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67篇 您的检索式:作者名="WeiXing Wan"
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1Solar activity effects of the ionosphere: A brief review显示文摘Solar radiation, which varies over multiple temporal scales, modulates remarkably the evolution of the ionosphere. The solar activity dependence of the ionosphere is a key and fundamental issue in ionospheric physics, providing information essential to understanding the variations in the ionosphere and its processes. Selected recent studies on solar activity effects of the ionosphere are briefly reviewed in this report. This report focuses on (1) observations of solar irradiance at X-ray and extreme ultraviolet wavelengths and the outstanding problems of solar proxies, in the view of ionospheric studies, (2) new findings and improved representations of the features of the solar activity dependence of ionospheric key parameters and the corresponding physical processes, (3) possible phenomena in the ionosphere under extremely high and low solar activity conditions that are unique, as indicated by historical solar datasets and the deep solar minimum of solar cycle 23/24, and (4) statistical studies and model simulations of the ionosphere response to solar flares. The above-mentioned studies provide new clues for comprehensively explaining basic processes in the ionosphere and improving the prediction capability of ionospheric models and related applications.LIU LiBo WAN WeiXing CHEN YiDing LE HuiJun 2011Chinese Science Bulletin2011,56,12:45
2Modeling the global ionospheric total electron content with empirical orthogonal function analysis显示文摘In the present work we model the global ionospheric total electron content (TEC) with the analysis of empirical orthogonal functions (EOF). The obtained statistical eigen modes, which makeup the modeled TEC, consist of two factors: the eigen vectors mapping TEC patterns at latitude and longitude (or local time LT), and the corresponding coefficients displaying the TEC variations in different time scales, i.e., the solar cycle, the yearly (annual and semiannual) and the diurnal universal time variations. It is found that the EOF analysis can separate the TEC variations into chief processes and the first two modes illustrate the most of the ionospheric climate properties. The first mode contains both the semiannual component which shows the semiannual ionospheric anomaly and the annual component which shows the annual or non-seasonal ionospheric anomaly. The second mode contains mainly the annual component and shows the normal seasonal ionospheric variation at most latitudes and local time sectors. The annual component in the second mode also manifests seasonal anomaly of the ionosphere at higher mid-latitudes around noontime. It is concluded that the EOF analysis, as a statistical eigen mode method, is resultful in analyzing the ionospheric climatology hence can be used to construct the empirical model for the ionospheric climatology.WAN WeiXing DING Feng REN ZhiPeng ZHANG ManLian LIU LiBo NING BaiQi 2012Science China(Technological Sciences)2012,55,5:15
3The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan显示文摘Sanya VHF radar (18.4°N, 109.6°E, dip latitude 12.8°N) at Hainan Island is the first coherent backscatter radar for sounding low-latitude ionospheric irregularities in the mainland of China. In this paper, we present the first results of low-latitude ionospheric E and F region irregularities using the radar data during the period from February 2009 to March 2010. The Doppler velocity of radar echoes from E region field aligned irregularities (FAIs) was about several tens of meters per second, while the Doppler spectral width was appreciably larger than the velocity, and could reach one hundred meters per second, indicating that the observed E region FAIs belonged to type 2 irregularities. The observations of range time intensity (RTI) maps of FAIs showed that E region irregularities most often occurred at night within the altitude range 85-115 km, and were rarely observed at afternoon hours. The percentage occurrence of E region FAIs maximized during spring months (Feb.-May) with a peak value over 80%. The heights at which the strongest echo related FAIs occurred were mainly around 100 km, lower than h'Es and the difference is mostly 10-20 km. December solstice seemed to be the minimum period of occurrence when the FAI echoes were commonly detected at a narrow altitude range 90-100 km. Moreover, simultaneous radar and GPS observations during spread F events in the pre-midnight hours of solar minimum revealed that significant GPS L band scintillations coincided with the appearance of F region plasma plume structures, which extended up to 450 km in altitude.NING BaiQi HU LianHuan LI GuoZhu LIU LiBo WAN WeiXing 2012Science China(Technological Sciences)2012,55,5:15
