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The low-latitude sodium layer:comparative data from lidar observations at Hainan,China and São Paulo,Brazil

Earth and Planetary Physics 2025年第1期9卷 39-53页

作者： Fang Wu Jing Jiao GuoTao Yang LiFang Du ZhengKuan Liu HaoRan Zheng JiXin Guo ShaoHua Gong YaJun Zhu State Key laboratory of space weather National Space Science CenterChinese Academy of SciencesBeijing 100190China Hainan National Field Science Observation and Research Observatory for space weather National Space Science CenterChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China China-Brazil Joint laboratory for space weather NSSC/INPESão Josédos Campos 12227-010Brazil School of Physics and Electronics Engineering Hainan Normal UniversityHaikou 571158China

Physical and chemical processes observed in the mesosphere and thermosphere above the Earth’s low latitudes are complex and highly interrelated to activity in the low-latitude *** sodium detected by lidar can yield clues to dynamic and chemical processes in these spatial layers above the Earth’s *** paper is based on sodium layer data collected at two low-latitude stations,one in the northern hemisphere and one in the *** low-latitude sodium layer exhibits conspicuous seasonal variations in shape,density,and altitude;these variations are similar between Earth’s hemispheres:sodium layer density at both stations reaches its seasonal maximum in autumn and minimum in ***,maximal Na density over Brazil is greater than that over *** variations of Na density above the two low-latitude stations are also similar;at both,maxima are observed before *** variations of the Na layer over Brazil that differ from those observed in the northern hemisphere may be related to the South Atlantic Magnetic Anomaly(SAMA)or fountain *** suggest that low-latitude Na layer data may provide useful additional evidence that could significantly improve the low-latitude part of the WACCM-Na model.

关键词： metallic sodium layer seasonal variation nocturnal variation lidar

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High-precision magnetic field measurement system based on a coherent population trapping magnetometer onboard the SATech-01 satellite

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Science China Technological Sciences 2025年

作者： Hongbo XUE Wei SONG Haoran ZHAO Yiteng ZHANG Shanzhi YE Jindong WANG Ran TAO Peng SANG Keli CHEN Xingzi BI Bingjun CHENG Bin ZHOU Yongliang XUE Yingying TANG Liu LIU Jinsong LI Xiaocheng ZHU Baoquan LI Jinguo LIU Wen CHEN Xiaofeng ZHANG Yonghe ZHANG Lei LI State Key laboratory of space weather National Space Science Center Chinese Academy of Sciences Key laboratory of Solar Activity and space weather National Space Science Center Chinese Academy of Sciences Key laboratory of Electronics and Information Technology for space Systems National Space Science Center Chinese Academy of Sciences State Key laboratory of Robotics Shenyang Institute of Automation Chinese Academy of Sciences Innovation Academy for Microsatellites Chinese Academy of Sciences

On July 27, 2022, a high-precision system for measuring the magnetic field based on a coherent population trapping magnetometer（referred to as the CPT system） was launched onboard the space Advanced Technology demonstration satellite（SATech-01） by a ZK-1A rocket. The payload comprises a scalar coherent population trapping magnetometer（CPTM）, triaxial anisotropic magnetoresistance magnetometer（AMRM）, and nano star tracker mounted on a non-magnetic telescopic tubular mast. This configuration enables synchronized measurement of scalar and vector geomagnetic fields, as well as the attitude,making the payload with its compact sensors suitable for applications on miniature satellite platforms. On November 7, 2022,the novel telescopic tubular mast was deployed in orbit, extending to a length of 5.28 m. The CPTM, an absolute scalar magnetometer with an omnidirectional sensor, is the first China-developed quantum/atomic magnetometer successfully operating in space. In orbit, the CPTM has sensitivity of ～10 pT/Hz1/2and can automatically operate under complex magnetic field variations. The difference between the scalar fields obtained using the CPTM and CHAOS model has a mean deviation of–3.73 n T and a standard deviation of 26.11 nT（1σ）, without on-orbit calibration or correction. The miniaturized AMRM has a sensitivity of ～0.3 n T/Hz1/2and maintains stable and reliable operation in orbit. The low-power and miniaturized nano star tracker has a measurement uncertainty of 14.23″（1σ） in orbit. The mission has realized the on-orbit technical verification of the integrated and synchronized detection of the vector magnetic field and attitude and fully validated the system's performance,automation level, and reliability.

