pressure,which suggests that the dynamic effects due to the plasma flows remaining in the co-moving HT frame are more important than the thermal effects in the study of MC evolution and propagation. | LI HuiJun FENG XueShang ZUO PingBing XIE YanQiong | 2009 | Science China(Technological Sciences)2009，52，9： | 2 |
| 14 | A unified and very fast way for computing the global potential and linear force-free fields显示文摘 | Jiang Chaowei Feng Xueshang | 2012 | Solar Physics2012，281，2： | 1 |
| 15 | Splitting Based Scheme for Three-dimensional MHD with Dual Time Stepping显示文摘A new hybrid numerical scheme of combining an E-CUSP(Energy-Convective Upwind and Split Pressure) method for the fluid part and the Constrained Transport(CT) for the magnetic induction part is proposed.In order to avoid the occurrence of negative pressure in the reconstructed profiles and its updated value,a positivity preserving method is provided.Furthermore,the MHD equations are solved at each physical time step by advancing in pseudo time.The use of dual time stepping is beneficial in the computation since the use of dual time stepping allows the physical time step not to be limited by the corresponding values in the smallest cell and to be selected based on the numerical accuracy criterion.This newly established hybrid scheme combined with positivity preserving method and dual time technique has demonstrated the accurateness and robustness through numerical experiments of benchmark problems such as the 2D Orszag-Tang vortex problem and the3 D shock-cloud interaction problem. | FU Huazheng FENG Xueshang | 2015 | 空间科学学报2015，35，1： | 1 |
| 16 | A CLASS OF TWO-STEP TVD MACCORMACK TYPE NUMERICAL SCHEME FOR MHD EQUATIONS显示文摘In this paper, a new numerical scheme of Total Variation Diminishing (TVD) MacCormack type for MagnetoHydroDynamic (MHD) equations is proposed by taking into account of the characteristics such as convergence, stability, resolution. This new scheme is established by solving the MHD equations with a TVD modified MacCormack scheme for the purpose of developing a scheme of quick convergence as well as of TVD property. To show the validation, simplicity and practicability of the scheme for modelling MHD problems, a self-similar Cauchy problem with the discontinuous initial data consisting of constant states, and the collision of two fast MHD shocks, and two-dimensional Orszag and Tang's MHD vortex problem are discussed with the numerical results conforming to the existing results obtained by the Roe type TVD, the high-order Godunov scheme,and Weighted Essentially Non-Oscillatory (WENO) scheme. The numerical tests show that this two-step TVD MacCormack numerical scheme for MHD system is of robust operation in the presence of very strong waves, thin shock fronts, thin contact and slip surface discontinuities. | FENG Xueshang WEI Fengsi ZHONG Dingkun(Center for Space Science and Applied Research, The Chinese Academy of Sciences, Beijing 100080) | 2003 | 空间科学学报2003，23，6： | 1 |
| 17 | Validation of the 3D AMR SIP–CESE Solar Wind Model for Four Carrington Rotations显示文摘 | Xueshang Feng Liping Yang Changqing Xiang Caowei Jiang Xiaopeng Ma S. Wu DingKun Zhong Yufen Zhou | 2012 | Solar Physics2012，，1： | 1 |
| 18 | SIP-CESE MHD model of solar wind with adaptive mesh refinement of hexahedral meshes显示文摘 | Xueshang Feng Changqing Xiang Dingkun Zhong Yufen Zhou Liping Yang Xiaopeng Ma | 2014 | Computer Physics Communications2014，，7： | 1 |
| 19 | Electron Acceleration in a Dynamically Evolved Current Sheet Under Solar Coronal Conditions显示文摘 | Shaohua Zhang A. M. Du Xueshang Feng Xin Cao Quanming Lu Liping Yang Gengxiong Chen Ying Zhang | 2014 | Solar Physics2014，，5： | 1 |
| 20 | A New Prediction Method for the Arrival Time of Interplanetary Shocks显示文摘 | Xueshang Feng Xinhua Zhao | 2006 | Solar Physics2006，，1： | 1 |
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