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First results of optical meteor and meteor trail irregularity from simultaneous Sanya radar and video observations

Earth and Planetary Physics 2018年第1期2卷 15-21页

作者： GuoZhu Li baiqi ning Ao Li SiPeng Yang XiuKuan Zhao BiQiang Zhao WeiXing Wan Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Institutions of Earth Science Chinese Academy of SciencesBeijing 100029China Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China University of Chinese Academy of Sciences Beijing 100049China

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.

关键词： meteor ionosphere radar non-specular echo

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Preliminary experimental results by the prototype of Sanya Incoherent Scatter Radar

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Earth and Planetary Physics 2020年第6期4卷 579-587页

作者： 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 Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy for Earth Science Chinese Academy of SciencesBeijing 100029China Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049China Nanjing Research Institute of Electronics Technology Nanjing 210039China

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.

关键词： incoherent scatter radar SYISR ionosphere phased array beam direction tropospheric wind meteor

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Interferometry observations of low-latitude E-region irregularity patches using the Sanya VHF radar

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Science China(Technological Sciences) 2014年第8期57卷 1552-1561页

作者： LI GuoZhu ning baiqi HU LianHuan Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences

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.

关键词：米波雷达干涉仪低纬度三亚补丁固定资产投资低纬电离层 VHF雷达

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Applying partial correlation method to analyzing the correlation between ionospheric NmF2 and height of isobaric level in the lower atmosphere

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Chinese Science Bulletin 2007年第17期52卷 2413-2419页

作者： XU GuiRong WAN WeiXing ning baiqi Institute of Geoloqy and Geophysics Chinese Academy of Sciences Beijing 100029 China Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

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.

关键词：低层大气偏相关方法线性回归模型电离层

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An Effective Active Semi-supervised Learning Method Based on Manifold Regularization

An Effective Active Semi-supervised Learning Method Based on...

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中国科学院地质与地球物理研究所2013年度（第13届）...

作者： Xiukuan Zhao baiqi ning Gangbing Song Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences Department of Mechanical Engineering University of Houston

Conventional artificial intelligent methods such as neural network and SVM use only labeled data (feature/label pairs) for training.Labeled instances are often difficult,expensive,or time consuming to obtain. To use a large amount of unlabeled data together with labeled data to build better models,we proposed an active semi-supervised learning method based on the pool query active learning and mamfold regularization semi-supervised method.In this paper,the effectiveness of the method was verified by its application to a synthetic data set and three real world classification problems.The experimental results showed that employing our active semi-supervised learning method can significantly reduce the need for labeled training instances.

关键词： Semi-supervised learning active learning LapSVM A-LapSVM

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The first time observations of low-latitude ionospheric irregularities by VHF radar in Hainan

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Science China(Technological Sciences) 2012年第5期55卷 1189-1197页

作者： ning baiqi HU LianHuan LI GuoZhu LIU LiBo WAN WeiXing Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Beijing National Observatory of Space Environment Beijing 102213China Graduate University of Chinese Academy of Sciences Beijing 100081China

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.

关键词： VHF雷达观测过程电离层低纬度海南岛多普勒速度违规行为等离子体羽

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An investigation of the formation patterns of the ionospheric F3 layer in low and equatorial latitudes

An investigation of the formation patterns of the ionospheri...

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中国科学院地质与地球物理研究所2013年度（第13届）...

作者： Jie Zhu Biqiang Zhao Weixing Wan baiqi ning Key Laboratory of Ionospheric Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences China University of Chinese Academy of Sciences

lonogram traces with the F3 layer in different latitude do not always seem similar.In our work,we tend to describe morphological features of traces with the F3 layer in magnetic low-latitude region and near magnetic equator through the quantitative investigation of the diurnal variation and latitude dependence of two morphologically characteristic parameters - the foF2-to-foF3 ratio and the difference between h’F3 and h’F2 - in geomagnetically quiet period.The distribution of two formation patterns (pattern A and pattern B are defined with increasing F3 peak density and with nearly constant or decreasing F3 peak density respectively as the peak moving upward around the onset of the F3 layer’s occurrence) of the F3 layer is also investigated based on statistics of formation patterns of the F3 layer in Sanya and Kwajalein in 2011.The ideal equinoctial distribution(without the summer-to-winter neutral wind) of those patterns is symmetrical about magnetic equator with pattern A in magnetic low-latitude region and pattern B near magnetic equator.When taking the summer-to-winter neutral wind which resists(enhances) the plasma diffusion to higher latitude in the windward(leeward) into consideration in a solstice,pattern A could be observed near magnetic equator in summer hemisphere and pattern B in magnetic low-latitude region in winter hemisphere compared with the ideal distribution in the equinox.

关键词： Ionosphere Low latitude F3 layer

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Modeling the global ionospheric total electron content with empirical orthogonal function analysis

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Science China(Technological Sciences) 2012年第5期55卷 1161-1168页

作者： WAN WeiXing DING Feng REN ZhiPeng ZHANG ManLian LIU LiBo ning baiqi Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

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.

关键词：经验正交函数分析电离层异常电子总含量建模 EOF分析高纬度地区时间尺度太阳活动周期

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GPS detection of the coseismic ionospheric disturbances following the 12 May 2008 M7.9 Wenchuan earthquake in China

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Science China Earth Sciences 2015年第1期58卷 151-158页

作者： SONG Qian DING Feng YU Tao WAN WeiXing ning baiqi LIU LiBo ZHAO BiQiang National Center for Space Weather China Meteorological Administration Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences

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.

关键词：电离层扰动 GPS网大地震中国汶川测震能量释放过滤效果

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A prediction model of short-term ionospheric fo F2 based on Ada Boost

A prediction model of short-term ionospheric fo F2 based on ...

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中国科学院地质与地球物理研究所2014年度（第14届）...

作者： Xiukuan Zhao baiqi ning Libo Liu Gangbing Song Key Laboratory of Ionospheric Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences Department of Mechanical Engineering University of Houston School of Civil Engineering Dalian University of Technology

In this paper, the Ada Boost-BP algorithm is used to construct a new model to predict the critical frequency of the ionospheric F2-layer(fo F2) one hour ahead. Different indices were used to characterize ionospheric diurnal and seasonal variations and their dependence on solar and geomagnetic activity. These indices, together with the current observed fo F2 value, were input into the prediction model and the fo F2 value at one hour ahead was output. We analyzed twenty-two years’ fo F2 data from nine ionosonde stations in the East-Asian sector in this work. The first eleven years’ data were used as a training dataset and the second eleven years’ data were used as a testing dataset. The results show that the performance of Ada Boost-BP is better than those of BP Neural Network(BPNN),Support Vector Regression(SVR) and the IRI model. For example, the Ada Boost-BP prediction absolute error of fo F2 at Irkutsk station(a middle latitude station) is 0.32 MHz, which is better than 0.34 MHz from BPNN, 0.35 MHz from SVR and also significantly outperforms the IRI model whose absolute error is 0.64 MHz. Meanwhile, Ada Boost-BP prediction absolute error at Taipei station from the low latitude is 0.78 MHz, which is better than 0.81 MHz from BPNN, 0.81 MHz from SVR and 1.37 MHz from the IRI model.Finally, the variety characteristics of the Ada Boost-BP prediction error along with seasonal variation, solar activity and latitude variation were also discussed in the paper.

关键词： Ada Boost Ionosphere fo F2 Short-term prediction

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