Electrodynamic Model of the Atmosphere-Ionosphere Coupling

1. JpGUMeeting 2013Japan Geoscience Union Meeting 2013, May 19 - 24, 2013, MakuhariMesse, Japan.Electrodynamic model of the atmosphere – ionosphere couplingV.M. Sorokin Puskov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Russian Academy of Sciences, Troitsk, Moscow, 142190, RUSSIA. This report presents a summary of models for LAI coupling by quasi-static electric field and a brief description of the formation mechanisms of electromagnetic and plasma disturbances in near-Earth space at the preparatory phase of earthquakes(EQs). Spatial distribution of this field has a horizontal scale of 100 – 1000 km and the temporal scale of field is (1 – 10) days.

2. Basic experimental results • Enhancements 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 an EQ region. • DC electric field enhancements arise in the ionosphere from hours to 10 days before EQs. 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. • Computer simulation shows that pre-seismic TEC variations occur by a quasi-static electric field disturbance in the ionosphere with amplitude (3 – 9) mV/m . Zolotov et al., 7th International Conference "Problems of Geocosmos" 2008 Namgaladze et al., Geomagn. Aeron. 2009 Klimenko et al., Adv. Space Res. 2011; 2012 • Pre-earthquake VHF electromagnetic radiation is generated by electric discharges in the troposphere at altitudes (1 – 10) km over the EQ zone. Vallianatos and Nomicos, Phys. Chem. Earth 1998; Ruzhin et al., Proc. 15th Wroclaw EMC Symposium 2000; Ruzhin and Nomicos, Nat. Hazards 2007.

3. Basic experimental results (continuation) • Quasi-static electric fields on the Earth surface in an EQ epicenter area do not exceed the background value ~100 V/m. The spike of electric field reaching (1 – 10) kV/m in the local area has a duration over 10 min. Jianguo, Acta Seismol. Sin., 1989 Vershinin et al., Atmos. Ionosph. Elect.-Magn. Phenom., 1999 Nikiforova and Michnovski, IUGG XXI General Assem. 1995 Hao et al., J. Earthquake Pred. Res., 2000 Rulenko, Vulcanology and Seismology, 2000 • Lithosphere activity stimulates the processes of active substances injection in the atmosphere during days and weeks before EQs. Number density of charged aerosols enhancement of one – two order. Atmosphere radioactivity level is increased by radon and other radioactive elements in several times. King, J. Geophys. Res., 1986 Alekseev and Alekseeva, Nucl. Geophys., 1992 Virk and Singh, Geophys. Res. Lett., 1994 Heinke et al., Geophys. Res. Lett., 1994 Voitov and Dobrovolsky, Izvestiya AN SSSR, Fizika Zemli, 1994 Igarashi et al., Science, 1995 Pulinets et al., Adv. Space Res. 1997 Boyarchuk, Proceed. of RAS, Afmos. Ocean. Phys. 1997 Yasuoka et al., Appl. Geochem 2006; Omori et al., Nat. Hzards Earth Syst. Sci. 2007

4. DC electric field which were observed onboard the "IB -1300" satellite within the 15-min interval before the earthquake occurred on January 12, 1982 at 17.50.26 UT . Satellite measurements of seismic related quasi-static electric field in the conjugated regions Chmyrevet al., Phys. Earth Planet. Inter. 1989.

5. Satellite measurements of seismic related quasi-static electric field in the conjugated regions Gousheva et al., Nat.Haz.Earth Syst.Sci., 2009. Satellite measurements of seismic related quasi-static electric field in the conjugated regions Gousheva et al., Nat.Haz.Earth Syst.Sci., 2009. • DC electric field which were observed onboard the "IB -1300" satellite over the 85 hours before the earthquake occurred on August 29, 1981at 07:41:51UT.

6. The trajectory of movement of tropical storm (WINONA) in a northwest part of Pacific Ocean (bold curve). Satellite measurements of quasi-static electric field in the conjugated regions over typhoonIsaev et al., Space Reseach, 2002. The satellite orbit over the tropical storm.

7. Variations of two horizontal components of DC electric field Ex and Ey along the satellite orbit. An arrow shows the moment when the satellite passed at minimum distance from the strong tropical storm center. • DC electric field which were observed onboard the “COSMOS -1809" satellite over the zone of large-scale tropical depression in its initial stage on January 17, 1989

9. Vertical component of quasi-static electric field on the Earth’s surfaceVershinin et al., 1999 • Electric field at distance 130 km from epicenter of EQ M=6.1 • Simultaneousobservations of electric field at distances 200 km and 220 km from epicenter of EQ M=7

10. Electrodynamical LAI model is based on the assumption that the current source is situated in the near ground atmospheric layer including the surface. The key role in seismo-ionospheric interaction belongs to the 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.

