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Pancheva, D. V.
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Pancheva, D. V.
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- PublicationOpen AccessModelling of the electron density height profiles in the mid-latitude ionospheric D-region(1996-08)
; ; ;Pancheva, D. V.; Geophysical Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria ;Mukhtarov, P. Y.; Geophysical Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria; A new mid-latitude D-region (50-105 km) model of the electron density is presented obtained on the basis of a full wave theory and by a trial-and-error inversion method. Daytime (at different solar zenith angles) absorption measurements by A3-technique made in Bulgaria yielded data with the aid of which the seasonal and diurnal courses of the Ne(h)-profiles were derived. Special attention is drawn to the event diurnal asymmetry, or uneven formation of the ionosphere as a function of insulation. The latter is probably connected with the influence of the diurnal fluctuations in the local temperature on the chemistry involved in the electron loss rate, as well as the diurnal variations of the main ionizing agent (NO) in the D-region. That is why the Ne(h)-profiles in the midlatitude D-region are modelled separately for morning and afternoon hours.134 1812 - PublicationOpen AccessA single-station spectral model of the monthly median F-region critical frequency(1996-08)
; ; ;Pancheva, D. V.; Geophysical Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria ;Mukhtarov, P. Y.; Geophysical Institute, Bulgarian Academy of Sciences, Sofia, Bulgaria; A new single-station monthly median model of the F-region critical frequency has been obtained. A goniometric functional approximation of the monthly median hourly values of f0F2 was accepted. The diurnal course of f0F2 was described by a constant component and four "tides". Only the influence of the annual and semiannual waves in the seasonal course of f0F2 was taken into account. The solar activity was depicted not only by the well known R12 - index, but also by the parameter KR, expressing the linear trend of the monthly mean values of the sunspots for the previous 12 months. The use of this new parameter gives an opportunity for the solar cycle investigated not to be divided into falling and rising parts. The main advantage of the presented monthly median spectral model is that the same approach could be used for the short-term prediction.143 150 - PublicationOpen AccessSolar activity impact on the Earth’s upper atmosphere(2013-12)
; ; ; ; ; ; ; ; ; ; ; ; ; ; ; ;Kutiev, I.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Tsagouri, I.; Institute for Space Applications and Remote Sensing, National Observatory of Athens, 15236 Mount Penteli, Greece ;Perrone, L.; Istituto Nazionale di Geofisica e Vulcanologia, Sezione Roma2, Roma, Italia ;Pancheva, D.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Mukhtarov, P.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Mikhailov, A.; Institute of Terrestrial Magnetism, Ionosphere, and Radio Propagation, Russian Academy of Sciences, 142190 Troitsk, Moskovskaya obl., Russia 5 Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic 6 Institute of Communications and Navigation, German Aerospace Center, 51147 Cologne, Germany 7 Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain 8 Dipartimento di Fisica, Universita` degli Studi di Roma, 00185 Rome, Italy 9 Atmospheric Sounding Station ;Lastovicka, J.; Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic ;Jakowski, N.; Institute of Communications and Navigation, German Aerospace Center, 51147 Cologne, Germany ;Buresova, D.; Institute of Atmospheric Physics ASCR, 14131 Prague, Czech Republic ;Blanch, E.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain ;Andonov, B.; National Institute of Geophysics, Geodesy and Geography, Bulgarian Academy of Sciences, 1113 Sofia, Bulgaria ;Altadill, D.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain ;Magdaleno, S.; Atmospheric Sounding Station ‘‘El Arenosillo’’, INTA, Huelva, Spain ;Parisi, M.; Dipartimento di Fisica, Universita` degli Studi di Roma, 00185 Rome, Italy ;Torta, J. M.; Ebro Observatory, University Ramon Llull, CSIC, E-43520 Roquetes, Spain; ; ; ; ; ; ; ; ; ; ; ; ; ; The paper describes results of the studies devoted to the solar activity impact on the Earth’s upper atmosphere and ionosphere, conducted within the frame of COST ES0803 Action. Aim: The aim of the paper is to represent results coming from different research groups in a unified form, aligning their specific topics into the general context of the subject. Methods: The methods used in the paper are based on data-driven analysis. Specific databases are used for spectrum analysis, empirical modeling, electron density profile reconstruction, and forecasting techniques. Results: Results are grouped in three sections: Medium- and long-term ionospheric response to the changes in solar and geomag- netic activity, storm-time ionospheric response to the solar and geomagnetic forcing, and modeling and forecasting techniques. Section 1 contains five subsections with results on 27-day response of low-latitude ionosphere to solar extreme-ultraviolet (EUV) radiation, response to the recurrent geomagnetic storms, long-term trends in the upper atmosphere, latitudinal dependence of total electron content on EUV changes, and statistical analysis of ionospheric behavior during prolonged period of solar activity. Section 2 contains a study of ionospheric variations induced by recurrent CIR-driven storm, a case-study of polar cap absorption due to an intense CME, and a statistical study of geographic distribution of so-called E-layer dominated ionosphere. Section 3 comprises empirical models for describing and forecasting TEC, the F-layer critical frequency foF2, and the height of maximum plasma density. A study evaluates the usefulness of effective sunspot number in specifying the ionosphere state. An original method is presented, which retrieves the basic thermospheric parameters from ionospheric sounding data.343 657