1 / 22

Институт земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН (ИЗМИРАН)

jfuller
Download Presentation

Институт земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН (ИЗМИРАН)

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Институт динамики геосфер РАН, 26-27 сентября 2011Семинар – совещание по проблеме «Межгеосферные взаимодействия»Теоретическаямодельгенерацииэлектрическихразрядов в атмосфере в результатевозмущенияглобальнойтоковойцепи в сейсмическомрегионе.В.М. Сорокин, Ю.Я. Ружин, В.Д. Кузнецов, А.К. Ященко Институт земного магнетизма, ионосферы и распространения радиоволн им. Н.В. Пушкова РАН (ИЗМИРАН) Возмущение электрического тока в глобальной электрической цепи над сейсмическим регионом может сопровождаться усилением электрического поля до его пробойного значения в нижней атмосфере. Турбулентность атмосферы приводит к возникновению случайных электрических разрядов. Эти разряды являются источником радиоизлучения. Найден спектр мощности электромагнитного излучения разрядов и его частотный спектр. Результаты расчетов сопоставлены с данными наблюдения ВЧ радиоизлучения в диапазоне 41 и 53 МГц, полученными на сети из четырех станций на о. Крит в течение трех лет. Источники излучения возникали в нижней атмосфере в течение нескольких дней до главного толчка землетрясения. Проведенные расчеты амплитудных и частотных характеристик излучения показали их согласие с данными наблюдения.

  2. Basic experimental results • Enhancement of seismic activity and typhoons produce DC electric field disturbances in the ionosphere with magnitudes up to 10 mV/m. • These disturbances occupy an area of the order of several hundred km in diameter over earthquake region. • DC electric field enhancements arise in the ionosphere from hours to 10 days before earthquakes. Chmyrev et al., Phys. Earth Planet. Inter. 1989; Sorokin et al., J. Atmos. Solar-Terr. Phys. 2005; Gousheva et al., Nat. Haz. Earth Syst. Sci. 2008, 2009. • Quasi-stationary electric field on the Earth surface in earthquake epicenter area does not exceed the value ~100 V/m. Vershinin et al., Atmos. Ionosph. Elect.-Magn. Phenom., 1999 • Pre-earthquake VHF electromagnetic radiation is generated in the atmosphere at altitudes 1 to 10 km over the quake zone. Vallianatos and Nomicos, Physics and Chemistry of the Earth 1998; Ruzhin et al., Proc. 15th Wroclaw EMC Symposium 2000; Ruzhin and Nomicos, Nat. Hazards 2007. • Seismic related disturbances in the troposphere create the conditions for over-horizon propagation of signals from ground-based VHF transmitters on the routes passing through the earthquake area. Fukumoto, Hayakawa, Yasuda, Seismo - Electromagnetics 2002; Fujiwara et al., G. R. L. 2004; Ohno et al., Seismo - Electromagnetics 2005.

  3. Outgoing long wave (8-12 μm) radiation anomalies in the atmosphere (10-12 km) with the thermal flux intensity from 4 to 80 Watts per square meter have been observed in the zones ~2.5 degrees in latitude and longitude over earthquake region weeks to month before large earthquake. Ouzounov et al., Tectonophysics 2007. Alterations in the total water vapor column and changes in aerosol parameters and ozone concentration in connection with large earthquakes have been reported. Dey et al., Adv. Space Res. 2004; Okadaet al., Adv. Space Res. 2004; Tronin, Seismo-Electromagnetics 2002; Tronin, Remote Sensing 2010. Concentration of charged soil aerosols in the atmosphere in seismic region increases by one to two orders of magnitude days to week before earthquakes. Similar effect was observed in intense radon (Rn222) and other radioactive substances outbursts on the eve of large earthquakes. Alekseev, Alekseeva, Nucl. Geophys. 1992; Virk and Singh, Geophys. Res. Lett. 1994; Heinke et al., Geophys. Res. Lett. 1994; Pulinets et al., Adv. Space Res. 1997; Yasuoka et al., Appl. Geochem. 2006; Omori et al., Nat. Haz. Earth Syst. Sci. 2007.