4A comparison of mesospheric winds measured by FPI and meteor radar located at 40N显示文摘In this paper, winds derived from OH Meinel 892.0 nm detection by an FPI (Fabry-Perot Interferometer) are compared with the simultaneous wind measurements from a meteor radar during April-May of 2010. The peak height of OH Meinel 892.0 nm is about 87 km. The variations of FPI wind at 87 km mostly have the similar track to meteor radar wind at 87 km, and the data values of FPI wind mainly fall into the range of meteor radar wind. However, there are still quantitative differences between the observations of the two systems. The best cross-correlation occurs in meridional winds from two systems in April of 2010. An obvious wave signal with 0.2 cycle/d frequency is found in meridional winds observed by both FPI and meteor radar.JIANG GuoYing XU JiYao YUAN Wei NING BaiQi WAN WeiXing HU LianHuan 2012Science China(Technological Sciences)2012,55,5:12
5Olivine-norite rock detected by the lunar rover Yutu-2 likely crystallized from the SPA-impact melt pool显示文摘Chang’E-4 landed in the South Pole-Aitken(SPA)basin,providing a unique chance to probe the composition of the lunar interior.Its landing site is located on ejecta strips in Von Karm´an crater that´possibly originate from the neighboring Finsen crater.A surface rock and the lunar regolith at 10 sites along the rover Yutu-2 track were measured by the onboard Visible and Near-Infrared Imaging Spectrometer in the first three lunar days of mission operations.In situ spectra of the regolith have peak band positions at 1 and 2μm,similar to the spectral data of Finsen ejecta from the Moon Mineralogy Mapper,which confirms that the regolith’s composition of the landing area is mostly similar to that of Finsen ejecta.The rock spectrum shows similar band peak positions,but stronger absorptions,suggesting relatively fresh exposure.The rock may consist of 38.1±5.4%low-Ca pyroxene,13.9±5.1%olivine and 48.0±3.1%plagioclase,referred to as olivine-norite.The plagioclase-abundant and olivine-poor modal composition of the rock is inconsistent with the origin of the mantle,but representative of the lunar lower crust.Alternatively,the rock crystallized from the impact-derived melt pool formed by the SPA-impact event via mixing the lunar crust and mantle materials.This scenario is consistent with fast-cooling thermal conditions of a shallow melt pool,indicated by the fine to medium-sized texture(<3 mm)of the rock and the SPA-impact melting model[Icarus 2012;220:730–43].Honglei Lin Zhiping He Wei Yang Yangting Lin Rui Xu Chi Zhang Meng-Hua Zhu Rui Chang Jinhai Zhang Chunlai Li Hongyu Lin Yang Liu Sheng Gou Yong Wei Sen Hu Changbin Xue Jianfeng Yang Jie Zhong Xiaohui Fu Weixing Wan Yongliao Zou 2020National Science Review2020,7,5:9
6A theoretical model for mid-and low-latitude ionospheric electric fields in realistic geomagnetic fields显示文摘The geomagnetic fields,which play important roles in the ionospheric dynamo,can greatly affect the global distribution of ionospheric electric fields,currents and other ionospheric electrodynamics phenomena.In the study of ionospheric electrodynamics phenomena,such as the longitudinal variations of ionospheric electric fields,the non-dipolar component of the geomagnetic fields must be taken into account.In this paper,we deduce a theoretical electric field model for ionospheric dynamo at mid-and low-latitude which adopt a modified magnetic apex coordinates system.In the new electric field model,the geomagnetic fields can be calculated from either the IGRF model or the dipole field model,and the neutral winds and conductivities are calculated based on empirical models.Then the dynamo equation for the electric potential is finally solved in terms of the line-by-line iteration method,and the ionospheric electric fields and currents are derived from the calculated potential.Our model can reproduce the main features of the ionospheric electrodynamics processes,so it will be a useful tool for the investigation of the upper atmosphere and ionosphere.REN ZhiPeng WAN WeiXing WEI Yong LIU LiBo YU Tao 2008Chinese Science Bulletin2008,53,24:7
7Development of a middle and low latitude theoretical ionospheric model and an observation system data assimilation experiment显示文摘On the basis of previous work, we develop a middle and low latitude theoretical ionospheric model in this paper, named Theoretical Ionospheric Model of the Earth in the Institute of Geology and Geophysics, Chinese Academy of Sciences (TIME-IGGCAS). TIME-IGGCAS solves the equations of mass continuity, motion and energy of electron and ions self-consistently and uses an eccentric dipole field approxima-tion to the Earth’s magnetic field. We combine the Eulerian and Lagrangian approaches in the model and take account of the plasma E×B drift velocity. Calculation results reveal that the model is steady and credible and can reproduce most large-scale features of ionosphere. By using TIME-IGGCAS, we carried out an observation system data assimilation experiment. Assimilation results show that the E×B drift velocity can be accurately estimated by ingesting the observed foF2 and hmF2 into the model ap-plying nonlinear least-square fit method. We suggest that this work is of great significance in the de-velopment of ionospheric data assimilation model to give better nowcast and forecast of ionosphere.YUE XinAn WAN WeiXing LIU LiBo LE HuiJun CHEN YiDing YU Tao 2008Chinese Science Bulletin2008,53,1:7