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Accurate quantification of the algebraic,multiplicative algebraic,and simultaneous iterative reconstruction techniques in ionosphere rebuilding based on the TIEGCM assessment

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Earth and Planetary Physics 2025年第1期9卷 117-126页

作者： Ao Qi HaiBing Ruan Institute of space weather Nanjing University of Information Science and TechnologyNanjing 210044China Key laboratory of Geospace Environment University of Science&Technology of ChinaChinese Academy of SciencesHefei 230026China

The algebraic reconstruction technique(ART),multiplicative algebraic reconstruction technique(MART),and simultaneous iterative reconstruction technique(SIRT)are computational methodologies extensively utilized within the field of computerized ionospheric tomography(CIT)to facilitate three-dimensional reconstruction of the ionospheric ***,reconstruction accuracy elicits recurrent disputes over its practical application,and people usually attribute this issue to incomplete and uneven coverage of the *** Thermosphere Ionosphere Electrodynamics General Circulation Model(TIEGCM)offers a reasonable physics-based ionospheric background and is widely utilized in ionospheric *** use the TIEGCM simulations as the targeted ionosphere because the current measurements are far from able to realistically reproduce the ionosphere in *** designations of satellite measurements are conducted to investigate the limiting performance of CIT methods in ionospheric *** to common practice,electron density distributions from outputs of the International Reference Ionosphere(IRI)model are used as the iterative initial value in CIT *** outcomes suggest that despite data coverage,iterative initial conditions also play an essential role in ionospheric *** particular,in the longitudinal sectors where the iterative initial height of the F2-layer peak electron density(hmF2)differs substantially from the background densities,none of the three CIT methods can reproduce the exact background *** hmF2 is close but the ionospheric F2-layer peak density(NmF2)is different between the targeted background and initial conditions,the MART performs better than the ART and SIRT,as evidenced by the correlation coefficients of MART being above 0.97 and those of ART and SIRT being below *** summary,this investigation reveals the potential uncertainties in traditional CIT reconstruction,particularly when reali

关键词： computerized ionospheric tomography International Reference Ionosphere model Thermosphere Ionosphere Electrodynamics General Circulation model ionosphere

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Dipole tilt controls bow shock location and flaring angle

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Science China Earth Sciences 2017年第1期60卷 198-206页

作者： LU JianYong YUAN HuanZhi WANG Ming YANG YaFen Institute of space weather College of Math & StatisticsNanjing University of Information Science & Technology National Center for space weather China Meteorological Administration

The dipole tilt angle has beenfound to affect Earth's bow *** work presents a quantitative relationship between the dipole tilt angle and the bow shock location and flaring *** collected a large data set of bow shock crossings from four different satellites(IMP 8,Geotail,Magion 4,and Cluster),including some recent crossings obtained during *** results from a statistical analysis demonstrate that:(1)the subsolar standoff distance increases but the flaring angle decreases with increasing dipole tilt angle;(2)when the dipole tilt angle changes sign from negative to positive,the dayside bow shock moves toward Earth and the shift can be as much as 2.29 R_E,during which the flaring angle increases;and(3)the shape of bow shock in the northern and southern hemispheres *** the northern hemisphere bow shock,with increasing positive/negative dipole tilt angle,the flaring angle increases/*** for the southern hemisphere,the trend is the opposite;with increasing positive/negative dipole tilt angle,the flaring angle decreases/*** results are helpful for future bow shock modeling that needs to include the effects of dipole tilt angle.

关键词： Bow shock Dipole tilt Solar wind-magnetosphere coupling

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A study on the dynamic spectral indices for SEP events on 2000 July 14 and 2005 January 20

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Research in Astronomy and Astrophysics 2020年第3期20卷 129-135页

作者： Ming-Xian Zhao Gui-Ming Le Key laboratory of space weather National Center for Space WeatherChina Meteorological Administration.Beijing 100081China

We have studied the dynamic proton spectra for the two solar energetic particle(SEP)events on2000 July 14(hereafter GLE59)and 2005 January 20(hereafter GLE69).The source locations of GLE59 and GLE69 are N22 W07 and N12 W58 *** fluxes>30 Me V have been used to compute the dynamic spectral indices of the two SEP *** results show that spectral indices of the two SEP events increased more swiftly at early times,suggesting that the proton fluxes>30 Me V might be accelerated particularly by the concurrent flares at early times for the two SEP *** the GLE69 with source location at N12 W58,both flare site and shock nose are well connected with the Earth at the earliest ***,only the particles accelerated by the shock driven by eastern flank of the CME can propagate along the interplanetary magnetic field line to the Earth after the *** the GLE59 with source location at N22 W07,only the particles accelerated by the shock driven by western flank of the associated CME can reach the Earth after the *** results also show that there was slightly more than one hour during which the proton spectra for GLE69 are softer than that for GLE59 after the flares,suggesting that the shock driven by eastern flank of the CME associated with GLE69 is weaker than the shock driven by the western flank of the CME associated with *** results support that quasi-perpendicular shock has stronger potential in accelerating particles than the quasi-parallel *** results also suggest that only a small part of the shock driven by western flank of the CME associated with the GLE59 is quasi-perpendicular.

