Complex analysis of the middle-latitude ionosphere parameters during the geomagnetic storm at Jan, 20, 2010 based on the DEMETER satellite data analysed using DIAS Software

In the Institute of Space Techniques and Technologies of the National Center of Space Research and Technology (Almaty, Republic of Kazakhstan) the DIAS (Detection of Ionosphere Anomalies Software) was developed and used for scientific research. The software was designed for ionosphere anomalies detection, identifying and analyzing from satellite spectral and wave data from scientific payload installed on the DEMETER spacecraft. The main task of DIAS Software is to provide the researcher with a convenient tool for detection and identifying of the sources of electromagnetic radiation, disturbances of the ionic and electronic component of the ionosphere, and other ionosphere parameters from satellite data. Using this Software, a complex research of the state of the medium-latitude ionosphere during a geomagnetic storm on January 10, 2010 was done. Processing and analysis of the electric and magnetic components of the field in ULF, ELF and VLF band is carried out; as well as temperature, velocity and density of ionic and electronic plasma components and fluxes of energetic electrons at satel lite altitude during a storm.

Comparative Study of the Energetic Electrons Registered Together with the Broad Band Emissions in Different Regions of the Ionosphere

ELF/VLF waves have been registered in the outer polar cusps simultaneously with high energy electrons fluxes by the satellites Magion 4 (subsatellite to Interball 1), Polar and CLUSTER. Further, we discuss similar observations in the different regions of the ionosphere, where DEMETER registered energetic electrons. The DEMETER satellite operating on the nearly polar orbit at the altitude 650 km crossed different regions in the ionosphere. Registrations of ELF/VLF/HF waves together with the energetic electrons in the polar cusp, in the ionospheric trough and over thunderstorm areas are presented in this paper. The three satellites of ESA’s Swarm mission provide additional information on the ELF waves in the mentioned areas together with electron density and temperature. A brief discussion of the generation of these emissions by the so-called “fan instability” (FI) and beam instability is presented.

Mesoscale Convective Systems as a source of electromagnetic signals registered by ground-based system and DEMETER satellite

Mesoscale Convective Systems (MCS) are especially visible in the summertime, when there is an advection of warm maritime air from the West. Advection of air masses is enriched by water vapour, which source can be found over the Mediterranean Sea. In propitious atmospheric conditions, thus significant convection, atmospheric instability or strong vertical thermal gradient, lead to the development of strong thunderstorm systems. In this paper we discuss one case of MCS, which generated a significant amount of +CG, -CG and IC discharges. We have focused on the ELF (Extremely Low Frequencies,

Analysis of VLF/LF transmitter signals during the minimum of solar activity in the year 2018

<p>We report on VLF/LF transmitter signals observed in the year 2018 during the minimum of solar activity. Those signals were recorded in Graz (Austria) using INFREP (Biagi et al., Nat. Hazards Earth Syst. Sci., 11, 2011) and UltraMSK (Schwingenschuh et al., Nat. Hazards Earth Syst. Sci., 11, 2011) systems. This leads us to record fourteen transmitter signals in the frequency range between 19 kHz and up to 270 kHz. Six transmitter channels are common to both systems and are localized in Great-Britain (Anthorn, GBZ, 19.58kHz), Italy (Tavolara, ICV, 20.27kHz), Germany (Rhauderfehn, 23.4kHz,) and Island (Keflavik, NRK, 37.5kHz). Others are mainly LF broadcasting transmitters from Romania (Brasov, 153kHz), Luxembourg (Felsberg-Berus, 183kHz), Algeria (Berkaoui, 198kHz), Monte-Carlo (Roumoules, 216kHz) and Tchecki (Lualualei, 270kHz). In the year 2018, the solar activity decreased reaching its minimum in the end of 2019. We emphasize in this work on three aspects: (a) C-flares related to the solar activity, (b) Kp-index linked to the geomagnetic activity, and (c) seismic events in the southern part of Europe, i.e. Greece and Italy.  The dominant patterns observed on almost all transmitters are due to the solar flares. Geomagnetic activity is found to depend on the seasonal effect and mainly observed few weeks before and after the summer solstice in the northern hemisphere.  Few earthquakes occurred in the southern part of Europe, in Greece (6 events) and in Italy (2 events) with a magnitude of 5.5 Mw and depths less than 10 km. We discuss the disturbances of VLF/LF transmitter signals prior to EQs occurrences, and their links to external effects. Our results are compared to recent investigations of Zhang et al. (Radio Sci., 52, 2017) and Rozhnoi et al. (Ann. Geophys., 37, 2019) concerning, respectively, the spatial distribution of VLF transmitter signals recorded by Demeter satellite, and the solar X-flare effects on VLF/LF transmitter signals.</p>

