Lou Chuang Lee

Report
Seismology Forum Meeting 2014:
Recent Advances and New Findings in Seismology
An Electric Coupling Model for the
Lithosphere-Atmosphere-Ionosphere System
L. C. Lee
Institute of Earth Sciences, Academia Sinica
March 19, 2014
1
Lithosphere – atmosphere – ionosphere coupling
Kuo, Huba, Joyce and Lee, JGR (2011, 2013)
Ionosphere density variations
Variations of fmF2 and TEC before Chi-Chi EQ
EQ
[Liu et al., 2001]
2
3
J ≃ 100 nA/m2
4
Current Dynamo from Stressed Rock
5
Model of DC electric field generation in the ionosphere by seismic related EMF
(electro-motive force) in the lower atmosphere. 1. Earth surface, 2. Conductive layer of
the ionosphere, 3. External electric current of EMF in the surface atmosphere, 4.
Conductivity electric current in the atmosphere–ionosphere circuit, 5. DC electric field
in the ionosphere, 6. Field-aligned electric current, and 7. Charged aerosols injected into
the atmosphere by soil gases (Sorokin and Hayakawa, 2013).
6
Thunderstorm effect on the ionosphere
 ≃ 250kV
Fair weather
current
J1
J2
=
JD
7
Conductivity profile
[Tzur and Roble, 1985]
8
Lithosphere Dynamo
9
The E field, current density J and induced
charge density  in the atmosphere
 ≡ −Ψ = 
(1)
 = −ϕ
(2)
 ⋅  =  /
(3)
 ⋅  =  ⋅  ⋅  = − ⋅  ⋅ ϕ = 
(4)
2
or  ⋅  = − Ψ= 0
(5)
10
Current density and discharge rate
11
Induced charge density
12
For a scalar conductivity
 ⋅  =  ⋅ σ = 
σ ⋅  + σ ⋅  = 

 =   ⋅  = −  ⋅

J = σ1 E1 = σ2 E2
σ1 < σ2
σ2
E2
----
σ1
E1
E1 > E2
13
Induced charge density
ocean
14
Electric coupling of lithosphere,
atmosphere and ionosphere
Kuo, Huba, Joyce
and Lee, (JGR, 2011)
15
Current density and flow in the atmosphere
16
17
18
NRL 3D ionosphere simulation code
(SAMI3)
• SAMI3 is a 3D low-latitude ionospheric model developed
at the Naval Research Lab
• SAMI3 simulates the temporal and spatial evolution of
seven ion species (H+,He+,N+,O+,N2+,NO2+,O2+) over the
entire magnetic flux tube in both hemispheres
• The density and velocity equations are solved for all ion
species.
• Ion temperature equation and electron temperature
equations
• The altitude range is ±30° and the longitude range is 8°
for our case
• The range of magnetic apex height is 85 to 2400 km
19
Modified potential equation in SAMI3
(1)
(2) Use Dipolar Coordinates
(dipole magnetic field lines)
20
21
22
23
24
25
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Summary
•
•
•
•
The magnitude of current density Jrock is the most
important parameter to determine the TEC variations
and nighttime bubble formation in the ionosphere.
The current density Jrock = 10 - 100 nA/m2 in the
earthquake fault zone can cause TEC variations of up
to 2 – 20 % in daytime ionosphere.
A current density Jrock = 1 - 10 nA/m2 can lead to
nighttime TEC variations of 2 - 20 % as well as the
formation of nighttime plasma bubble (equatorial spread
F) extending over the whole magnetic flux tube
containing the earthquake epicenter.
Daytime and nighttime TEC variations and nighttime
plasma bubbles within the affected region can be used
as precursors for earthquake prediction.
27
Thank You
中央研究院 地球科學所
Institute of Earth Sciences, Academia Sinica
Taipei, Taiwan
28

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