8Enhanced anti-sunward flow near local noon during a period of horizontal IMF and high solar wind velocity V_Y显示文摘It is believed that a southward interplanetary magnetic field (IMF) is mainly responsible for the energy input from solar wind into the magnetosphere.This paper presents an unusual case of strong anti-sunward plasma flow (up to 2 km/s) in the polar cap ionosphere and large cross-polar cap potential (CPCP) during a period of horizontal IMF (|BZ| < 2 nT) observed by both ACE (at the L1 point) and Geotail (on the dusk flank of the magnetosheath).The CPCP is even higher than that under preceding BZ ≈-23 nT.Furthermore,GOES8 observed that the magnetosheath field turns northward as the anti-sunward plasma flow and CPCP start to increase,which implies that the magnetosheath field interacting with the Earth's magnetopause has significantly rotated and differs from the IMF observed by ACE and Geotail.In accordance with previous theoretical work,we suggest that the magnetic field line draping produces a southward magnetosheath field and enhances anti-sunward plasma flow and the CPCP.WEI Yong ZONG QiuGang PU ZuYin WAN WeiXing LIU JianJun FU SuiYan SHI QuanQi 2011Chinese Science Bulletin2011,56,11:7
9Recent investigation on the coupling between the ionosphere and upper atmosphere显示文摘Scientific attention has recently been focused on the coupling of the earth's upper atmosphere and ionosphere. In the present work, we review the advances in this field, emphasizing the studies and contributions of Chinese scholars. This work first introduces new developments in the observation instruments of the upper atmosphere. Two kinds of instruments are involved: optical instruments(lidars, FP interferometers and all-sky airglow imagers) and radio instruments(MST radars and all-sky meteor radars). Based on the data from these instruments and satellites, the researches on climatology and wave disturbances in the upper atmosphere are then introduced. The studies on both the sporadic sodium layer and sporadic E-layer are presented as the main works concerning the coupling of the upper atmosphere and the low ionosphere. We then review the investigations on the ionospheric longitudinal structure and the causative atmospheric non-migrating tide as the main progress of the coupling between the atmosphere and the ionospheric F2-region. Regarding the ionosphere-thermosphere coupling, we introduce studies on the equatorial thermospheric anomaly, as well as the influence of the thermospheric winds and gravity waves to the ionospheric F2-region. Chinese scholars have made much advancement on the coupling of the ionosphere and upper atmosphere, including the observation instruments, data precession, and modeling, as well as the mechanism analysis.WAN WeiXing XU JiYao 2014Science China Earth Sciences2014,57,9:7
10Climatological analysis and modeling of the ionospheric global electron content显示文摘In this paper, we calculate the ionospheric global electron content (GEC) from the GPS TEC data along the geographic longitude 120°E during the period of 1996-2004, and investigate the relationship be- tween GEC and 10.7 cm solar radio flux F10.7 and its seasonal dependence with partial correlation analysis. Our results show that GEC is closely correlated with solar activity index F10.7 and is also re- lated with annual and semiannual variations. An empirical GEC model driven by those factors is then to examine the influences of different solar activity proxies for the model input. The results suggest that GEC mainly depends on solar activity and the seasonal variations; the latter is also modulated by solar activity. Furthermore, the magnitude of semiannual variation is a little greater than that of annual varia- tion. Our empirical GEC model is proved to be better than the model proposed by Afraimovich et al.SHE ChengLi WAN WeiXing XU GuiRong 2008Chinese Science Bulletin2008,53,2:6
11Correlation between ionospheric longitudinal harmonic components and upper atmospheric tides显示文摘There is strong correlation among the ionospheric longitudinal structures of wavenumber-3(WN3),wavenumber-4(WN4),and eastward-propagating diurnal tides with zonal wave numbers s = 2 and 3(DE2 and DE3) in the upper atmosphere.The total electron content derived from the Global Ionospheric Maps of the Jet Propulsion Laboratory is used to deduce the latitudinally total electron content(ITEC) in the low-latitude ionosphere,and TIDE/TIMED observations are employed to obtain zonal and meridian winds of the mesopause and lower thermosphere.Through Fourier transformation,various ionospheric longitudinal harmonic components and tidal patterns are derived from the