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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

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

A comparison of mesospheric winds measured by FPI and meteor radar located at 40N

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Science China(Technological Sciences) 2012年第5期55卷 1245-1250页

作者： JIANG GuoYing XU JiYao YUAN Wei ning baiqi WAN WeiXing HU LianHuan State Key Laboratory of Space Weather Center for Space Science and Applied ResearchChinese Academy of SciencesBeijing 100190China Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of Sciences Beijing 100029China

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 rneridional 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.

关键词： FPI meteor radar mesospheric wind

TIME-IGGCAS model validation:Comparisons with empirical models and observations

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Science China(Technological Sciences) 2008年第3期51卷 308-322页

作者： YUE XinAn WAN WeiXing LIU LiBo ning baiqi ZHAO BiQiang ZHANG ManLian Institute of Geology and Geophysics Chinese Academy of SciencesBeijing 100029China Wuhan Institute of Physics and Mathematics Chinese Academy of SciencesWuhan 430071China Graduate University Chinese Academy of SciencesBeijing 100049China

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.

关键词： ionosphere theoretical model empirical model satellite observation relative deviation

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

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： ionospheric modeling total electron content empirical orthogonal functions

The possibility of using all-sky meteor radar to observe ionospheric E-region field-aligned irregularities

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Science China(Technological Sciences) 2019年第8期62卷 1431-1437页

作者： XIE HaiYong LI GuoZhu ning baiqi REID Iain HU LianHuan WU BaoYuan YU You YANG SiPeng Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China Beijing National Observatory' of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China College of Earth and Planetary Sciences University of Chinese Academy of Science Beijing 100029 China ATmospheric RAD ar (ATRAD) Pty Ltd Thebarton 5031 Australia School of Physical Sciences University of Adelaide Adelaide 5005 Australia

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.

关键词： meteor radar ionospheric irregularities sporadic E layer

Seasonal variations of night mesopause temperature in Beijing observed by SATI4

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Science China(Technological Sciences) 2012年第5期55卷 1295-1301页

作者： XIONG JianGang WAN WeiXing ning baiqi LIU LiBo WU BaoYuan HU LianHuan XU Tao Beijing National Observatory of Space Environment Institute of Geology and GeophysicsChinese Academy of SciencesBeijing 100029China

The data observed by a spectral airglow temperature imager （SATI） at Beijing National Observatory of Space Environment from July 23, 2008 to July 3l, 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 02 （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 Ion is 201.2 K, higher than average temperature 194.8 K at 94 kin. 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 oscillation. 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.

关键词： mesopause temperature airglow seasonal variations SATI

Onset location of scintillation-producing spread-F plume over Sanya

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Science China Earth Sciences 2016年第8期59卷 1692-1699页

作者： ZHENG JianChang HUANG ZhaoGuo WU Zhi HAO XiQing JI JiaLun ning baiqi HU LianHuan ZHAO XiuKuan LI GuoZhu Key Laboratory of Earth and Planetary Physics Institute of Geology and Geophysics Chinese Academy of Sciences Beijing National Observatory of Space Environment Institute of Geology and Geophysics Chinese Academy of Sciences

Equatorial spread-F (ESF) backscatter plumes are often observed in radar range-time-intensity (RTI) maps at low latitude. Except case studies, few statistical investigations on the onset locations of scintillation-producing ESF plumes at given sites have been conducted. In this study, a statistical analysis is carried out on onset locations of ESF backscatter plumes observed at a low-latitude location Sanya (18.4°N, 109.6°E; dip lat 12.8°N) during equinoctial months of 2013. By employing a tracing method to locate backscatter plumes, we estimate the onset longitudes of periodic plumes obtained from the Sanya VHF radar five-beam steering measurements. The results show that the inter-plume distances (in longitude) are mostly confined within 200–600 km, and the ESF plumes producing ionospheric scintillations over Sanya are almost exclusively generated at the longitudes of 94°–110°E. The results indicate the necessity to monitor ESF plume initial generation in the longitude region of 94°–110°E to better understand the day-to-day variability in the occurrence of ionospheric scintillations over Sanya.

关键词： Equatorial spread-F Backscatter plume Onset location VHF radar Zonal drift