Electromagnetic and plasma disturbances caused by impact to the ionosphere Valery M. Sorokin Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radio Wave Propagation (IZMIRAN), Russian Academy of Sciences, IZMIRAN, Troitsk, Moscow Region, , Russia The ionosphere is disturbed by earthquakes, volcanic eruptions, typhoons, thunder-storms, explosions. Disturbing factors of these processes are the atmospheric perturbations, electric currents, electromagnetic radiations, and increase of radioactivity level, charge aerosols transport. Numerous observations of anomalous plasma and electromagnetic phenomena in the ionosphere above the regions of seismic and meteorological activity are evidence that intense processes in these regions influence the state of the ionosphere during periods of from several hours to several dozens of days.

Global Seismic Hazard Map

Kamchatka peninsula is seismic region 29 active volcanoes annually produce 3 to 4 eruptions of explosive type

Klyuchevskoy Volcano eruption in northern Kamchatka. This is the photograph taken by NASA from a space shuttle, which shows the ash cloud. Volcanic ash reach the altitudes above 15 km and spread the distance up to several thousand km from their source filling the air space over the ocean. Volcanic ash is extremely hazardous to flying jet aircraft.

Photo of typhoon

Photo of earthquake region

Thunderstorms in the atmosphere and in the ionosphere

In this report it is presented the electrodynamic model of atmosphere - ionosphere coupling at the stages of earthquake, typhoon and development that allows to explain numerous effects in space plasma by a single cause - an enhancement of DC electric field in the ionosphere. This field caused by electric current flowing in the ionosphere is controlled by dynamics of the lithosphere and the atmosphere processes through variations of external electric current in the lower atmosphere. In this report it is presented the electrodynamic model of atmosphere - ionosphere coupling at the stages of earthquake, typhoon and volcanic eruptions development that allows to explain numerous effects in space plasma by a single cause - an enhancement of DC electric field in the ionosphere. This field caused by electric current flowing in the ionosphere is controlled by dynamics of the lithosphere and the atmosphere processes through variations of external electric current in the lower atmosphere.

Physical base of new methods for monitoring of earthquake, typhoon and volcanic activity is the electrodynamic model of atmosphere – ionosphere coupling. 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. Field - aligned electric current 6. Satellite trajectory 7. Charged aerosols injected into the atmosphere by soil gases

The external current is excited in a process of vertical atmospheric convection and gravitational sedimentation of charged aerosols. Aerosols are injected into the atmosphere due to intensifying soil gas elevation in the lithosphere during the enhancement of seismic activity. Its inclusion into the atmosphere – ionosphere electric circuit leads to DC electric field increases up to 10 mV/m in the ionosphere. Aerosol transferring can be accompanied by increasing of atmospheric radioactivity.

Calculation result of the altitude dependence of ion production rate above epicenter of disturbed region at different level of the atmosphere radioactivity. The ionization is produced by gamma quantum and alpha particle of radioactive decay. This function is used in the analyses of ion and aerosol kinetics in presence of atmospheric radioactivity.

Calculation results of the altitude dependences of atmosphere conductivity at the epicenter of disturbed region. On the left panel it is presented atmosphere conductivity at the different level of atmospheric radioactivity. On the right panel it is presented atmosphere conductivity at the different number density of charged aerosols over Earth’s surface.

The altitude dependences of external electric current above the epicenter of disturbed region at the different level of atmospheric radioactivity, calculated by our model. 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

Atmospheric electric field variations with time scale exceeding one day at the distances within tens to hundreds kilometers from the epicenter of disturbed region during seismically active period never exceed the background magnitudes ~ V/m. The mechanism of feedback between disturbances of vertical electric field and the causal external currents near the Earth surface can explain such limitation.

Scheme of the feedback formation between external current and vertical electric field on the Earth surface 1 - Positive charged aerosols. 2 - Negative charged aerosols. 3 - Elevated soil gases. 4 - The Earth surface. Intensified soil gas elevation increases aerosols injection into the atmosphere. The feedback is produced by the potential barrier for charged particle at its transfer from ground to the atmosphere

Dependence of vertical electric field on the Earth surface on the magnitude of external current

DC electric field calculated for axially symmetric distribution of the external electric current Upper panel: Horizontal DC electric field in the ionosphere along and across the plane of magnetic meridian. Angle of magnetic field inclination is Middle panel: Vertical component of DC electric field on the Earth surface. Lower panel: Normalized vertical component of external current on the Earth surface.

Altitude dependence of ratio of electric field to breakdown field. On possibility of lightning discharges occurring above seismic region. The lightning discharges can be occurred on the altitudes where this ratio more than unit. Calculation result of the altitude dependence of DC electric field in the atmosphere – ionosphere layer

Example of the spatial distributions of DC electric field calculated for the axially symmetric external electric current Upper panel: Horizontal component of DC electric field in the ionosphere. Angle of magnetic field inclination is Lower panel: Vertical component of DC electric field on the ground.

Spatial distribution of DC electric field in the ionosphere calculated for the different angles of magnetic field inclination

Spatial distribution of the horizontal component of electric field in the ionosphere and the vertical component of electric field on the Earth surface over fault in the form an ellipse.

Examples of satellite observations of DC electric field DC electric field observed by the "ICB -1300" satellite within 15-min interval before the earthquake occurred on January 12, 1982 at UT. DC electric field observed by the “COSMOS -1809" satellite over the zone of large-scale tropical depression in its initial stage on January 17, 1989

The trajectory of movement of tropical storm (WINONA) in a northwest part of Pacific Ocean (bold curve). The satellite orbit over the tropical storm.