ionospheric and upper-atmospheric observations,and we compare the annual/inter-annual variations in ionospheric harmonic components WN3 and WN4 with those in atmospheric tides(DE2 and DE3).It is found that the annual and inter-annual variations in WN3 and WN4 are consistent with those in DE2 and DE3 zonal wind components respectively,while they are inconsistent with those in the meridian components.We then decompose the harmonic components into 'tidal patterns',finding that the 'DE2' and 'DE3' patterns are the main parts of WN3 and WN4 respectively.Their annual and inter-annual variations are similar to those of atmospheric tidal patterns(DE2 and DE3).Complex correlation results show that correlation between the ionospheric 'DE2' in WN3 and the atmospheric tidal DE2 zonal wind component is quite strong in the Northern Hemisphere,while that between the ionospheric 'DE3' in WN4 and the atmospheric tidal DE3 zonal wind component is much stronger at low latitudes.At the same time,the contribution of the meridian wind component is very weak.Above all,the atmospheric tidal DE2 and DE3 patterns are important factors of the ionospheric WN3 and WN4 structures.MU WenFeng WAN WeiXing REN ZhiPeng XIONG JianGang 2010Chinese Science Bulletin2010,55,35:5
12A planetary perspective on Earth's space environment evolution显示文摘The planet Earth is an integrated system, in which its multi-spheres are coupled, from the space to the inner core. Whether the space environment in short to long terms has been controlled by the earth's interior process is contentious. In the past several decades,space weather and space climate have been extensively studied based on either observation data measured directly by man-made instruments or ancient data inferred indirectly from some historical medium of past thousands of years. The acquired knowledge greatly helps us to understand the dynamic processes in the space environment of modern Earth, which has a strong magnetic dipole and an oxygen-rich atmosphere. However, no data is available for ancient space weather and climate(>5 ka). Here, we propose to take the advantage of ' space-diversity' to build a ' generalized planetary space family', to reconcile the ancient space environment evolution of planet Earth from modern observations of other planets in our solar system. Such a method could also in turn give us a valuable insight into other planets' evolution.Yong Wei XinAn Yue ZhaoJin Rong YongXin Pan WeiXing Wan RiXiang Zhu 2017Earth and Planetary Physics2017,1,1:4
13Empirical modeling of ionospheric F2 layer critical frequency over Wakkanai under geomagnetic quiet and disturbed conditions显示文摘The hourly values of the ionospheric F2 layer critical frequency, foF2, recorded at Wakkanai ionosonde station (45.4°N, 141.7°E) have been collected to construct a middle-latitude single-station model for forecasting foF2 under geomagnetic quiet and disturbed conditions. The module for the geomagnetic quiet conditions incorporates local time, seasonal, and solar variability of climatological foF2 and its upper and lower quartiles. It is the first attempt to predict the upper and lower quartiles of foF2 to account for the notable day-to-day variability in ionospheric foF2. The validation statistically verifies that the model captures the climatological variations of foF2 with higher accuracy than IRI does. The storm-time module is built to capture the geomagnetic storm induced relative deviations of foF2 from the quiet time references. In the geomagnetically disturbed module, the storm-induced deviations are described by diurnal and semidiurnal waves, which are modulated by a modified magnetic activity index, the Kf index, reflecting the delayed responses of foF2 to geomagnetic activity forcing. The coefficients of the model in each month are determined by fitting the model formula to the observation in a least-squares way. We provide two options for the geomagnetic disturbed module, including or not including Kalman filter algorithm. The Kalman filter algorithm is introduced to optimize these coefficients in real time. Our results demonstrate that the introduction of the Kalman filter algorithm in the storm time module is promising for improving the accuracy of predication. In addition, comparisons indicate that the IRI model prediction of the F2 layer can be improved to provide better performances over this region.LIU Jing LIU LiBo ZHAO BiQiang WAN WeiXing CHEN YiDing 2012Science China(Technological Sciences)2012,55,5:4
