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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 rain 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 detected 8.5 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 of 7.4±0.8 min. These two coseismic ionospheric disturbances are caused by the acoustic gravity waves excited by partial trans-formation 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： GPS coseismic ionospheric disturbances acoustic gravity waves total electron content earthquake

Empirical modeling of ionospheric F2 layer critical frequency over Wakkanai under geomagnetic quiet and disturbed conditions

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Science China(Technological Sciences) 2012年第5期55卷 1169-1177页

作者： LIU Jing LIU LiBo zhao biqiang WAN WeiXing CHEN YiDing Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing 100029China Graduate University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Space Weather Center for Space Science and Applied ResearchChinese Academy of SciencesBeijing 100190China

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 vari- ability 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 diumal and semidiumal waves, which are modulated by a modified magnetic activity index, the Kf index, reflecting the delayed responses of foF2 to geomagnetic activity forcing. The coeffi- cients 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.

关键词： Empirical modeling Kalman f'dter ionospheric storm

Recent Progresses on Ionospheric Climatology Investigations

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空间科学学报 2012年第5期32卷 665-680页

作者： LIU Libo WAN Weixing CHEN Yiding LE Huijun zhao biqiang (Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029

The ionosphere varies over multiple time scales,which are classified into two categories: the climatology and weather *** this national report,we give a brief summary of recent progresses in ionospheric climatology with focus on(1) the seasonal variations,(2) solar cycle effects, and(3) empirical modeling of the *** seasonal variations of the ionosphere have been explored in many works to give a more detailed picture with regional and global features at various altitudes by analyzing the observation data from various sources and ***,a series of studies reported the response of the ionosphere to solar cycle variations,which revealed some novel and detailed features of solar activity dependence of ionospheric parameters at different altitudes. These investigations have improved our understanding on the states of the ionosphere and underlying fundamental processes,provided clues to future studies on ionospheric weather,and guided ionospheric modeling,forecasting and related applications.

关键词： Ionosphere Climatological variation Seasonal variations Solar cycle Ionospheric modeling

Suppression of modulation-induced polarization error in spliceless open-loop fiber optic gyroscope [Invited]

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Chinese Optics Letters 2024年第7期22卷 6-11页

作者： Lin Chen Peitong He biqiang Jiang Jianlin zhao Key Laboratory of Light Field Manipulation and Information Acquisition and Shaanxi Key Laboratory of Optical Information TechnologySchool of Physical Science and TechnologyNorthwestern Polytechnical UniversityXi’an 710129China Zhejiang Lab Hangzhou 311100China

The suppression of polarization cross talk in lead zirconate titanate phase modulators as a key error source has been challenging for open-loop fiber optic gyroscopes(FOGs).We developed a polarization-diversity optical frequency domain reflectometry(OFDR)to measure the distributed modulation polarization error in the *** error contributes 8×10^(−6) rad to FOG’s bias *** a UV-fabricated in-fiberλ/4 wave plate and polarization-mode converter with fiber taper technology,the modulation error has been suppressed by 15 dB in assembled *** approach reduced error with temperature from 25°/h to 0.7°/h,meeting the requirements of control-level gyroscopes with bias errors less than 1°/h.

关键词： fiber optic gyroscope inline wave plate optical frequency domain reflectometry polarization-mode converter.

Ionospheric and geomagnetic disturbances caused by the 2008 Wenchuan earthquake:A revisit

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Ionospheric and geomagnetic disturbances caused by the 2008 ...

High-speed Stream Impacts on the Equatorial Ionization Anomaly Region during the Deep Solar Minimum Year 2008

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： biqiang zhao Yongqiang Hao Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences Department of Geophysics Peking University

Previous works have shown that coseismic ionospheric disturbances(CIDs) after the tsunamigenic2011 Tohoku earthquake(Tohoku EQ,M9.1) covered a vast area and were observed thousands of kilometers away from the *** the purpose of making a comprehensive comparison between powerful oceanic and inland EQs,we conduct a retrospective investigation of CIDs and geomagnetic responses to the 2008 Wenchuan EQ(M7.9) using a combination of techniques,total electron content,HF Doppler,and ground *** is the very first study to present CIDs recorded by different techniques at co-located sites and profiled with regard to changes of both ionospheric plasma and current(geomagnetic field) *** integrated observation also shows that(1) in the Wenchuan case,most of the ionospheric and geomagnetic disturbances were observed within 1000 km distance which is far less than the Tohoku case;(2) two groups of CIDs were found with maximum amplitudes in the direction of azimuth 150° and 135°,respectively;and(3) the geomagnetic changes were only registered by three magnetometers located to the east and southeast of the *** the facts indicate that the main directional lobe of Wenchuan EQ energy propagation is to southeast and perpendicular to the direction of the fault rupture,but this kind of directivity is not that distinct in the Tohoku *** suggest that the different fault slip(inland or submarine) affecting the way of couplings of lithosphere with atmosphere may contribute to the discrepancies between the two events.

