22 research outputs found
Radon and ionosphere monitoring as a means for strong earthquakes forecast
The relation between radon emanation in seismically active regions and variations of the ionosphere parameters is considered. The quasistationary anomalous electric field generated in the near-ground layer of the atmosphere due to
radon and metallic aerosols emanation is proposed as the main agent of the seismo-ionospheric coupling mechanism. The effects of the quasistationary electric field penetrated into the ionosphere are considered theoretically and compared with the experimental results. The comparison confirms the proposed conception of the seismo-ionospheric coupling
The Nocturnal Positive Ionospheric Anomaly of Electron Density as a Short-Term Earthquake Precursor and the Possible Physical Mechanism of Its Formation
Nonlinear broadband doubling of the extraordinary wave frequency in inhomogeneous magnetoactive plasma
The nonlinear resonance doubling of radio wave frequencies in inhomogeneous plasma is studied as applied to the ionosphere under the conditions of the phase synchronism between an extraordinary pump wave and its second harmonic. The synchronism is not related to plasma resonances, but is determined by the magnetic field and plasma electron density in the transparency region. The generation efficiency of the second harmonic of a transversely propagating wave is calculated for a wide frequency band lying higher than the lower hybrid resonance frequency. It is shown that this effect is physically analogous to the generation of the second harmonic of laser radiation in a nonlinear crystal. The generation efficiency of the second harmonic is determined for inhomogeneous ionospheric plasma in which the synchronism condition is satisfied in a limited frequency range. It is shown that this effect can be used for remote nonlinear diagnostics of the upper ionospheric plasma, in which the characteristic size of the synchronism region can reach several kilometers. It is proposed to use a combination of satellite and ground-based ion probes in experiments on transionospheric probing. Even if the frequency of the wave emitted from the satellite is lower than the critical frequency in the ionosphere, the frequency of its second harmonic can exceed the critical frequency, so that it can be recorded by a ground-based ion probe or a specially designed receiver. The reflected second-harmonic signal can also be detected at the satellite by using a broadband radio-frequency spectrometer. © 2014 Pleiades Publishing, Ltd
Nonlinear broadband doubling of the extraordinary wave frequency in inhomogeneous magnetoactive plasma
The nonlinear resonance doubling of radio wave frequencies in inhomogeneous plasma is studied as applied to the ionosphere under the conditions of the phase synchronism between an extraordinary pump wave and its second harmonic. The synchronism is not related to plasma resonances, but is determined by the magnetic field and plasma electron density in the transparency region. The generation efficiency of the second harmonic of a transversely propagating wave is calculated for a wide frequency band lying higher than the lower hybrid resonance frequency. It is shown that this effect is physically analogous to the generation of the second harmonic of laser radiation in a nonlinear crystal. The generation efficiency of the second harmonic is determined for inhomogeneous ionospheric plasma in which the synchronism condition is satisfied in a limited frequency range. It is shown that this effect can be used for remote nonlinear diagnostics of the upper ionospheric plasma, in which the characteristic size of the synchronism region can reach several kilometers. It is proposed to use a combination of satellite and ground-based ion probes in experiments on transionospheric probing. Even if the frequency of the wave emitted from the satellite is lower than the critical frequency in the ionosphere, the frequency of its second harmonic can exceed the critical frequency, so that it can be recorded by a ground-based ion probe or a specially designed receiver. The reflected second-harmonic signal can also be detected at the satellite by using a broadband radio-frequency spectrometer. © 2014 Pleiades Publishing, Ltd
Deterministic Variability of the Ionosphere on the Eve of Strong (M ≥ 6) Earthquakes in the Regions of Greece and Italy According to Long-Term Measurements Data
Precursory phenomena observed in the total electron content measurements before great Hokkaido earthquake of September 25, 2003 (M = 8.3)
Total electron content variations in the ionosphere before the Colima, Mexico, earthquake of 21 January 2003
En la actualidad se encuentra bien establecida la existencia de variaciones ionosféricas anómalas asociadas con el proceso de preparación de sismos fuertes (M>5). Con el fin de comprobar posibles variaciones ionosféricas que estuvieran relacionadas con el reciente temblor de Colima, México, M=7.8, del 21 de enero de 2003, se analizaron los datos de 5 receptores GPS de la red del Instituto Nacional de GeografÃa, EstadÃstica e Informática (INEGI) de México. Se encontró que el TEC obtenido a partir de estos datos muestra anomalÃas importantes de dos a tres dÃas antes del impacto sÃsmico, mientras que el coeficiente diario de correlación cruzada calculado para diferentes pares de receptores GPS presenta una caÃda importante dentro de un intervalo de uno a cinco dÃas antes de dicho impacto. Por otra parte, la distribución horizontal (latitud-longitud) de las desviaciones del TEC con respecto a la media mensual para el dÃa y la hora del sismo tuvo su máximo en un punto cercano a la proyección vertical en la ionosfera del epicentro del mismo. Hemos concluido a partir de esto que las variaciones observadas en la ionosfera durante el proceso de preparación y de realización del sismo pueden ser consideradas como posibles precursores de corto plazo del mismo
A Comparative Analysis for Detecting Seismic Anomalies in Data Sequences of Outgoing Longwave Radiation
A spatial analysis on seismo-ionospheric anomalies observed by DEMETER during the 2008 M8.0 Wenchuan earthquake
International audienceThis paper examines seismo-ionospheric anomalies (SIAs) observed by the French satellite DEMETER (Detection of Electro-Magnetic Emissions Transmitted from Earthquake Regions) during the 12 May 2008 M8.0 Wenchuan earthquake. Both daytime and nighttime electron density (Ne), electron temperature (Te), ion density (Ni) and ion temperature (Ti) are investigated. A statistical analysis of the box-and-whisker method is utilized to see if the four DEMETER datasets 1–6 days before and after the earthquake are significantly different. The analysis is employed to investigate the epicenter and three reference areas along the same magnetic latitude discriminating the SIAs from global effects. Results show that the nighttime Ne and Ni (daytime Ti) over the epicenter significantly decrease (increase) 1–6 days before the earthquake. The intersections of the global distribution of the significant differences (or anomalous changes) in the nighttime Ne, the nighttime Ni, and the daytime Ti 1–6 days before and after the earthquake specifically appear over the epicenter, which strongly suggests that DEMETER observes SIAs of the 2008 M8.0 Wenchuan earthquake