检索结果-南通市图书馆

Statistical characteristics of the equatorial boundary of the nightside auroral particle precipitation

Science China Earth Sciences 2015年第9期58卷 1602-1608页

作者： NIU YanYuan ZHANG XiaoXin HE Fei JIANG Yong Nanjing University of Information Science & Technology Key laboratory of space weather National Center for Space Weather China Meteorological Administration Changchun Institute of Optics Fine Mechanics and Physics Chinese Academy of Sciences

Based on the auroral electron/ion precipitation boundary database observed by the DMSP satellites during 1984–2009, the characteristics of the nightside equatorial boundaries of the electron precipitation（B1E） and the ion precipitation（B1I） in the Northern/Southern Hemispheres（NH/SH） are statistically investigated. The results show： That most of the boundaries are located between magnetic latitude（MLAT） of 60°–70° with the mean MLAT for B1E/B1 I to be 64.30°N/63.22°N and 64.48°S/63.26°S in the NH and SH, respectively, indicating that B1 E and B1 I in both hemispheres are located in conjugated magnetic field lines with B1 E ~1.2° poleward of B1I; that the MLAT of B1 E and B1 I in both hemispheres shift to lower MLAT（from ~70° to ~55°） as geomagnetic activity increases; that MLAT of both B1 E and B1 I and their differences slowly decrease from dusk to midnight with some difference in both hemispheres during different levels of geomagnetic activities; that B1 E and B1 I in both hemisphere decrease linearly with Kp and exponentially with Dst, AE, and SYM-H, respectively, demonstrating that auroral particle precipitation is closely related with geomagnetic activity; that in different magnetic local time（MLT） sectors, the changing rates of the boundaries with Kp are different, and the rates of B1 E are generally larger than that of B1 I, implying that the difference between B1 E and B1 I reduce with increasing geomagnetic activity. Compared with previous studies, the statistical results based on the long-term large database in this paper can well reflect the properties of the equatorial boundaries of auroral precipitation and may be used for physical modeling or space weather forecasting in future.

关键词： auroral particle precipitation equatorial boudanry statistical characteristics geomagnetic activity

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

An empirical model of the global distribution of plasmaspheric hiss based on Van Allen Probes EMFISIS measurements

引用

Earth and Planetary Physics 2020年第3期4卷 246-265页

作者： JingZhi Wang Qi Zhu XuDong Gu Song Fu JianGuang Guo XiaoXin Zhang Juan Yi YingJie Guo BinBin Ni Zheng Xiang Department of space Physics School of Electronic InformationWuhan UniversityWuhan 430079China Key laboratory of space weather National Center for Space WeatherChina Meteorological AdministrationBeijing 100081China

Using wave measurements from the EMFISIS instrument onboard Van Allen Probes,we investigate statistically the spatial distributions of the intensity of plasmaspheric hiss *** reproduce these empirical results,we establish a fitting model that is a thirdorder polynomial function of L-shell,magnetic local time(MLT),magnetic latitude(MLAT),and AE*.Quantitative comparisons indicate that the model’s fitting functions can reflect favorably the major empirical features of the global distribution of hiss wave intensity,including substorm dependence and the MLT *** results therefore provide a useful analytic model that can be readily employed in future simulations of global radiation belt electron dynamics under the impact of plasmaspheric hiss waves in geospace.

关键词： hiss Van Allen Probes global model

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Tilt of the ring current during the main phases of intense geomagnetic storms

引用

Science China(Technological Sciences) 2019年第5期62卷 820-828页

作者： LIU BaoJia ZHANG XiaoXin HE Fei Institute of space weather School of Math & Statistics Nanjing University of Information Science & Technology State Key laboratory of Severe weather Chinese Academy of Meteorological SciencesChina Meteorological Administration Key laboratory of space weather National Center for Space Weather China Meteorological Administration Key laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Institutions of Earth Science Chinese Academy of Sciences College of Earth and Planetary Sciences University of Chinese Academy of Sciences