14Seasonal variations of night mesopause temperature in Beijing observed by SATI4显示文摘The data observed by a spectral airglow temperature imager (SATI) at Beijing National Observatory of Space Environment from July 23, 2008 to July 31, 2009 are used to study night mesopause temperature in Beijing. From variations of temperature at 87 and 94 km obtained from OH (6-2) and O2 (0-1) airglow spectra, temperature at night is shown lowest in the summer and highest in the winter. In summer, average temperature at 87 km is 173.9 K, lower than average temperature 180.1 K at 94 km. But in winter, average temperature at 87 km is 201.2 K, higher than average temperature 194.8 K at 94 km. The altitude of mesopause in Beijing is below 87 km in summer and above 94 km in winter. There are about 120-150 days when the mesopause locates below 87 km, which is in agreement with the results of SABER/TIMED. Variations of temperatures at 87 and 94 km are analyzed by harmonic method. Our results show that amplitudes of annual oscillation of temperature at 87 and 94 km are 17.5 and 7.8 K respectively. Amplitudes of semi-annual oscillation at 87 and 94 km are 1.6 and 5.3 K, which are smaller than those of annual oscil- lation. Although there are differences among different observations because of different locations and different instruments, our results are in general agreement with observation at similar latitude as Beijing.XIONG JianGang WAN WeiXing NING BaiQi LIU LiBo WU BaoYuan HU LianHuan XU Tao 2012Science China(Technological Sciences)2012,55,5:3
15Preliminary experimental results by the prototype of Sanya Incoherent Scatter Radar显示文摘In the past decades,the Incoherent Scatter Radar(ISR)has been demonstrated to be one of the most powerful instruments for ionosphere monitoring.The Institute of Geology and Geophysics at the Chinese Academy of Sciences was founded to build a state-ofthe-art phased-array ISR at Sanya(18.3°N,109.6°E),a low-latitude station on Hainan Island,named the Sanya ISR(SYISR).As a first step,a prototype radar system consisting of eight subarrays(SYISR-8)was built to reduce the technical risk of producing the entire large array.In this work,we have summarized the preliminary experimental results based on the SYISR-8.The amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring network.The mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°,respectively,which met the basic requirements.The beam directivity was confirmed by crossing screen of the International Space Station.The SYISR-8 was further used to detect the tropospheric wind profile and meteors.The derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS measurements.The SYISR-8 was able to observe several typical meteor echoes,such as the meteor head echo,range-spread trail echo,and specular trail echo.These results confirmed the validity and reliability of the SYISR-8 system,thereby reducing the technical risk of producing the entire large array of the SYISR to some extent.XinAn Yue WeiXing Wan Han Xiao LingQi Zeng ChangHai Ke BaiQi Ning Feng Ding BiQiang Zhao Lin Jin Chen Li MingYuan Li JunYi Wang HongLian Hao Ning Zhang 2020Earth and Planetary Physics2020,4,6:3
16The payloads of planetary physics research onboard China’s First Mars Mission (Tianwen-1)显示文摘Mars is not only our nearby but also the most Earth-like planetary neighbor.Scientific exploration of Mars is thus of crucial value to our understanding of the solar system.The existence of abundant evidence for the former presence of water on Mars demands further exploration for signs of life on our sister planet,and investigations that could shed light on conditions favorable to the origin of life.For nearly 60 years,humans have conducted orbitally-based remote sensing and in-situ surface exploration of Mars,leading to many significant scientific discoveries.But much remains to be done before we can be sure that we truly and fully understand Mars.Key research topics include the history of water on Mars and how that history relates to the planet’s habitable environment-past,present,and future;the distribution and evolution of waterbearing and evaporative salt minerals on the planet’s surface;the history of volcanic activity on Mars;the Martian magnetic field and its effect on the escape of water and atmosphere from the planet;interactions between the solar wind and the Martian atmosphere and ionosphere;atmospheric characteristics and climate change on Mars;and so on(Li CL et al.,2018;Liu JJ et al.,2018).Based on the above scientific questions about life,climate,and geology on Mars,the international planetary science community has formulated ambitious Mars exploration programs.WeiXing Wan Chi Wang ChunLai Li Yong Wei JianJun Liu 2020Earth and Planetary Physics2020,4,4:3
17Recent ionospheric investigations in China(2018–2019)显示文摘Since the release of the 2018 National Report of China on ionospheric research(Liu LB and Wan WX,2018)to the Committee on Space Research(COSPAR),scientists from China's Mainland have made many new fruitful investigations of various ionospheric-related issues.In this update report,we briefly introduce more than 130 recent reports(2018–2019).The current report covers the following topics:ionospheric space weather,ionospheric structures and climatology,ionospheric dynamics and couplings,ionospheric irregularity and scintillation,modeling and data assimilation,and radio wave propagation in the ionosphere and sounding techniques.LiBo Liu WeiXing Wan 2020Earth and Planetary Physics2020,4,3:3