关键词： Ionospheric and geomagnetic changes caused by a major inland earthquake Strong directivity of CID distribution related to fault rupture direction Different features in CIDs of inland case compared with oceanic case

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High-speed Stream Impacts on the Equatorial Ionization Anoma...

Preliminary experimental results by the prototype of Sanya Incoherent Scatter Radar

中国空间科学学会空间物理学专业委员会第十五届全国日地空间物理学研讨会

作者：刘晶 Libo Liu biqiang zhao 中国科学院地质与地球物理研究所

To demonstrate high-speed stream effects during the recent deep solar minimum year 2008,we have analyzed manually scaled foF2 and hmF2 at Jicamarca and total electron content(TEC)in the equatorial ionization anomaly(EIA)region over the America longitudinal *** results reveal that a prominent 9-day oscillation appears in the hmF2 and foF2 at the dip *** 9-day oscillation amplitudes of foF2 are not always positively correlated with TEC in the equatorial ionosphere and they show non-linear dependence on the intensity of geomagnetic *** the outputs of Fejer and Scherliess’s[1997]empirical model,we found that this periodicity is also present in equatorial vertical drifts caused by disturbance dynamo electric field(DDEF)but absent in the drifts due to prompt penetration electric field(PPEF).DDEF effects on the equatorial periodic variations alone are not sufficient to explain the observed phenomena;other mechanisms,such as thermal expansion/contraction and neutral composition changes,are also the plausible causes of the periodic oscillation in the equatorial ***,the complicated patterns appear in the 9-day band-pass-filtered TEC perturbations in the EIA region,and they are quite different from the patterns of global coherent thermospheric oscillations triggered by high-speed *** also found that the latitudinal variations of band-passed-filtered TEC present different behaviors involving tilt latitudinal configuration,anti-phased correlation between the crests and trough,and south-north asymmetry,which vary as a function of season,local time,or even from event to event.

关键词：

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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 *** 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 *** this work,we have summarized the preliminary experimental results based on the *** amplitude and phase among 256 channels were first calibrated through an embedded internal monitoring *** mean oscillation of the amplitude and phase after calibration were about 1 dB and 5°,respectively,which met the basic *** beam directivity was confirmed by crossing screen of the International Space *** SYISR-8 was further used to detect the tropospheric wind profile and *** derived winds were evaluated by comparison with independent radiosonde and balloon-based GPS *** SYISR-8 was able to observe several typical meteor echoes,such as the meteor head echo,range-spread trail echo,and specular trail *** 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

Recent progress in ionospheric earthquake precursor study in China:A brief review

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Recent progress in ionospheric earthquake precursor study in...

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

中国科学院地质与地球物理研究所2015年度（第15届）学术年会

作者： Huijun Le Jing Liu biqiang zhao Libo Liu Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences Institute of Earthquake Science China Earthquake Administration

The study of ionospheric anomaly variation before large earthquakes has attracted the attention of geophysicists for many *** is primarily because ionospheric anomaly variation has been considered to constitute one possible method to identify earthquake *** China covers several major earthquake zones,it is critical for Chinese scientists to study possible ionospheric earthquake *** this report,we provide a brief summary of recent progress in the study of ionospheric earthquake precursors mainly from Chinese mainland researchers,as well as some other *** report focuses on:(1) some case studies of ionospheric abnormal behaviors before some great earthquakes around the world(e.g.,M7.9 Wenchuan Earthquake,M9.0 Tohoku-Oki Earthquake,M7.0 Haiti Earthquake);and(2)some statistical characteristics of ionospheric anomalies before earthquakes,including their temporal and spatial distributions,and the relationship with the forthcoming *** above-mentioned studies may provide some new and beneficial insights for the future study of ionospheric earthquake precursors.

关键词： Ionosphere Total electron content Statistical analysis Seismo-ionospheric anomaly

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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