Model of the D-layer disturbances Model of the D-layer disturbances related to natural disasters.related to natural disasters.

Alexey I. Laptukhov, Valery M. Sorokin, Alexey I. Laptukhov, Valery M. Sorokin, and Alexey K. Yaschenko and Alexey K. Yaschenko

PUSHKOV INSTITUTE OF TERRESTRIAL MAGNETISM, IONOSPHEREPUSHKOV INSTITUTE OF TERRESTRIAL MAGNETISM, IONOSPHEREAND RADIO WAVE PROPAGATION (IZMIRAN) RUSSIAN ACADEMY OF SCIENCESAND RADIO WAVE PROPAGATION (IZMIRAN) RUSSIAN ACADEMY OF SCIENCES

The The formationformation mechanismmechanism of of ionosphere ionosphere D-layer disturbance D-layer disturbance by electric current by electric current flowing from the atmosphere to the flowing from the atmosphere to the ionosphere ionosphere was considered. was considered. Latest observations revealed Latest observations revealed such disturbance due to variations of amplitude and a phase such disturbance due to variations of amplitude and a phase of the very low-frequency (20 - 50 KHz) radio waves. These of the very low-frequency (20 - 50 KHz) radio waves. These waves were propagated in the Earth - ionosphere wave guide waves were propagated in the Earth - ionosphere wave guide near to an epicenter of preparing earthquakes. Transmitters near to an epicenter of preparing earthquakes. Transmitters and receivers of these waves were located on a surface of and receivers of these waves were located on a surface of the Earth. Similar anomalies of radio wave characteristics the Earth. Similar anomalies of radio wave characteristics were observed during few days prior to earthquake. were observed during few days prior to earthquake. ..

Observations of the VLF-LF signal anomalies Observations of the VLF-LF signal anomalies associated with earthquakesassociated with earthquakes

Enlargement of the trend of the radio-signal in the period March–May 2002. The arrow indicates the occurrence of the gulf of Taranto main earthquakes.

P.F.Biagi , R. Piccolo ,L. Castellana , et.al., Natural Hazards and Earth System Sciences (2004) 4: 685–689

Model descriptionModel description

Intensive natural and artificial disasters generate external electric Intensive natural and artificial disasters generate external electric current in the lower atmosphere due to convective transport of current in the lower atmosphere due to convective transport of charged aerosols.charged aerosols.

External electric current generates conductivity electric current in External electric current generates conductivity electric current in the Earth-ionosphere layer.the Earth-ionosphere layer.

Conductivity electric current flowing through D-layer of the Conductivity electric current flowing through D-layer of the ionosphere leads to transport of electrons and negative charged ionosphere leads to transport of electrons and negative charged ions.ions.

The electric field leads to transfer of electrons, positive and negative The electric field leads to transfer of electrons, positive and negative charged ions in D - layer of the ionosphere. In the top part of layer charged ions in D - layer of the ionosphere. In the top part of layer there are free electrons, and in its bottom part there are negative there are free electrons, and in its bottom part there are negative charged ions which occur at quickly absorption of electrons to charged ions which occur at quickly absorption of electrons to neutral molecules. The electron number density perturbation neutral molecules. The electron number density perturbation appears in the D layer of the ionosphere caused by changed of type appears in the D layer of the ionosphere caused by changed of type of carriers at current flowing through this layer.of carriers at current flowing through this layer.

The model of electric current formation in the Earth-The model of electric current formation in the Earth-ionosphere layer. ionosphere layer.

1. Earth surface.1. Earth surface.

2. Conducting layer of2. Conducting layer of

the ionosphere.the ionosphere.

3. External electric3. External electric

current in natural current in natural

disaster region.disaster region.

4. Conducting electric 4. Conducting electric

current in the current in the

atmosphere -atmosphere -

ionosphere circuit.ionosphere circuit.

5. Field – aligned5. Field – aligned

electric current.electric current.