关键词： Sun:flares-Sun coronal mass ejections(CMEs)-Sun particle emission-Sun solarterrestrial relations

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Comparative analyses of current three-dimensional numerical solar wind models

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Science China Earth Sciences 2015年第6期58卷 839-858页

作者： Shi Tsan WU Murray DRYER Center for space Plasma and Aeronomic Research the University of Alabama in Huntsville space weather Predictions Center National Weather Service National Oceanic and Atmospheric Administration

We present a comparative study of the most advanced three-dimensional time-dependent numerical simulation models of solar wind. These models can be classified into two categories：（I） theoretical, empirical and numerically based models and （Ⅱ） self-consistent multi-dimensional numerical magnetohydrodynamic （MHD） models. The models of Category I are used to sep- arately describe the solar wind solution in two plasma flows regions： transonic/trans-Alfvrnic and supersonic/super-Alfvenic, respectively. Models of Category II construct a complete, single, numerical solar wind solution through subsonic/sub-Alfvrnic region into supersonic/super-Alfvrnic region. The Wang-Sheeley-Arge （WSA）/ENLIL in CISM is the most successful space weather model that belongs to Category I, and the Block-Adaptive-Tree-Solarwind-Roe-Upwind-Scheme （BATS-R-US） code in SWMF （space weather Modeling Framework） and the solar-interplanetary conservative element solution element MHD （SIP-CESE MHD） model in SWIM （space weather Integrated Model） are the most commonly-used models that belong to Category II. We review the structures of their frameworks, the main results for solar wind background studies that are essential for solar transient event studies, and discuss the common features and differences between these two categories of solar wind models. Finally, we conclude that the transition of these two categories of models to operational use depends on the availability of computational resources at reasonable cost and point out that the models＇ prediction capabilities may be improved by employing finer computational grids, incorporating more observational data and by adding more physical constraints to the models.

关键词： space weather solar wind models comparative analyses

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GPU-accelerated computing of three-dimensional solar wind background

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Science China Earth Sciences 2013年第11期56卷 1864-1880页

作者： FENG XueShang ZHONG DingKun XIANG ChangQing ZHANG Yao SIGMA weather Group State Key Laboratory for Space Weather Center for Space Science and Applied ResearchChinese Academy of Sciences

High-performance computational models are required to make the real-time or faster than rea^-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 so- lar 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 evolu- tion of the global structures for two Carrington rotations 2058 and 2062 is compared with solar observations and solar wind measurements t^om 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.

关键词： space weather modeling SIP-CESE MHD model GPU computing

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A New Hybrid Numerical Scheme for Two-Dimensional Ideal MHD Equations

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Chinese Physics Letters 2012年第9期29卷 101-104页

作者： ZHOU Yu-Fen FENG Xue-Shang SIGMA weather Group State Key Laboratory for Space WeatherCenter for Space Science and Applied ResearchChinese Academy of SciencesBeijing 100190

We present a new hybrid numerical scheme for two-dimensional(2D)ideal magnetohydrodynamic(MHD)equations.A simple conservation element and solution element(CESE)method is used to calculate the flow variables,and the unknown first-order spatial derivatives involved in the CESE method are computed with a finite volume scheme that uses the solution of the derivative Riemann problem with limited reconstruction to evaluate the numerical flux at cell interface *** show the validation and capacity of its application to 2D MHD problems,we study several benchmark *** results verify that the hybrid scheme not only performs well,but also can retain the solution quality even if the Courant number ranges from close to 1 to less than 0.01.

关键词： scheme element verify

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Numerical study of magnetic reconnection process near interplanetary current sheet

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Chinese Science Bulletin 2001年第2期46卷 111-117页

作者： Fengsi Wei Qiang Hu Xueshang Feng Ctr space Sci & Appl Res Lab Space Weather Beijing 100080 Peoples R China

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.

关键词： interplanetary space current sheet magnetic recon-nection numerical simulation.

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An improved CESE method and its application to steady-state coronal structure simulation

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Science China Earth Sciences 2014年第1期57卷 153-166页

作者： ZHOU YuFen FENG XueShang SIGMA weather Group State Key Laboratory for Space Weather Center for Space Science and Applied ResearchChinese Academy of Sciences

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)*** improved CESE method can improve the solution quality even with a large disparity in the Courant number(CFL)when using a fixed global marching ***,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 *** meanwhile,comparison with the original CESE scheme shows better resolution of the improved scheme ***,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.

关键词： improved CESE scheme numerical dissipation steady-state coronal structure

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