Based on the data from the SuperMAG collaboration in 2000–2014, the magnetic latitude(MLAT) location of the ring current(RC) denoted by the MLAT of the maximum horizontal magnetic disturbance during the main phase of 67 intense geomagnetic storms(Dst ≤-100 nT) are derived. The results show that the maximum horizontal magnetic disturbance does not always occur in the magnetic equator, indicating that the RC might be tilted in the latitudinal direction during these storms. Specifically, the tilt of the RC near the day-night line is affected by the direction of solar wind. When the solar wind flows southward against the magnetic equatorial plane, the RC is more likely to show a dayside-lifted tilt. When the solar wind flows northward, the pattern is opposite. Tilts of the RC near the dawn-dusk line are also found in most of these storms. The location of the RC is mainly lifted in the dusk side and declined in the dawn side for positive IMF BY, while the tilt is reversed for negative IMF BY. A possible interpretation might be the IMF BY-related twisting of the geomagnetic field. Besides, the monthly averaged MLAT of the fitted RC also varies with seasons. It is shifted to the southern hemisphere in the northern summer and to the northern hemisphere in the northern winter, which might indicate that the RC is not centered on a single plane. Such a seasonal variation might be related to the angle between the solar wind and the magnetic equatorial plane.

关键词： tilt of ring current geomagnetic storm solar wind interplanetary magnetic field

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

3D MHD simulation of the double-gradient instability of the magnetotail current sheet

引用

Science China(Technological Sciences) 2018年第9期61卷 1364-1371页

作者： DUAN AiYing ZHANG Huai LU Hao Yu Key laboratory of Computational Geodynamics University of Chinese Academy of Sciences State Key laboratory of space weather Chinese Academy of Sciences School of space and Environment Beihang University

Flapping motion of the current sheet(CS) is an important physical process in the Earth's magnetotail. The magnetic doublegradient model, which includes both the instability and wave modes, offers a reasonable explanation for the exciting and propagation of the flapping wave. In this paper, we apply an advanced numerical magnetohydrodynamic(MHD) scheme(conservation element and solution element(CESE)-MHD) to simulate the magnetic double-gradient instability in an idealized current sheet that mimics the magnetotail configuration. We initialize the simulations with a numerically relaxed magnetotail equilibrium, in which the normal component of the magnetic field has a tailward gradient. It is confirmed in our simulation that the instability develops in the current layer. The growth rate of the instability yielded from the simulation is very close to the prediction of theory, with a relative deviation of only ten percent. The results demonstrate that the CESE-MHD scheme is very powerful in numerical study of the double-gradient mechanism of the CS flapping mode, and can be used for further investigations of the flapping motion in more realistic CS configurations.

关键词： Earth's magnetotail current sheet flapping magnetohydrodynamic numerical simulation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Prediction tests by using ISF method for the geomagnetic disturbances

引用

Science China(Technological Sciences) 2002年第5期45卷 525-530页

作者：魏奉思徐亚冯学尚范全林 Key laboratory of space weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China

A so-called ISF method for predicting geomagnetic disturbances caused by solar wind storm blowing to the earth is suggested. The method is based on a combined approach to solar activity, interplanetary scintillation (IPS) and geomagnetic disturbance observations in 1966-1982, dynamics of disturbance propagation and fuzzy mathematics. Prediction test has been made for 24 large geomagnetic disturbance events that produced space disasters during the period of 1980-1998, with the three-dimensional propagation characteristics, the best close degree of each radio source and the influence of the south-north components of interplanetary magnetic fields considered. The main results are (I) for onset time of the geomagnetic disturbance, events with relative error △Tpred/Tobs≤10% between the observation Tobs and the prediction Tpred, account for 45.8% of all events, ≤30% for 78.3% and >30% for only 21.7%; (ii) as for the magnetic disturbance magnitude, events with relative error △∑Kp,pred/∑Kp,obs≤10% between the observation ∑Kp,obs and the prediction ∑Kp,pred, account for 41.6% of all events, ≤30% for 79% and ≤45% for 100%. For example, the prediction test of April-May event in 1998 indicates that △Tpred/Tobs=7.4%, △∑Kp,pred/∑Kp,obs=15.3%. Our result shows that the prediction method suggested in this paper has encouraging prospects in improving geomagnetic disturbance prediction in space weather events.

