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Differential areas for differential stations (DADS): A new method of establishing grid ionospheric model

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Chinese Science Bulletin 2002年第12期47卷 1033-1036页

作者： Yuan, YB Ou, JK Chinese Acad Sci Inst Geodesy & Geophys Lab Dynam Geodesy Wuhan 430077 Peoples R China

Differential Area for Differential Stations (DADS), a new method of establishing grid ionospheric model, is presented. The preliminary results show that it is possible to establish a real time large range high precision grid ionospheric model (GIM) using the DADS and the GPS data of the Chinese crust movement observation network (CCMON).

关键词： GPS grid ionospheric model crust movement observa-tion network DADS.

Anomaly distribution of ionospheric total electron content responses to some solar flares

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Earth and Planetary Physics 2019年第6期3卷 481-488页

作者： HuiJun Le LiBo Liu YiDing Chen Hui Zhang Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China Innovation Academy of 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

Previous studies have shown that the ionospheric responses to a solar flare are significantly dependent on the solar zenith angle(SZA):the ionospheric responses are negatively related to the *** largest enhancement in electron density always occurs around the subsolar ***,from 2001 to 2014,the global distribution of total electron content(TEC)responses showed no obvious relationship between the increases in TEC and the SZA during some solar *** these solar flares,the greatest enhancements in TEC did not appear around the subsolar point,but rather far away from the subsolar *** distribution of TEC enhancements showed larger TEC enhancements along the same *** distribution of anomalous ionospheric responses to the solar flares was not structured the same as traveling ionospheric *** anomaly distribution was also unrelated to the distribution of background neutral *** could not be explained by changes in the photochemical process induced by the solar ***,the transport process could be one of the main reasons for the anomaly distribution of ionospheric responses to the solar *** anomaly distribution also suggests that not only the photochemical process but also the transport process could significantly affect the variation in ionospheric electron density during some solar flares.

关键词： solar flare ionospheric response transport process

PROGRESSES IN ionospheric RESEARCH, 2000-2002: A BRIEF REVIEW

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空间科学学报 2002年第z1期22卷 99-110页

作者： WAN Weixing LIU Libo Wuhan Institute of Physics and Mathematics The Chinese Academy of Sciences Wuhan 430071 P.R.China Wuhan Institute of Physics and MathematicsThe Chinese Academy of Sciences Wuhan 430071 P.R.China

This brief report reviews the recent developments in ionospheric physics studies made by Chinese scientists. It covers areas from the numerical simulations and theoretical researches on ionospheric properties, ionosph... 详细信息

关键词： Ionosphere, ionospheric storm, ionospheric model, ionospheric property

Characteristics of ionospheric scintillation climatology over Indian low-latitude region during the 24th solar maximum period

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Geodesy and Geodynamics 2019年第2期10卷 110-117页

作者： K.Sahithi M.Sridhar Sarat K.Kotamraju K.Ch.Sri Kavya G.Sivavaraprasad D.Venkata Ratnam Ch.Deepthi Department of Electronics and Communication Engineering Koneru Lakshamaiah Education Foundation

The amplitude and phase of L-band satellite signals are fluctuated randomly due to small scale electron density irregularity structures in the ionosphere which result in fleeting variations, known as 'ionospheric scintillations'. The Global Navigation Satellite System(GNSS) is a profound remote sensing tool to monitor, model and forecast the ionospheric weather conditions. In this paper, the GNSS amplitude scintillation data has been analyzed during the year 2013 at Bengaluru(12.9°N, 77.59°E) and Lucknow(26.8467°N, 80.9462°E) stations to reinforce climatology of ionospheric scintillation over Indian low-latitude region. The probability of scintillation occurrence and their variations over equatorial and Equatorial Ionization Anomaly(EIA) regions in India are analyzed during various geomagnetic quiet and disturbed days, months and seasons. The annual occurrence of amplitude scintillations are mapped with the function of local time. It is observed from the experimental results that the probability of scintillations occurrences is higher over EIA region than over the equatorial region. The probability of scintillations is higher during March equinox and December solstice, and lowest during June *** of scintillations is intense during post-sunset period. The maximum percentage of scintillation occurrences at the two stations are recorded in November. Moreover, the highest percentage of scintillation occurrences took place on storm day(March 17, 2013) at the two stations. This work would be helpful for understanding the features of GNSS amplitude scintillations over Southern and Northern Indian regions. Moreover, these kinds of investigations are helpful for developing new algorithms to nowcast and forecast ionospheric scintillations over Indian Sub-continent.