  4. Model of DC electric field penetration from the lithosphere into the ionosphereThis model assumes that the field source is situated in the lithosphere and the field is transferred through the atmospheric layer with altitude dependent electric conductivity. The layer is a part of the closed global atmosphere-ionosphere electric circuit at given electric field on the ground. 1. Earth surface 2. Conductive layer of the ionosphere 3. Lithosphere source of electric field. 4. Electric field on the ground. 5. DC electric field in the ionosphere 6. Atmosphere – ionosphere electric circuit. Pulinets et al., J. Atm. Solar-Terr. Phys. 2003; Grimalsky et al., J. Atm. Solar–Terr. Phys. 2003; Denisenko et al., Nat. Hazards Earth Syst. Sci. 2008 Ampferer et al., AnnalesGeophysicae 2010; Electric field in the ionosphere This model gives maximum magnitude of the electric field in the ionosphere not exceeding 0.001 mV/m when the ground field value is ~100 V/m and therefore seems to be impracticable.

  5. The key role in seismo-ionospheric interaction belongs to electromotive force (EMF) in the lower atmosphere. The external current of EMF is excited in a process of vertical atmospheric convection and gravitational sedimentation of charged aerosols. Aerosols are injected into the atmosphere due to intensified soil gas elevation in the lithosphere during the enhancement of seismic activity. 1. Atmospheric convection and turbulent diffusion. 2. Gravitational sedimentation. 3. Atmospheric radioactivity. 4. Soil gases. 5. Conduction electric current. 6. Electromotive force.

  6. Model of DC electric field generation in the ionosphere by seismic related Electro Motive Force (EMF) in the lower atmosphereInclusion of EMF into the atmosphere – ionosphere electric circuit leads to DC electric field growth up to 10 mV/m in the lower ionosphere. Sorokin V. and Yaschenko A., Adv. Spase. Res., 2000. Sorokin et al., J. Atmos. Solar-Terr. Phys. 2001. Sorokin et al., J. Atmos. Solar-Terr. Phys. 2005. Sorokin et al., Natural Hazards and Earth System Sciences. 2005. Sorokin et al., Natural Hazards Earth System Sci. 2007. Sorokin and Chmyrev. Atmosphere–ionosphere electrodynamic coupling. Springer. 2009. 1. Earth surface 2. Conductive layer of the ionosphere 3. External electric current in the lower atmosphere 4. Conductivity electric current in the atmosphere – ionosphere circuit 5. DC electric field in the ionosphere 6. Field - aligned electric current 7. Charged aerosols injected into the atmosphere by soil gases Electric field in the ionosphere

  7. The ionization-recombination processes Equilibrium values of ion number densities are determined by the recombination process and the adhesion to aerosols in the atmosphere. The light single-charged ions and the heavy ions are produced as a result of light ions adhesion to aerosols in the atmosphere near the Earth’s surface. Sorokin et al., Natural Hazards Earth System Sci. 2007. EMF electric current and charge densities:

  8. Spatial distribution of external current, atmospheric conductivity, aerosols and DC electric field in the convective atmosphere is described by the self-consistent set of nonlinear equations :

  9. Input parameters of model are the atmosphere turbulence and convection, atmosphere radioactivity and aerosols density near the ground. A source of ionization defines the conductivity in the near ground atmospheric layer Radioactive elements such as radon, radium, thorium, actinium and their decay products enter the atmosphere together with soil gas. Sorokin et al., J. Atmos. Solar-Terr. Phys. 2001. Sorokin et al., Natural Hazards Earth System Sci. 2007. The vertical distribution of ion production rate is a result of atmospheric absorption of gamma radiation and alpha particles from the decay of radioactive elements being constituents of the atmospheric radioactivity. Curves 1,2 and 3 correspond to different levels of atmospheric radioactivity growing from 1 to 3.

  10. Calculation result of the altitude dependences of external electric current and atmospheric conductivity at the epicenter of disturbed region at different levels of atmospheric radioactivity.Sorokin et al., Natural Hazards Earth System Sci. 2007. • External current is formed as a result of: • convective transfer of charged aerosols, • ionization of lower atmosphere by radioactive sources, • adhesion of electrons to molecules, • interaction of charged ions with charged aerosols

  11. An examples of large magnitude DC electric field distribution in the lower atmosphere normalized to the breakdown electric field Sorokin et al., J. Atmos. Solar-Terr. Phys. 2011. At definite conditions the seismic related DC electric field can reach the breakdown value in some region of the atmosphere (marked out by red in the figure below).

