Adriena Ondrášková

Adriena Ondrášková
Comenius University Bratislava · Department of Astronomy, Physics of the Earth and Meteorology

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24
Publications
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Publications

Publications (24)
Article
The precise determination of instantaneous frequency of Schumann resonance (SR) modes, with the possibility of application to relatively short signal sequences, seems to be important for detailed analysis of SR modal frequency variations. Contrary to commonly used method of obtaining modal frequencies by the Lorentz function fitting of DFT spectra,...
Article
Full-text available
The more precise determination of instantaneous peak frequency of Schumann resonance (SR) modes, especially based on relatively short signal sequences, seems to be important for detailed analysis of SR modal frequencies variations. Contrary to commonly used method of obtaining modal frequencies by Lorentzian fitting of DFT spectra, the attempt was...
Article
For the period 1988–2002, it has been shown that the SR mode frequencies and Q-factors decrease with the decrease of X-ray radiation toward the solar cycle minimum (Sátori et al., 2005). In the present study, a decrease of frequencies and Q-factors of all first four SR modes from the latest solar cycle maximum to the anomalous minimum of 2008–2009...
Article
Altitude—temporal cross-sections q(z, t) of atmospheric ionization rates by solar protons above the polar regions were calculated using the GOES-10 satellite data on solar proton fluxes for the period of solar proton flare (SPF) on July 14, 2000. The values of q(z, t) were used further in calculations of variations of the atmospheric chemical compo...
Article
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Under favourable conditions sprites appear above large storms. Long continuing current in tens of ms in the parent +CG stroke radiates electromagnetic energy also in the Schumann resonance (SR) band. Optical and Extremely Low Frequency (ELF) observations at the Astronomical and Geophysical Observatory (AGO) near Modra are analyzed to find these two...
Article
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A significant decrease of the fundamental Schumann resonance frequency during the solar cycle minimum of 2008-9 as observed at Modra Observatory The Schumann resonances (SR) are electromagnetic eigenmodes of the resonator bounded by the Earth's surface and the lower ionosphere. The SR frequency variability has been studied for more than 4 decades....
Article
Superimposed on the continuous Schumann resonance (SR) background in the extremely low frequency (ELF) band, transient signals (e.g. bursts) can be observed, which originate from intense lightning discharges occurring at different locations on the globe. From the many transients that were observed at the Astronomical and Geophysical Observatory (AG...
Article
Response of the middle atmosphere and especially of electron and ion concentrations in the lower ionosphere to one of the strongest Solar Proton Events (SPE) of the 23rd solar cycle on July 14, 2000 is studied with the emphasis on the differences in ionosphere over the North and the South Pole. General circulation model (GCM) and 3D chemical global...
Article
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The electromagnetic eigenmodes of Earth-ionosphere global resonator known as Schumann Resonances (SR) are excited by global lightning activity. The simultaneous measurements of electric field in the ELF (~5 – 100 Hz) frequency band at two observatories clearly reveal the global character of the resonator response to the excitation both in the perma...
Article
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The paper presents a summary of more than 4 years of continuous Schumann resonance (SR) monitoring of the vertical electric component at Modra Observatory. Principal parameters (peak frequency, amplitude, and quality factor) are determined for four resonances from 7 to 30 Hz, i.e., for modes one through four. Attention is also given to the less fre...
Article
Simulations of the response of the neutral and ionized composition in the middle atmosphere D-region for ions to the July 14 2000 solar proton event SPE are used to find its spatial and temporal structure near both polar regions It was important for such study to take into account a natural difference between Northern pole day conditions and Southe...
Article
The Schumann resonances - electromagnetic eigenmodes of the resonator bounded by the Earth's surface and lower ionosphere, permanently excited by the global lightning activity - are now widely monitored experimentally. To relate the obtained data with ionospheric parameters the computer modeling of such a resonator is necessary. The various approac...
Article
Fluxes of energetic solar protons penetrate deep into the Earth’s polar cap middle atmosphere. Interacting with molecules of the air they cause additional dissociation and ionization, and the formed NOx, OHy and ions enter chemical and ion-molecular reactions. Induced changes of the ionospheric D-layer are modeled by a 1D model of lower ionosphere...
Article
This paper is a first-stage study of the effect the solar cosmic rays cause in the polar lower ionosphere though some aspects of the effect on polar atmosphere have been already studied by other authors. Numerical simulations have been made to find the response of both neutral and ionised species in the middle atmosphere to the strong solar proton...
Article
At the Astronomical and Geophysical Observatory of FMFI UK at Modra, the permanent monitoring of Schumann resonance (SchR) spectra has been performed for more than three years (in electric field component - the SchR magnetic field component spectra have been measured - up to now - only intermittently for a shorter time). During second half of Octob...
Article
Fluxes of energetic solar protons penetrate deep into the Earth's polar cap middle atmosphere. Interacting with molecules of air they cause dissociative ionization and start chains of chemical and ion-molecular reactions. Induced changes of the ionospheric D-layer are modelled by a 1-D model of lower ionosphere with chemistry using neutral species...
Article
One of the strongest solar proton events (SPE) occurred in October 1989. The ionized layer in the atmosphere is a result of interaction between radiation (electromagnetic and particle) and the neutral atmosphere. Changes of the neutral and ionized composition due to this event are examined. The ionization rate, and ozone, NO and OH density temporal...
Article
Photochemical simulations /1,2/ reveal strong disturbances of ionization rates, electron density and chemical composition after solar proton events (SPEs). For example, SPE occurred in October 1989 caused strong increase of electron density (several orders) and destruction of ozone content. Ozone was practically destroyed after this event in the me...
Article
The response of neutral species and electron density to October 1989 SPE is simulated. Solar proton fluxes measured aboard the Russian polar satellite system "Meteor" are used to calculate ionization rates. The ionization rate, and ozone, NO, OH and other species density temporal and vertical disturbances induced by the SPE, calculated by a 1-D tim...
Article
One of the strongest solar proton events (SPE) occurred in October 1989. Its forcing of the middle atmosphere chemistry including ionized components in the D-region is examined. The ionization rate, and ozone, NO and OH density temporal and spatial (vertical) deviations induced by the SPE, calculated by a 1-D time-dependent photochemical model sepa...
Article
Full-text available
The seasonal variation of the 162 kHz radio wave reflection height was measured indirectly at Panská Ves using the IPHA method described in Fišer and Matys (1992). The fact that these waves are reflected at the height where the electron concentration is about 3.5 × 108m-3was used to model this height using a 1-D model of the lower ionosphere electr...
Article
Calculations are carried out of upward propagation of a tropospherically forced 10-day planetary wave into the upper middle atmosphere with the use of the COMMA-R model of the University of Cologne, of its transformation into a wave in electron density by means of the model of the Comenius University, and of its final transformation into a wave in...
Article
A one-dimensional numerical model has been developed which gives the vertical profiles of the electron and ion concentrations at altitudes between 50 and 100 km. The model has been constructed for day-time ionization conditions in midlatitudes and yields a slightly abbreviated scheme of ion-molecular reactions. Neutral species concentrations have b...

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