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| 1 | Modeling 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 | 2012 | Science China(Technological Sciences)2012，55，5： | 15 |
| 2 | The 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 | 2012 | Science China(Technological Sciences)2012，55，5： | 15 |
| 3 | A 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 | 2012 | Science China(Technological Sciences)2012，55，5： | 12 |
| 4 | Interferometry observations of low-latitude E-region irregularity patches using the Sanya VHF radar显示文摘Interferometry plays an important role in revealing fine-scale structures of ionospheric irregularity.By placing an additional receiving array of four 5-element Yagi antennas in the north of the main East-West array of the Sanya VHF radar,multiple interferometry baselines with components parallel and perpendicular to the magnetic meridian are formed.These baselines allow us to study the three-dimensional(3D)behavior of low-latitude ionospheric field-aligned irregularity(FAI)over Sanya.Using multiple non-collinear receiving baselines,an experiment for which the Sanya VHF radar operated as an interferometer was performed on 10 July 2013.Ionospheric E-region FAI echoes with periods of several minutes were observed during 0745-0915 UT;mean Doppler velocity was around -30 m/s with spectral widths of about 50 m/s.The interferometry results show fine-scale structures of E-region FAI with a zonal scale size of 15 km or less.In addition,we found that the periodic variations of echo intensity shown in radar range-time-intensity(RTI)maps were produced by spatially separated E-region irregularity patches.The patches drifted westward with a velocity of about 40-60 m/s and could be associated with propagating gravity waves.These results provide a clearer picture of the characteristics of FAI and thus help to investigate the generation and dynamics of low-latitude ionospheric irregularities in the Chinese sector. | LI GuoZhu NING BaiQi HU LianHuan | 2014 | Science China(Technological Sciences)2014，57，8： | 10 |
| 5 | Meteor radar observation of circulation near mesopause over Wuhan显示文摘The Wuhan meteor radar is the first all-sky meteor radar in China. The circulation near the mesopause from February to September 2002 is studied based on the data obtained by the Wuhan meteor radar. The zonal wind is usually eastward in winter from 80 to 100 km. The mean zonal wind become westward from March to early of May, when the winter circulation reverses to the summer circulation. But at the meteor heights, the zonal circulation usually becomes eastward after the middle of May. The meridional circulation is always equatorward. The peaks of the meridional wind move downward with the height, and the peak value reaches its maximum of 21 ms-1 in July. Having made a comparison between monthly mean wind and HWM93 model wind, the value of southward wind, the maximal value of eastward wind as well as the reversal height of zonal wind are found to be quite different from each other. | XIONG Jiangang, WAN Weixin, NING Baiqi & LIU Libo Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China Correspondence should be addressed to Xiong Jiangang (e-mail: xjg@wipm.ac.cn) | 2003 | Chinese Science Bulletin2003，48，15： | 8 |
| 6 | Seasonal 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 | 2012 | Science China(Technological Sciences)2012，55，5： | 3 |
| 7 | Preliminary 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 | 2020 | Earth and Planetary Physics2020，4，6： | 3 |
| 8 | The possibility of using all-sky meteor radar to observe ionospheric E-region field-aligned irregularities显示文摘All-sky meteor radars are primarily used for meteor observations. This paper reports the first observations of ionospheric Eregion field-aligned irregularities(FAIs) from a conventional all-sky meteor radar located at Wuhan(31°N, 114°E) for the period of March–June 2018. E-region FAI echoes evident in range-time intensity(RTI) maps show quasiperiodic striations with positive and negative slopes, which are consistent with multiple FAI structures moving across the wide beam of the meteor radar. A statistical analysis shows that out of a total of 111 d, there are 73 d with E-region FAI echoes detected by the meteor radar. The FAI events correspond well with the presence of sporadic-E layers which provide the necessary plasma density gradient for the development of gradient drift instability producing FAIs. The results demonstrate the capability of conventional meteor radars to make simultaneous routine observations of meteors and ionospheric E-region FAIs through incorporating RTI and spectral analysis into the online realtime data processing. Meteor radar observations could potentially address the limitations of ionospheric radars, which cannot provide simultaneous measurements of neutral winds and irregularity structures, and thereby contribute to better understanding of the dynamical processes producing E-region irregularities. | XIE HaiYong LI GuoZhu NING BaiQi REID Iain HU LianHuan WU BaoYuan YU You YANG SiPeng | 2019 | Science China(Technological Sciences)2019，62，8： | 3 |