  12. Fluctuations of the atmosphere density and DC electric field reaching the breakdown value in turbulent vortices cause the formation of random electrical discharges in the disturbed region

  13. Generation of VHF radio emissions in the atmosphereSorokin et al., J. Atmos. Solar-Terr. Phys. 2011. Coordinates used for the calculation of characteristics of electromagnetic radiation. Maxwell equations

  14. Frequency spectrum of the electromagnetic radiation generated by random electric discharges. Green function Power spectrum of the electromagnetic radiation of discharges, which is observed during an interval of time T, is defined by the formula: The frequency spectrum of electric field of radiation is defined by the power spectrum:

  15. Discharge is the infinitely thin pulse linear current. Their spatial temporal distribution is chosen in the form: The model of distribution of linear current in a discharge is chosen in the form: Iudin and Trakhtengerts, Radiophysics and Quantum Electronics, 2001. is the square of cross-section of discharge.is the length of discharge. is the velocity of current wave in the discharge. The spectrum of electric field of radiation at a distance from the epicenter of disturbed region of the atmosphere is the mean-square value of linear current amplitudes of discharges in the cells, is the amplitude of linear current of discharge in the cell with number k. Spatial distribution of the probability density of discharges.

  16. Calculation result of the spectrum of electromagnetic radiation at distance 300 km from the epicenter of disturbed area. Radiation is formed by random discharges in the disk-like region. This region has radius 40 km and thickness 1 km. The centre of region is located at the altitude 6 km in the atmosphere. The vertical sections of line are denoted the experimental data.

  17. Calculation result of the spatial distribution of amplitude of the electromagnetic radiation at a frequency 50 MHz.Radiation is formed by random discharges in the disk-like region. The centre of region is located at the altitude 6 km in the atmosphere.

  18. VHF radiations are found to have occurred for several days before an EQ. Their duration reaches several days. If VHF electromagnetic radiation is propagated on the distance more than a wave length, the condition of optical propagation is fulfilled. Consequently, it is possible to receive the signal at distance of the order of 300 km just in the case if its source is located in the atmosphere above Earth’s surface. The region of generation of VHF electromagnetic radiation is at the altitudes of the order of several kilometers above EQ epicenters located behind the horizon. Ruzhin and Nomicos, Nat. Hazards 2007.

  19. The pre-seismic VHF signals for the November 21, 1992 EQ (M = 6.0).The output voltage of the receivers presented is given on the vertical axis. Full scale is 2000 mV. N, I, H and D represent the observing stations of Nipos, Ierapetra, Heraklio and Drapania, respectively, forming Crete monitoring station.Vallianatos and Nomicos, Physics and Chemistry of the Earth 1998

  20. Pre-earthquake DC electric field reaching the breakdown value initiates numerous chaotic electrical discharges and related phenomena in the lower atmosphere • Chaotic electrical discharges. • Heating of atmosphere in the discharge region and the generation of outgoing long wave (8-12 μm) radiation. • Broadband electromagnetic VHF emission observable on the ground and in space. • Airglow in visible range of wavelengths. • Refraction and scattering of VHF radio waves in the troposphere providing the reception of VHF transmitter signals by over-horizon ground-based receivers and by satellites. • Growth of ozone concentration in the disturbed region.

  21. Atmosphere Above Japan Heated Rapidly Before M9 Earthquake (http://www.technologyreview.com/blog/arxiv/26773/)Infrared emissions above the epicenter increased dramatically in the days before the earthquake in Japan (D. Ouzounov et al., 2011)

  22. Заключение Квазистатическое электрическое поле возмущения тока в глобальной цепи может достигать пробойного значения в нижней атмосфере над сейсмическим регионом. Источником возмущения тока служит ЭДС между поверхностью Земли и нижней атмосферой, которая возникает в результате вертикального переноса и гравитационного оседания заряженных аэрозолей, инжектируемых в атмосферу почвенными газами в период сейсмической активности. Область атмосферы, в которой электрическое поле достигает пробойного значения расположена на высотах от 1 до 10 км. Турбулентные вихри в этой области формируют случайные электрические разряды, которые служат источником электромагнитного излучения. Амплитуда спектра электромагнитного излучения в УКВ диапазоне составляет величину . Результаты расчета характеристик электромагнитного излучения согласуются с данными наземных наблюдений УКВ радиоизлучения в период подготовки землетрясений.

More Related