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Ding Z.,China Research Institute of Radiowave Propagation | Ding Z.,Chinese Academy of Sciences | Xu Z.,National Key Laboratory of Electro Magnetic Environment
2012 10th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2012 | Year: 2012

The difference of the month median value at two typical equilatitudinal mid-latitude stations Urumchi (43.8°N, 87.6°E) and Changchun (43.83°N, 125.2°E), China are used to study the ionpsheric long-term trend. The main results are: (1) there is no obvious long-term trend for ΔfoE. This point is different from Jarvis (2008), who use the data from the station near the boundary between the ocean and continent. (2) there are positive (increasing) trend in daytime and little negative trend in night for ΔfoF2, which is maybe related to the difference of meridional wind. There are notable seasonal variations: the negative trend with minimum in summer, positive trend with maximum in equinox. (3) The ΔhmF2 show negative trend in all month and local time. There is a minimum at noon in June and larger value in other seasons. The trend of ΔhmF2 is maybe related to the spatial variability in the trend of thermosphere. © 2012 IEEE. Source


Li N.,China Research Institute of Radio Wave Propagation | Li N.,National Key Laboratory of Electro Magnetic Environment | Ding Z.,China Research Institute of Radio Wave Propagation | Ding Z.,Chinese Academy of Sciences | And 5 more authors.
2012 10th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2012 | Year: 2012

We presented in this paper the ionosphere variation characteristics during solar flares with location, season and solar activity level at Kunming site (25.6°N, 103.8°E), using the data measured by MF radar and ionosonde. Results showed: (1) the maximum amplitudes both D region and fmin during solar flares appeared near at noon; there was no the strict corresponding relationship during solar flares between F layer critical frequency (foF2) and location time. (2) seasonal variation of increasing amplitude of electron density in D layer during solar flares reached the maximum in summer; that of fmin was maximal in autumn, second in spring; that of foF2 reached the maximum in winter, second in autumn and least in spring. (3) the variation of ionosphere showed the positive correlation with the level of solar flare. (4) the ionosphere of D region had different characteristics with F layer ionosphere during solar flare on November 4, 2008. © 2012 IEEE. Source


Li N.,China Research Institute of Radio Wave Propagation | Li N.,National Key Laboratory of Electro Magnetic Environment | Ding Z.,China Research Institute of Radio Wave Propagation | Ding Z.,Chinese Academy of Sciences | And 3 more authors.
2012 10th International Symposium on Antennas, Propagation and EM Theory, ISAPE 2012 | Year: 2012

We investigated disturbance propagation characteristics of ionosphere at three stations near 120° meridian chain using data by Vertical sounder during geomagnetic storms form April 12, 1981 to April 16, 1981. The result showed that there have significant perturbation of foF2 and h'F in the ionosphere at three stations during Magnetic storm, at the same time seven traveling ionospheric disturbance (TID) events occurred from higher latitude to lower latitude. Most events of TID happened at night, and the phase velocity increase gradually directing to low latitude. © 2012 IEEE. Source

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