关键词： GNSS ionospheric scintillations Indian low-latitude region

Chinese ionospheric investigations in 2016–2017

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Earth and Planetary Physics 2018年第2期2卷 89-111页

作者： LiBo Liu 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 College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049China

After the release of the previous report to the Committee on Space Research(COSPAR) on progress achieved by Chinese scientists in ionospheric researches(Liu LB and Wan WX, 2016), in the recent two years(2016–2017) many interesting new investigations into various ionospheric related issues have been completed. In this report, about 100 publications are summarized. The topics highlighted are as follows: ionospheric space weather, ionospheric dynamics, ionospheric climatology and modelling, ionospheric irregularity and scintillation, Global Navigation Satellite System(GNSS) related ionospheric issues and other techniques, and radio wave propagation in the ionosphere. An outstanding feature is that more and more observations from the Meridional Project supported the ionospheric investigations.

关键词： ionosphere ionospheric storm space weather ionospheric dynamics irregularity

A brief review of equatorial ionization anomaly and ionospheric irregularities

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Earth and Planetary Physics 2018年第4期2卷 257-275页

作者： Nanan Balan LiBo Liu HuiJun Le 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 the Chinese Academy of Sciences

Following a brief history and progress of ionospheric research, this paper presents a brief review of the recent developments in the understanding of two major phenomena in low and mid latitude ionosphere—the equatorial ionization anomaly(EIA) and involved equatorial plasma fountain(EPF) and ionospheric irregularities. Unlike the easy-to-understand misinterpretations, the EPF involves field perpendicular E×B plasma drift and field-aligned plasma diffusion acting together and plasma flowing in the direction of the resultant at all points along the field lines at all altitudes. The EIA is formed mainly from the removal of plasma from around the equator by the upward E×B drift creating the trough and consequently the crests with small accumulation of plasma at the crests when the crests are within ~±20° magnetic latitudes and no accumulation when they are beyond ~±25° magnetic latitudes. The strong EIA under magnetically active conditions arises from the simultaneous impulsive action of eastward prompt penetration electric field and equatorward neutral wind. Intense ionospheric irregularities develop in the post-sunset bottom-side equatorial ionosphere when it rises to high altitudes, and evolve nonlinearly into the topside. Pre-reversal enhancement(PRE) of the vertical upward E×B drift and its fluctuations amplified during PRE provide the driving force and seed, with neutral wind and gravity waves being the primary sources. At low solar activity especially in summer when fast varying PRE is absent, the slow varying gravity waves including large scale waves(LSW)seem to act as both driver and seed for weak irregularities. At mid latitudes, the irregularities are weak and associated with medium scale traveling ionospheric disturbances(MSTIDs). A low latitude minimum in the occurrence of the irregularities at March equinox predicted by theoretical models is identified. The minimum occurs on the poleward side of the EIA crest and shifts equatorward from ~25° magnetic latit

关键词： equatorial ionization anomaly ionospheric irregularities

Atmospheric Meteorological Parameters and ionospheric F2 Layer Critical Frequency (foF2) Observation for 6^th December, 2016 Indonesia Earthquake (M 6.5): A Case Study

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Journal of Atmospheric Science Research 2018年第1期1卷 6-12页

作者： Suman Paul Department of Physics Rishi Bankim Chandra Evening CollegeNaihati24 Parganas (N)743165India Centre of Advanced Study in Radio Physics and Electronics University of CalcuttaKolkata700009India

On 6^th December, 2016, an earthquake with M 6.5 occurred at the tectonic plate boundary, southwest of Sumatra, Indonesia (Latitude: 0.5897°S, Longitude: 101.3431°E). In this case, ionospheric critical frequency of F2 layer (foF2) variations and meteorological parameters, viz., air temperature, relative humidity, atmospheric pressure and wind speed variations were investigated so as to detect any anomalies. Data are obtained from different websites freely available for researchers. In the absence of real ionosonde foF2 data, IRI 2016 model data were used. For each parameter, anomaly window were defined when values fell beyond ± 6 ℃,ionospheric foF2 observations might help us to predict an earthquake about a week prior to the occurrence.