关键词： space weather, geomagnetic disturbance prediction, IPS observation.

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Preprocessing photospheric vector magnetograms for nonlinear force-free field extrapolation of the global corona

引用

Research in Astronomy and Astrophysics 2018年第7期18卷 113-124页

作者： Ai-Ying Duan Huai Zhang Key laboratory of Computational Geodynamics University of Chinese Academy of Sciences SIGMA weather Group State Key Laboratory for Space Weather National Space Science Center Chinese Academy of Sciences laboratory for Marine Mineral Resources Qingdao National Laboratory for Marine Science and Technology

Nonlinear force-free magnetic field （NLFFF） extrapolation based on the observed photo- spheric magnetic field is the most important method to obtain the coronal magnetic field nowadays. However, raw photospheric magnetograms contain magnetic forces and small-scale noises, and fail to be consistent with the force-free assumption of NLFFF models. The procedure for removing the forces and noises in observed data is called preprocessing. In this paper, we extend the preprocessing code of Jiang ＆ Feng to spherical coordinates for a full sphere. We first smooth the observed data with Gaussian smoothing, and then split the smoothed magnetic field into a potential field and a non-potential field. The potential part is computed by a numerical potential field model, and the non-potential part is prepro- cessed using an optimization method to minimize the magnetic forces and magnetic torques. Applying the code to synoptic charts of the vector magnetic field from SDO/HMI, we find it can effectively reduce the noises and forces, and improve the quality of data for a better input which will be used for NLFFF extrapolations applied to the global corona.

关键词： magnetic fields - magnetohydrodynamics (MHD) - methods numerical - Sun corona

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Relationship between CME velocities and X-ray fluxes of associated flares

引用

Chinese Journal of Astronomy and Astrophysics 2009年第4期9卷 470-474页

作者： An-Qin Chen Wei-Guo Zong National Center for space weather China Meteorological Administration Beijing 100081 China State Key laboratory of space weather Chinese Academy of Sciences Beijing 100080 China

Coronal mass ejection （CME） velocities have been studied over recent decades. We present a statistical analysis of the relationship between CME velocities and X-ray fluxes of the associated flares. We study two types of CMEs. One is the FL type associated only with flares, while the other is the intermediate type associated with both filament eruptions and flares. It is found that the velocities of the FL type CMEs are strongly correlated with both the peak and the time-integrated X-ray fluxes of the associated flares. However, the correlations between the intermediate type CME velocities and the corre- sponding two parameters are poor. It is also found that the correlation between the CME velocities and the peak X-ray fluxes is stronger than that between the CME velocities and the time-integrated X-ray fluxes of the associated flares.

关键词： Sun coronal mass ejections (CMEs)-Sun flares-Sun filaments

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Particle bursts in the inner radiation belt related to global lightning activity

引用

Science China(Technological Sciences) 2013年第11期56卷 2658-2667页

作者： WU Fei HAO YongQiang ZHANG DongHe Institute of space Physics and Applied Technology Peking University State Key laboratory of space weather Chinese Academy of Sciences

Particle bursts （PBs）, the phenomena characterized by short-term increases of particle counting rates （CRs）, were observed by space-borne radiation belt particle detectors. With the electron CR data obtained by National Oceanic and Atmospheric Ad- ministration （NOAA）-18 satellite, the occurrence of PBs in the inner belt （I〈~L〈2 and B〉20.5 gT） were derived for years 2006-2011. The monthly occurrence number of PBs exhibits a strong maximum in northern summer （May-August）. In associ- ation with global lightning data, the seasonal occurrence of PBs is found to be consistent with the lightning activity, especially if only lightning flashes at latitudes 〉20~ are taken into account. The positive correlation between PBs and mid-latitude light- ning discharges indicates the role of lightning-induced whistler waves, and is consistent with the expected pitch-angle scatter- ing by wave-particle interactions. The contribution of lightning is so significant that it forms a non-negligible seasonal back- ground of PBs. If one connects PBs to seismoelectromagnetic emissions （SEME） in attempt to find the earthquake precursor, the lightning background needs to be considered with great care.