11. Model of DC electric field generation in the ionosphere by seismic-related Electro Motive Force (EMF) in the lower atmosphere 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

12. Inclusion of EMF into the atmosphere – ionosphere electric circuit leads to DC electric field growth up to 10 mV/m in the lower ionosphere. Limitation of the field on the surface is explained by the mechanism of feedback between the electric field and the causal external currents. Such a feedback is caused by the formation of a potential barrier on the ground-atmosphere boundary. Sorokin et al., JASTP, 2001 Sorokin et al., JASTP, 2005 Sorokin et al., Nat. Haz. and Earth Sys. Sci., 2005 Sorokin et al., Adv. Space Res., 2006Sorokin et al., Nat. Haz. and Earth Sys. Sci., 2007 Sorokin and Chmyrev, The Atmosphere and Ionosphere, 2010 Simple estimation of electric field in the ionosphere We have found the mechanism for enhancement of conducting electric current with altitude and the mechanism for limitation of electric field on the ground surface. This model can be used to explain the LAI coupling because it satisfies the experimental data.

13. Feedback formation between external current and vertical component ofelectric field on the Earth surface results in limitation of electric fieldSorokin et al., JASTP, 2005 1 - Positive charged aerosols. 2 - Negative charged aerosols. 3 - Elevated soil gases. 4 - The Earth surface. This feedback is produced by the potential barrier for charged particle at its transfer from ground to the atmosphere Value of electric field on the Earth’ surface has to be in the following limits: is the ionosphere potential, is the atmosphere conductivity, is the limit field,

14. The theory of electric field limitation by the feedback between the electric field and the causal external currents on the Earth’s surface. Calculation result of the dependence of vertical electric field value on the Earth surface on the magnitude of EMF external current Sorokin et al., JASTP 2005;

15. The altitude dependences of source of ionization, atmosphere conductivity and external electric current over the center of disturbed region.Sorokin et al., Nat. Haz. and Earth Sys. Sci., 2007 Calculation results based on the theory of quasi-static electric field generation by EMF formation in the global circuit.

16. Calculation results of the spatial distribution of horizontal electric field in the ionosphere and vertical electric field near the Earth surface over the ellipsoidal fault Sorokin et al., Nat. Haz. Earth Sys. Sci.,2005

17. An example of calculation of the quasi-static electric field spatial distribution in the atmosphere normalized to the breakdown electric field Sorokin et al., JASTP, 2011 Sorokin et al., The frontier of earthquake prediction studies, 2012 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 figures).

18. Application of electrodynamic LAI coupling model for interpretation of experimental data. • Below it is presented the examples of calculation of plasma and electromagnetic effects occurring by charged aerosols injection in the atmosphere during growth of seismic activity using above mentioned theory.

19. Seismic related large-scale modification of the ionosphere F layer Formation mechanism of the local large-scale seismo-ionospheric anomalies in Total Electron Content (TEC) is proposed. The total TEC variations caused by two following processes:• Plasma drifts by electric field in the ionosphere, • Ionosphere modification by electric current heating. Ruzhin et al., Geomagn. and aeronomy, 2013 (to be published) • 1. Earth’s surface. 2. Conducting layer of the ionosphere. 3. Charged aerosols injection by soil gases. 4. Region of EMF formation in the near ground atmosphere. 5. Perturbation of electric current in the global circuit. TEC disturbance due to heating of the ionosphere by electric current. TEC disturbance due to plasma drift in the electric field.

20. Horizontal distribution of charged aerosols number density in the near ground level. Horizontal distribution of zonal electric field in the ionosphere. Example of TEC calculation formed by plasma drift and ionosphere heating over seismic region. Plasma drift leads to the bipolar disturbance of TEC while ionosphere heating leads to the disturbance of like-sign. The combination of these effects allows explain existence of two types of TEC disturbances both bipolar and like-sign ones. Horizontal distributions of the relative TEC disturbances. Horizontal distribution of the ionosphere temperature.

21. Seismic related large-scale disturbances of the ionosphere E layer formed by charged aerosols injection. VLF/LF radio signal anomalies associated with earthquakes Specificvariationsoftheamplitudeandphaseof VLF signalswereobservedthetracesofwhichwereclosetotheepicentresoftheforthcomingearthquakes. Thetransmittersand receivers of these waves ((20 – 50) kHz) propagating in the Earth-ionosphere waveguide were located on the ground. Biagiet al., 2004;; Hayakawa 2007 During a few days prior the earthquakes there were anomalies in the form of the decreases of the amplitude and phase of the VLF signals. In the spectra of quiet as well as disturbed days the main maximums correspond to the period of 30-35 min. Moreover, during seismic activity there is an evidence of appearance of maximums with 20-25 min and 10-12 min. Rozhnoi et al., 2005, 2007

22. Scheme of formation of the inhomogeneity in the lower ionosphere caused by perturbation of the electric current in the global circuit due to charged aerosols injection to the atmosphere in the epicentral zone. Sorokin and Pokhotelov (to be published) • Injection of the charged aerosols by the soil gazes. • The region of the convective transport of the charged aerosols and formation of the EMF. • Perturbation of the conductive electric current. • Electric current in the ionosphere. • Ionospheric conductive layer. • Plasma inhomogeneity in the lower ionosphere.