2

3

Er

z1

4

5

B z

x

1

Sorokin, V.M., Chmyrev, V.M., Yaschenko, A.K.,

Journal of Atmospheric and Solar-Terrestrial Physics 63, pp.

1681-1691.

Basic equation set in the quasi stationary approximation Basic equation set in the quasi stationary approximation

Continuity equationsContinuity equations

Quasi neutrality conditionQuasi neutrality condition

, ,

e e r e a e d

r e i

a e d i

e e

dN v q N N N N

dzd

N v q N N N Ndzd

N v N N N Ndzv E v E v E

eN N N

Electric current conservationElectric current conservation

jj00 is the electric current density flowing to the ionosphere from the zone is the electric current density flowing to the ionosphere from the zone

of natural disasterof natural disaster

Heating equationHeating equation

0( )e e ij e N N N E j const

2

3n

eB e en

m eET T

k m

Simplified equation setSimplified equation set

2

22

2 2

0

1/ 2

( )1;

1 1 1

11

3

/ /

/ / (1 2 )

r ie

n

B

e

a d e

N N NdJ q N N

dz

Jm

k T N

J j e const const

T T

Calculation result of the altitude dependence of electron number Calculation result of the altitude dependence of electron number density at different value of electric current.density at different value of electric current.

30

40

50

60

-1 0 1 2 3

jn = 2 10-12 A / m2

j / jn= -104

j / jn=200

lg(Ne [sm-3])

z , km

undisturbed

j / jn= -2 103

Calculation result of the altitude dependence of positive ion number Calculation result of the altitude dependence of positive ion number

density at different value of electric current.density at different value of electric current.

40

50

60

2,5 3,0 3,5 4,0

z , km

lg(Ni [cm-3])

jn = 2 10-12 A / m2

j / jn=200

j / jn= -104

j / jn= -2 103

undisturbed

Calculation result of the altitude dependence of electric field at different Calculation result of the altitude dependence of electric field at different

value of electric current.value of electric current.

30

40

50

60

-4 -2 0 2 4lg(E [V / m])

z , km

j / jn=200

j / jn= -104

j / jn= -2 103

jn = 2 10-12 A / m2

Calculation result of the altitude dependence of electron number Calculation result of the altitude dependence of electron number density performed with taking into account electron heating by electric density performed with taking into account electron heating by electric

field.field.

30

40

50

60

-2 0 2

321

1 - Ne0

2 - Te=T

3 - Te>T

z, km

lg(Ne[cm-3])

Two-dimensional spatial distributions of electron number Two-dimensional spatial distributions of electron number densitydensity

ConclusionConclusion

Calculation of Calculation of the disturbances of the disturbances of electron electron number number density density in the in the D-D-layer layer of ionosphere has been of ionosphere has been carried outcarried out. These disturbances . These disturbances caused by changing type of charge carriers at their transport in the caused by changing type of charge carriers at their transport in the atmosphere electric current flowing upward to the ionosphere. atmosphere electric current flowing upward to the ionosphere. EEeffect of Joule heating effect of Joule heating ofof electron electrons by electric field to the s by electric field to the disturbadisturbances formation has been analyzed. nces formation has been analyzed. Result of calculations Result of calculations showshowss that growth of external electric current density by 3 that growth of external electric current density by 3-4-4 orders orders of magnitude leadof magnitude leadss to to occurrence of the occurrence of the disturbance of electron disturbance of electron density density up to one up to one order, reaching its maximum at heights of order, reaching its maximum at heights of 440-60 0-60 kmkm. . ThThisis model model can be applied to the interpretation of observation can be applied to the interpretation of observation data of the lower ionosphere perturbations over seismic regions anddata of the lower ionosphere perturbations over seismic regions and other natural and technogenic catastrophesother natural and technogenic catastrophes related to formation of related to formation of electric current in the atmosphereelectric current in the atmosphere. .