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Recent ionospheric investigations in China(2018–2019)

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Earth and Planetary Physics 2020年第3期4卷 179-205页

作者： libo liu WeiXing Wan 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 100101China College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100019China

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 *** 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.

关键词： ionosphere ionospheric storm ionospheric climatology ionospheric irregularity GNSS space weather

Ionospheric Investigations Conducted by Chinese Mainland Scientists in 2020-2021

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空间科学学报 2022年第4期42卷 653-683页

作者： liu libo LEI Jiuhou liu Jing Key Laboratory of Earth and Planetary Physics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029 Heilongjiang Mohe National Observatory of Geophysics Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029 College of Earth and Planetary Sciences University of the Chinese Academy of SciencesBeijing 100049 Chinese Academy of Sciences Key Laboratory of Geospace Environment School of Earth and Space SciencesUniversity of Science and Technology of ChinaHefei 230022 School of Space Science and Physics Shandong Key Laboratory of Optical Astronomy and Solar-Terrestrial EnvironmentInstitute of Space SciencesShandong UniversityWeihai 264209

In this report,we outline works done by scientists from the Mainland of China on various ionospheric topics after the release of the National Report of China in 2020 on ionospheric researchto the Committee on Space Research(COSPAR).More than 170 papers were published in *** 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 ionosphere and sounding *** ionospheres are included for the first time.

关键词： Ionospheric Space weather Planetary ionospheres

Nighttime electron density enhancements at middle and low latitudes in East Asia

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Science China Earth Sciences 2015年第4期58卷 551-561页

作者： ZHANG YanYan liu libo CHEN YiDing liu Jing YU You LI Ming Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences University of Chinese Academy of Sciences

Nighttime enhancements in ionospheric electron density at mid- and low-latitudes are investigated by using the critical frequency of the F2-1ayer （foF2） data measured from ionosonde stations at Okinawa （26.3°N, 127.8°E, Geomagnetic 15.3°N）, Yamagawa （31.2°N, 130.6°E, Geomagnetic 20.4°N）, Kokubunji （35.7°N, 139.5°E, Geomagnetic 25.5°N）, and Wakkanai （45.4°N, 141.7°E, Geomagnetic 35.4°N） in East Asia during several solar cycles. The results show that there are obvious seasonal and solar activity dependencies of the nighttime electron density enhancements. The enhancements are termed pre-midnight enhancement and post-midnight enhancement, according to the local time when the enhancement appeared. The former has a higher occurrence probability in summer months than in winter months. In contrast, the latter has a larger occurrence probability in winter months than in summer months. Moreover, the nighttime enhancements in electron density are more likely to occur at lower solar activity. These seasonal and solar activity variations of the nighttime enhancements in electron density can be explained in terms of the combined effects of downward plasma flux from the plasmasphere and the neutral winds.

关键词： nighttime electron density enhancements critical frequency of the F2-1ayer seasonal and solar activity dependencies vertical equivalent winds

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

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

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

Solar activity effects of the ionosphere: A brief review

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Chinese Science Bulletin 2011年第12期56卷 1202-1211页

作者： liu libo WAN WeiXing CHEN YiDing LE HuiJun Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China State Key Laboratory of Space Weather Center for Space Science andApplied Research Chinese Academy of Sciences Beijing 100190 China

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.

关键词：太阳活动周期电离层物理电离层模型太阳能太阳辐射时间尺度辐射观测物理过程

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 iono- spheric 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 FAls 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 kin, 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 kin, lower than h＇Es and the difference is mostly 10-20 km. December solstice seemed to be the minimum period of occurrence when the FA! ech- oes were commonly detected at a narrow altitude range 90-100 km. Moreover, simultaneous radar and GPS observations dur- ing 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： low-latitude ionosphere ionospheric irregularities VHF radar

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