23. Model for electron number density distribution in the ionosphic E - region disturbed by the electric current flowing into the ionosphere from the atmosphere caused by charged aerosols injection.Sorokin et al., JASTP, 2006 Self-consistent system of non-linear equations for ion number density and electric field in the lower ionosphere:

24. The values of periods corresponding to spectrum maximums of oscillations caused by enhancement of electric current in the lower ionosphere . Sorokin and Pokhotelov, ASR, 2013 (to be published). Circles – the electric field is zero. Squares – the electric field equals 9 mV/m.

25. Model for electron number density distribution in the D layer of the ionosphere disturbed by the electric current flowing from the atmosphere to the ionosphereLaptukhov et al., Geomagn. Aeronom., 2009 Self-consistent system of non-linear equations for electron and ion number density, temperature and the electric field:

26. Seismic related small-scale disturbances of the ionosphere formed by charged aerosols injection.Satellite data of the small-scale plasma fluctuations. Example of observation of the small-scale plasma irregularities in the disturbed magnetic tube over seismic region. Chmyrev et al., JASTP, 1997. Example of observation of the small-scale plasma irregularities over typhoon zone. Sorokin et al., JASTP, 2005.

27. Acoustic Gravity Wave (AGW) instability related to DC electric field enhancement in the lower ionosphereThe formation of large enough DC electric field in the ionosphere exceeding a definite threshold value leads to an instability of acoustic-gravity waves and the generation of periodic or localized ionospheric structures in a form of solitary dipole vortices or vortex chains and associated plasma density and electric conductivity disturbances in the ionosphere. Sorokin et al., JASTP, 1998; Chmyrev and Sorokin, JASTP, 2010 The frequency dependence of the refraction indexand the absorption coefficientof acoustic-gravity wave in the ionosphere in the presence of an external electric field. Vortex formation.

28. Examples of satellite observations of ULF magnetic field oscillations, electron number density fluctuations and ELF electromagnetic emissions caused by the formation of the ionosphere conductivity irregularitiesChmyrev et al., Phys. Earth Planet. Inter., 1989; Chmyrev et al., JASTP, 1997 1. Earthquake. 2. Irregularities of the ionosphere conductivity. 3. Field-aligned currents and irregularities of electron number density. 4. Satellite trajectory crossing the disturbed region. ULF magnetic field. Electron number density fluctuations. ELF electromagnetic emissions

29. The generation mechanism of electromagnetic ELF wave precursors to EQs. Excitation of horizontal small-scale irregularities of electric conductivity in the lower ionosphere is a key factor for ELF wave radiation to the ionosphere. Borisov et al., JASTP, 2001 These waves are generated by an interaction of thunderstorm related EM radiation with small-scale plasma irregularities excited in the lower ionosphere before EQs. These EM pulses radiated by lightning discharges and propagated in sub-ionospheric waveguide with small attenuation are scattered by the irregularities and re-emitted into the upper ionosphere.

30. Other applications of the model for periodic disturbances of electric conductivity in the lower ionosphere. • Generation of the narrow-band gyrotropic waves and associated magnetic field oscillations on the Earth surface through the interaction of background electromagnetic noise with periodic inhomogeneities of electric conductivity in the ionosphere over seismic region. • Sorokin and Hayakawa, JGR, 2008 • Interpretation in terms of gyrotropic waves of Schumann-resonance-like anomalous line emissions observed before earthquakes. • Hayakawa et al., IEEJ, 2011

31. Pre-EQ DC electric field reaching the breakdown value initiates numerous chaotic electrical discharges and related phenomena in the lower atmosphereSorokin et al., The Frontier of Earthquake Prediction Studies, 2012 • Chaotic electric discharges. • Heating of the atmosphere in the discharge region and the generation of outgoing long wave (8-12 μm) radiation. • Broadband electromagnetic VHF emission. • Airglow in visible range of wavelengths. • Refraction and scattering of VHF radio waves in the troposphere providing the over-horizon reception of ground-based VHF transmitter signals.

32. Calculated spectrum of VHF electromagnetic radiation at distance 300 km from the epicenter of disturbed area The radiation source is modeled by the disk-like random discharges region with radius 40 km and thickness 1 km located at 6 km altitude in the atmosphere. Two vertical lines on the curve in figure show the spectral densities observed in experiment (Ruzhin and Nomicos, 2007). Sorokin et al., JASTP, 2011

33. Calculation results of the over horizon spatial distribution of mean value of scattered electric field. The transmitter monochromatic wave is scattered on the random electric discharges. These discharges are occurred in the region of troposphere in which electric field reaches breakdown value. Axially symmetric scattering region Ellipsoidal scattering region 100km X 100km 100km X 600km

34. The scheme of processes producing the atmosphere – ionosphere couplingSorokin and Hayakawa, MAS, 2013.

35. Conclusion. Experimental data and modeling show that the quasi-static electric field in the ionosphere can reach a value up to 10 mV/m during several days before EQs and, at the same time, it does not exceed the background value on the Earth’s surface. Model for electric field generation by including an additional EMF connected with charged aerosols injection in the global circuit allow us to explain above-mentioned experimental data. Electrodynamic model allows us to make calculations of measured parameters of plasma and electromagnetic precursors.