关键词： ionospheric ionospheric foF2 anomaly Meteorological parameter anomaly Short-term prediction

On the Tempo-Spatial Evolution of the Lower ionospheric Perturbation for the 2016 Kumamoto Earthquakes from Comparisons of VLF Propagation Data Observed at Multiple Stations with Wave-Hop Theoretical Computations

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Open Journal of Earthquake Research 2018年第3期7卷 161-185页

作者： Tomokazu Asano Masashi Hayakawa Hayakawa Institute of Seismo Electromagnetics Co. Ltd. (Hi-SEM) University of Electro-Communications (UEC) Alliance Center 1-1-1 Kojima-cho Chofu Japan Advanced Wireless & Communications Research Center UEC Chofu Japan

There have been published many papers on VLF (very low frequency) characteristics to study seismo-ionospheric perturbations. Usually VLF records (amplitude and/or phase) are used to investigate mainly the temporal evolution of VLF propagation anomalies with special attention to one particular propagation path. The most important advantage of this paper is the simultaneous use of several propagation paths. A succession of earthquakes (EQs) happened in the Kumamoto area in Kyusyu Island;two strong foreshocks with magnitude of 6.5 and 6.4 on 14 April (UT) and the main shock with magnitude 7.3 on 15 April (UT). Because the EQ epicenters are not far from the VLF transmitter (with the call sign of JJI in Miyazaki prefecture), we can utilize simultaneously 8 observing stations of our network all over Japan. Together with the use of theoretical computations based on wave-hop theory, we try to trace both the temporal and spatial evolutions of the ionospheric perturbation associated with this succession of EQs. It is found that the ionospheric perturbation begins to appear about two weeks before the EQs, and this perturbation becomes most developed 5 - 3 days before the main shock. When the perturbation is most disturbed, the maximum change in vertical direction is depletion in the VLF effective ionospheric height of the order of 10 km, and its horizontal scale (or its radius) is about 1000 km. These spatio-temporal changes of the seismo-ionospheric perturbation will be investigated in details in the discus-sion, a comparison has made with the VLF characteristics of the 1995 Kobe with the same magnitude and of the same fault-type, and a brief discussion on the generation mechanism of seismo-ionospheric perturbation is finally made.

关键词： VLF/LF Propagation Anomaly ionospheric Perturbations Earthquake Precursor Earthquake Prediction the 2016 Kumamoto Earthquakes Japanese VLF/LF Network Wave-Hop Computation Nighttime Fluctuation Method Atmospheric Oscillation Hypothesis

Study of the ionospheric Effects of Selected Cases of Solar Flares over Abidjan

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Journal of Physical Science and Application 2018年第3期8卷 18-25页

作者： Jean Baptiste Ackah Olivier Kouadio Obrou Sylvain Malan Ahoua Laboratoire de Physique de l'Atmosphere Universite Felix Houphouet Boigny Abidjan22 B.P.582 Abidjan 22Cote-d'Ivoire

The present study investigates the changes in TEC(total electron content)and ionospheric scintillation index(S4)inferred from the GNSS data recorded at the SCINDA station of Abidjan(Latitude=5.34°N,Longitude=3.90°W)during and after a solar *** the course of 2014,a year of high solar activity,three(3)cases of extreme(X1.66)and moderate(M6.23 and M2.13)solar flares recorded in the months of September and December effects on the ionosphere have been studied using the X ray fluxes,the magnetic parameters(Vx,Bz,Dst),the ionospheric scintillation index S4 and TEC and its ROT(time rate of change).The ROT exhibits a prominent peak between ten(10)and twelve(12)minutes after the occurrence of the maximum peak of the time rate of change of the X-ray flux emitted during the *** ROT maximum value occurs simultaneously with an enhancement of the S4 *** perturbations of the solar flare on the TEC in the SCINDA station of Abidjan occur within 42 to 54 hours after an M-class solar flare and within 46 to 58 hours following an X-Class solar *** magnetic storms resulted from these flares show an increment of 20%on VTEC observed when compared to the average VTEC()computed from the most five(5)quietest days of the selected months.

关键词： TEC ionospheric scintillation solar flare X-ray