The VLF transmitters' radio wave anomalies related to 2010 Ms 7.1 Yushu earthquake observed by DEMETER satellite and the possible mechanism

Earthquakes may disturb the lower ionosphere through various coupling mechanisms during their seismogenic and coseismic periods. The VLF signal radiated from ground-based transmitters will get affected when it penetrates the disturbed region in the ionosphere above the epicenter area, and this anomaly can be recorded by low earth orbit satellite under certain conditions. In this paper, the temporal and spatial variation of the Signal to Noise Ratio (SNR) of the VLF transmitter signal in the ionosphere over the epicenter of 2010 Yushu Ms 7.1 earthquake in China is analyzed. The results show that the SNR over the epicenter of Yushu earthquake especially in the southwestern region decreased (or dropped)revealed by one satellite revisit period before the main shock, which is consistent with the observed TEC anomaly at same time, implying that the decrease of SNR might be caused by the enhancement of TEC. A full-wave method was used to study the mechanism of the change of SNR before the earthquake. When the electron density in the lower ionosphere increases by four times, the electric field will decrease about 1 dB, indicating that the disturbed electric field decrease 20 % compared with the original electric field and vice versa. It can be concluded that the variation of electron density before earthquakes may be one important factor influence the variation of SNR.

Identifying a possible stratification phenomenon in ionospheric F2 layer using the data observed by the DEMETER satellite: method and results

Many studies have revealed the stratification phenomenon of the topside ionospheric F2 layer using ground-based or satellite-based ionograms, which can show direct signs of this phenomenon. However, it is difficult to identify this phenomenon using the satellite-based in situ electron density data. Therefore, a statistical method, using the shuffle resampling skill, is adopted in this paper. For the first time, in situ electron density data, recorded by the same Langmuir probe aboard the DEMETER (Detection of Electro-Magnetic Emission Transmitted from Earthquake Regions) satellite at different altitudes, are analyzed, and a possible stratification phenomenon is identified using the proposed method. Our results show that the nighttime stratification, possibly a permanent phenomenon, can cover most longitudes near the geomagnetic equator, which is not found from the daytime data. The arch-like nighttime stratification decreases slowly on the summer hemisphere and thus extends a larger latitudinal distance from the geomagnetic equator. All results, obtained by the proposed method, indicate that the stratification phenomenon is more complex than what has previously been found. The proposed method is thus an effective one, which can also be used in similar studies of comparing fluctuated data.

Precursory Response of Low Frequency Signals for Detection of Seismic Rapture in Indian Region

Recognition of seismic precursors is exigent task. Its study depends upon the environmental parameters, ground motion emissions (Low frequency signals), geological and tectonic structure. The theory of signal conductivity of two crust model between the epicenter region and above the ground surface calculated the amplitude enhancement of electromagnetic emissions. Extremely low frequency signals generate due to seismic emissions and penetrate the crystal layer to change the earth’s surrounding and upper atmosphere conditions. These outputs are used to correlate the seismogenic VLF signals (f=3 KHz), which are recorded by borehole antenna system. It is observed that the low frequency signals goes to vertically and accumulated as low conductivity medium in the outer most layer through which transmitted to the atmosphere. The seismogenic ULF emissions, DEMETER satellite data, TEC anomalies, ionospheric disturbances and bio-electric amplitude was recorded at places nearby active fault line in Indian region and it is used to recognized the pre- seismic behaviour. We have also observed the stimulus data (solar flux, audio frequency signals, or electric charge emissions) as abnormal signals. These relations are verified and correlated by statistical analysis with null hypothesis testing and power spectrum magnitude which is helping us to understand the precursory signature of earthquakes.