| 9 | First 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 | 2018 | Earth and Planetary Physics2018，2，1： | 3 |
| 10 | Applying 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 | 2007 | Chinese Science Bulletin2007，52，17： | 2 |
| 11 | Monitoring 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 | 2013 | Science China Earth Sciences2013，56，5： | 2 |
| 12 | TIME-IGGCAS model validation:Comparisons with empirical models and observations显示文摘The TIME-IGGCAS (Theoretical Ionospheric Model of the Earth in Institute of Ge- ology and Geophysics, Chinese Academy of Sciences) has been developed re- cently on the basis of previous works. To test its validity, we have made compari- sons of model results with other typical empirical ionospheric models (IRI, NeQuick-ITUR, and TItheridge temperature models) and multi-observations (GPS, Ionosondes, Topex, DMSP, FORMOSAT, and CHAMP) in this paper. Several conclu- sions are obtained from our comparisons. The modeled electron density and elec- tron and ion temperatures are quantitatively in good agreement with those of em- pirical models and observations. TIME-IGGCAS can model the electron density variations versus several factors such as local time, latitude, and season very well and can reproduce most anomalistic features of ionosphere including equatorial anomaly, winter anomaly, and semiannual anomaly. These results imply a good base for the development of ionospheric data assimilation model in the future. TIME-IGGCAS underestimates electron temperature and overestimates ion tem- perature in comparison with either empirical models or observations. The model results have relatively large deviations near sunrise time and sunset time and at the low altitudes. These results give us a reference to improve the model and enhance its performance in the future. | YUE XinAn WAN WeiXing LIU LiBo NING BaiQi ZHAO BiQiang ZHANG ManLian | 2008 | Science China(Technological Sciences)2008，51，3： | 2 |
| 13 | GPS detection of the coseismic ionospheric disturbances following the 12 May 2008 M7.9 Wenchuan earthquake in China显示文摘Here we report two cases of coseismic ionospheric disturbances observed through a GPS network in China after the great Wenchuan earthquake at 06:28 UT on 12 May,2008.One is detected 7.9 min after the earthquake and had an intensive'N'shape oscillated waveform with a pronounced amplitude of about 1 TECU,which propagates approximately southward to the distance about 1000 km with the horizontal phase velocity of 600±84 m/s and the period of 9.5±1.3 min.The other is detected8.5 min after the earthquake and has an oscillated waveform more like a positive pulse with an amplitude of about 0.5 TECU,which propagates eastward to the distance about 800 km with the horizontal phase velocity of 720±59 m/s and the period of7.4±0.8 min.These two coseismic ionospheric disturbances are caused by the acoustic gravity waves excited by partial transformation of the acoustic waves originated from the energy release of the earthquake,somewhere near the epicenter.The directional preferences of these two coseismic ionospheric disturbances may be associated with the oblique geomagnetic field lines and the background winds filtering effect. | SONG Qian DING Feng YU Tao WAN WeiXing NING BaiQi LIU LiBo ZHAO BiQiang | 2015 | Science China Earth Sciences2015，58，1： | 2 |
| 14 | Variability study of the crest-to-trough TEC ratio of the equatorial ionization anomaly around 120°E longitude显示文摘 | Man-Lian Zhang Weixing Wan Libo Liu Baiqi Ning | 2008 | Advances in Space Research2008，，11： | 1 |
| 15 | Properties of large-scale TIDs observed in central China显示文摘 | Tang Qiulin Wan Weixing Ning Baiqi | 2001 | Science in China SerA2001，31，： | 1 |
| 16 | Analysis of ionospheric scintillation spectra and TEC in the Chi- nese low latitude region 显示文摘 | LI Guozhu NING Baiqi YUAN Hong | 2007 | Earth Planets Space2007，59，： | 1 |
| 17 | Solar activity variations of the ionospheric peak electron density 显示文摘 | Libo Liu Weixing Wan Baiqi Ning | 2006 | Journal of Geophysical Research2006，，111： | 1 |
| 18 | Low latitude ionospheric effects near longitude 120°E during the great geomagnetic storm of july 2000显示文摘 | Libo Liu Weixing Wan Baiqi Ning Hong Yuan J. Y. Liu | 2002 | Science in China Series A: Mathematics2002，，1： | 1 |
| 19 | The sudden increase in ionospheric total electron content caused by the very intense solar flare on july 14, 2000显示文摘 | Weixing Wan Hong Yuan Libo Liu Baiqi Ning | 2002 | Science in China Series A: Mathematics2002，，1： | 1 |
| 20 | Analysis of ionospheric sintillation spectra and TEC in the Chinese low latitude region显示文摘 | LI Guozhu NING Baiqi YUAN Hong | 2007 | Earth Planets Space2007，59，4： | 1 |
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