关键词： particle burst (PB) wave-particle interaction lightning-induced VLF seismo-electromagnetic emissions (SEME)

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Imaging energetic electron spectrometer onboard a Chinese navigation satellite in the inclined GEO orbit

引用

Science China(Technological Sciences) 2018年第12期61卷 1845-1865页

作者： ZOU Hong YE YuGuang ZONG QiuGang CHEN HongFei ZOU JiQing CHEN Jiang SHI WeiHong YU XiangQian ZHONG WeiYing WANG YongFu ZHOU XuZhi HAO YiXin CHEN XingRan JIA XiangHong XU Feng SHAO SiPei WANG Bo HAO XiaoYun ZHANG XiaoXin Institute of space Physics and Applied Technology Peking University Beijing 100871 China State Key laboratory of space Medicine Fundamentals and Application Chinese Astronaut Research and Training Center Beijing 100094 China Shandong Aerospace Electro-technology Yantai 264000 China Key laboratory of space weather National Center for Space Weather Beijing 100081 China

The energetic electron measurement is one of the most important issues to understand dynamics in space physics and the applications for space weather. In this study, the principle and functional components of the imaging energetic electron spectrometer(IES) onboard a Chinese navigation satellite in the inclined GEO orbit(IGSO) was introduced. The IES instrument is developed by the team in Peking University(BeiDa), thus it is named as BD-IES. Based on the pin-hole technique, the instrument can measure 50–600 keV electrons incident from 9 directions over a range of 180° in polar angle. With pulse height analysis(PHA), the spectrum can be determined for each direction. The energy and angular calibrations were performed, which show the good energy and angular characteristics of BD-IES. Monte Carlo simulations show that the anti-proton design of BDIES can effectively decrease the proton contamination on the electron measurements in the inclined GEO orbit. The primary results of BD-IES verify the successful design of this instrument.

关键词： imaging energetic electron spectrometer pin-hole imaging system IGSO satellite

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Modeling Density and Anisotropy of Energetic Electrons Along Magnetic Field Lines

引用

Plasma Science and Technology 2006年第3期8卷 279-284页

作者：肖伏良冯学尚 Department of Physics and Electronic Sciences Changsha University of Science and Technology Changsha 410076 China State Key Laboratory of Space Weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China State Key laboratory of space weather Center for Space Science and Applied Research Chinese Academy of Sciences Beijing 100080 China

The electromagnetic wave growth or damping depends basically on the number density and anisotropy of energetic particles as the resonant interaction takes place between the particles and waves in the magnetosphere. The variance of both the number density and anisotropy along the magnetic field line is evaluated systematically by modeling four typically prescribed distribution functions. It is shown that in the case of ＂the positive anisotropy＂（namely, the perpendicular temperature T⊥ exceeds the parallel temperature T｜｜）, the number density of energetic electrons always decreases with the magnetic latitude for a regular increasing magnetic field and the maximum wave growth is therefore generally confined to the equator where the resonant energy is minimum, and the number density is the largest. However, the ＂loss-cone＂ anisotropy of the electrons with a ＂pancake＂ distribution or kappa distribution keeps invariant or nearly invariant, whereas the ＂temperature＂ anisotropy with a pure bi-Maxwellian distribution or Ashour-Abdalla and Kennel＇s distributions decreases with the magnetic latitude. The results may provide a useful approach to evaluating the number density and anisotropy of the energetic electrons at latitudes where the observation information is not available.

关键词： number density anisotropy distribution function magnetic field line

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：