The dissipative instability of acoustic-gravity waves in the ionosphere The plasma density variations in the wave result in growth of the conductivity disturbances and the Joule heating connected with the disturbed currents. As a result the conductivity irregularities with the horizontal spatial scale are excited in the lower ionosphere. The frequency dependence of the refraction index and the absorption coefficient of acoustic-gravity wave in the ionosphere in the presence of an external electric field.

Formation of field-aligned currents and plasma irregularities in the upper ionosphere as a result of AGW instability in the lower ionosphere. The excitation of horizontal spatial structure of conductivity in the lower ionosphere results in the formation of field align currents and plasma layers stretched along the geomagnetic field.

Examples of satellite observations of ULF magnetic field oscillations and electron number density fluctuations 1. Irregularities of ionosphere conductivity. 2. Irregularities of electron number density stretched along geomagnetic field. 3. Field-aligned currents. 4. Satellite trajectory crossing the disturbed region. a). ULF magnetic field oscillations observed onboard the "ICB -1300" satellite within the 15- min interval before the earthquake occurred on January 12, 1982 at UT. b). Electron number density fluctuations observed onboard the “COSMOS- 1809” satellite within the 3.4 hour interval before aftershock of the Spitak earthquake on January 20, 1989 at UT.

Satellite data of the pre seismic plasma and electromagnetic effects

The excitation of horizontal small-scale irregularities of electric conductivity in the lower ionosphere can be used as a basis for generation mechanism of electromagnetic ELF precursors to earthquakes. These waves appear due to interaction of thunderstorm related EM radiation with small-scale plasma irregularities excited in the lower ionosphere before earthquakes. EM pulses are generated by lightning discharges and propagate in the sub-ionospheric wave guide with small attenuation in ELF range

Gyrotropic waves generation in the lower ionosphere by polarization currents which occurs due to interaction of background electromagnetic noise and conductivity irregularities.

Calculation result of the narrow-band spectrum of ULF oscillations generated over seismic regions. Relative spectrum on the Earth surface.

Calculation result of the spatial distribution of electron number density in the E layer of ionosphere at flowing electric current from the atmosphere to the ionosphere.

Altitude distribution of the electron number density in the center of disturbed E region of ionosphere.

Altitude dependence of electron number density formed by diffusion of metallic ions in horizontal DC electric field in the ionosphere over the seismic region. Dashed line corresponds to the molecular ions number density. Angle of magnetic field inclination

Altitude dependence of electron number density in the D layer of ionosphere at flowing electric current from the atmosphere. Change of electric charge carriers from negative ions to electrons in the electric current flowing through D layer result in perturbation of the ionosphere. Line (3) – Electric current is missing. Line (2) – Temperatures of electron and ion are same. Line (1) – Temperature of electrons at their heating by electric current more than temperature of ions.

Scheme of processes forming the electrodynamic model of atmosphere – ionosphere coupling Typhoons Earthquakes Eruptions Near– ground atmosphere. Convective transport of charged aerosols and external electric current formation. Atmosphere. Electric current in the atmosphere – ionosphere circuit. Ionosphere. DC electric field, AGW instability, ionosphere conductivity irregularities. Magnetosphere. Field-aligned currents, plasma density irregularities. Ground based data Changes in the ionosphere F layer. Occurrence of sporadic E s layer. ULF geomagnetic pulsations Changes in whistler characteristics. Satellite data DC electric field enhancement Plasma density irregularities ULF/ELF electromagnetic oscillations

Conclusion Convective transport of charged aerosols in the lower atmosphere at different stages of typhoon and earthquake development leads to formation of external electric current. The calculations and satellite data show that DC electric field in the ionosphere can reach the magnitudes of the order of mV/m. Increase of DC electric field stimulates the numerous electromagnetic and plasma effects. The limitation of long-term (1 to 10 days) electric field disturbances within earthquake area on the Earth surface is caused by feedback mechanism between excited electric field and the causal external current. The effect of electric field limitation on the ground creates significant advantage for satellite monitoring of seismic related electric field disturbances as compared to ground-based observations. Presented model can be used for the new methods of monitoring natural disasters and technogenic catastrophes.

We tried to find the answers on the following questions: 1. What plasma and electromagnetic processes can be connected with the enhancement of DC electric field in the ionosphere? Answer. If DC electric field exceeds some threshold value of the order of 10 mV/m then the following effects are appeared: - AGW instability and horizontal ionosphere conductivity irregularities; - The field - align electric currents and plasma density irregularities stretched along geomagnetic field lines; - Whistler duct in the ionosphere and the magnetosphere; - Electromagnetic ELF emissions in the ionosphere; - ULF geomagnetic field oscillations on the Earth surface. - Lower ionosphere disturbances and sporadic E-layer formation. - Lower ionosphere disturbances and sporadic E-layer formation. - Possibly lightning discharges appearance. 2. What physical processes lead to enhancement of DC electric field in the ionosphere? Answer. We considered one of the possible mechanisms. It is connected with the formation of additional external electric current in the global atmosphere - ionosphere current circuit due to vertical turbulent transport of the charge aerosols in the near ground level. - Possibly lightning discharges appearance. 2. What physical processes lead to enhancement of DC electric field in the ionosphere? Answer. We considered one of the possible mechanisms. It is connected with the formation of additional external electric current in the global atmosphere - ionosphere current circuit due to vertical turbulent transport of the charge aerosols in the near ground level.

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