18First results of optical meteor and meteor trail irregularity from simultaneous Sanya radar and video observations显示文摘Meteoroids entering the Earth's atmosphere can create meteor trail irregularity seriously disturbing the background ionosphere. Although numerous observations of meteor trail irregularities were performed with VHF/UHF coherent scatter radars in the past, no simultaneous radar and optical instruments were employed to investigate the characteristics of meteor trail irregularity and its corresponding meteoroid. By installing multiple video cameras near the Sanya VHF radar site, an observational campaign was conducted during the period from November 2016 to February 2017. A total of 242 optical meteors with simultaneous non-specular echoes backscattered from the plasma irregularities generated in the corresponding meteor trails were identified. A good agreement between the angular positions of non-specular echoes derived from the Sanya radar interferometer and those of optical meteors was found,validating that the radar system phase offsets have been properly calibrated. The results also verify the interferometry capability of Sanya radar for meteor trail irregularity observation. The non-specular echoes with simultaneous optical meteors were detected at magnetic aspect angles greater than ~78°. Based on the meteor visual magnitude estimated from the optical data, it was found that the radar nonspecular echoes corresponding to brighter meteors survived for longer duration. This could provide observational evidence for the significance of meteoroid mass on the duration of meteor trail irregularity. On the other hand, the simultaneous radar and video common-volume observations showed that there were some cases with optical meteors but without radar non-specular echoes. One possibility could be that some of the optical meteors appeared at extremely low altitudes where meteor trail irregularities rarely occur.GuoZhu Li BaiQi Ning Ao Li SiPeng Yang XiuKuan Zhao BiQiang Zhao WeiXing Wan 2018Earth and Planetary Physics2018,2,1:3
19Applying partial correlation method to analyzing the correlation between ionospheric NmF2 and height of isobaric level in the lower atmosphere显示文摘On the basis of a multiple linear regression model performed for ionospheric NmF2, partial correlation method is first applied to investigating the relation between NmF2 and h (the height of isobaric level) in the lower atmosphere over Wuhan, China during 1957―2004. The results show that partial correlation method can eliminate the influences of solar and geomagnetic activities as well as the seasonal varia- tion factors and reveal the true correlation between NmF2 and h in the lower atmosphere. A weak posi- tive correlation between NmF2 and h is found in the middle stratosphere. In addition, by comparing the partial correlation coefficients between NmF2 and its influence factors, we find that NmF2 is mainly affected by solar activity and the seasonal variation factors, and weakly affected by geomagnetic ac- tivity, but hardly affected by h in the lower atmosphere. The study suggests that partial correlation method is a helpful tool for investigating the correlation between ionospheric parameter and its influ- ence factors.XU GuiRong WAN WeiXing NING BaiQi 2007Chinese Science Bulletin2007,52,17:2
20Monitoring traveling ionospheric disturbances using the GPS network around China during the geomagnetic storm on 28 May 2011显示文摘Larger-scale traveling ionospheric disturbances (LSTIDs) are studied using the total electron content (TEC) data observed from 246 GPS receivers in and around China during the medium storm on 28 May 2011. It is the first attempt to get the two-dimensional TEC perturbation maps in China. Two LSTID events are detected: one is in southwestern China before midnight propagating from low to middle latitude to the distance of about 1200 km with the phase front extending to about 500 km, and the other is in northeastern China after midnight propagating from middle to low latitudes to the distance of about 1200 km with the phase front extending to nearly 1400 km. By using the multichannel maximum-entropy method, we get the propagation parameters of these two LSTIDs. The LSTID that occurs before midnight has a higher horizontal phase velocity and a larger damping rate corresponding to the after midnight LSTID, and this may be caused by the relatively large vertical background TEC 0 and high atmospheric temperature in the southwest of China before midnight. According to the variations of magnetic H component observed in high latitudes, the source region for the after midnight LSTID is likely to be located 1400-2600 km east of 140°E and north of 42°N; the before midnight LSTID is propably excited by the atmospheric gravity waves (AGWs) generated by the Joule heating of the equatorial electrojet.SONG Qian DING Feng WAN WeiXing NING BaiQi ZHAO BiQiang 2013Science China Earth Sciences2013,56,5:2
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