| Lithosphere - Atmosphere - Ionosphere Electric Field Coupling (LAI electric field penetration) is an important part in seismic ionosphere coupling mechanism, and is also a part of global electric circuits. In recent years, several models have been developed, while the results of these models are quite different. In order to identify these models, it is necessary to establish the correct model and clear the LAI electric field Coupling mechanism.We establish two kinds of theoretical models in this thesis. The first model is used to directly solve the equation of LAIC electric field penetration, since all LAIC models belong to the first model. The equation of LAI electric field coupling can be solved only when magnetic dip angle I equals 900. So existing models are only suitable to high geomagnetic latitude. The second model is theoretical model for ionospheric electric field. Based on the analysis of LAI electric field penetration of the first kind of model, this model is tried to use ionosphere electric field model to couple with the LAI electric field penetration. Thus The LAI electric field equation can indirectly be solved in mid-low-latitude, and we will use this kind of model to analyze the ionosphere parameter effect. Specific work and results are as follows:1 In this paper, a brief overview of three hypothesis Lithosphere- Atmosphere-Ionosphere-Coupling Electric Field Source model is presented. Two models are based on an increased radon emission in earthquake preparation region, and the other is based on solid physic:activation of highly mobile electronic charge carriers named p-hole in rocks that are subjected to ever increasing levels of stress. They flow out of the stressed rock in to the unstressed rock volume, and travel to rock-air interface. All these hypothesis models propose field-ionization of air molecules, which will increase charge particles in near-surface atmosphere, and the air electric conductivity. These charged particles will change electric field and current at the bottom of atmosphere, and will result in ionosphere disturbance.2 To construct the equations of LAI electric penetration, we apply solving roots and numerical spectral to solve the equations and try to analyze LAI electric penetration by electric. The conclusions obtained are as follows.(a)The abnormal electric field in ionosphere is generated by atmosphere-ionosphere conductive currents, which is called LAI electric field penetration.(b) In the neutral atmosphere, the electrical conductivity above is higher than horizontal direction. When the source of the atmospheric electric field is large, the currents generated by the electric field at surface atmosphere flow into ionosphere completely.(c) At high latitude, ionosphere electric field is mainly horizontal, and does not change with height variation. LAI electric field penetration is much stronger at night-time than during the day.(d) the conuctivity variation at the ionosphere has little effect on the neutral atmosphere electric field.(e)The upper height has effect on electric field penetration by height-integrated Pedersen. Hence, it is related with LAI electric penetration. From analysis, it is more suitable for ionosphere upper boundary being the upper height. Under upper boundary, the currents can cross magnetic line, while it is controlled by the magnetic line. Therefore, we can assume curres moves under ionosphere upper boundary at high latitude. On the other hand, the magnetic conjugates should be considered at low latitude.(f)Model calculated that under ordinary circumstances electric field penetration efficiency is pretty low. 1V/m electric field in surface only can produce 4.70 ×10-9V/m electric field in ionosphere at night.(3) To explore the possible mechanism of earthquake precursors, we assume a significant increase in surface atmospheric conductivity. Under the condition, we can calculate the LAI electric penetration efficiency. When the surface atmospheric conductivity increase 500 times or 1000 times, the 1000V/m atmospheric electric field in surface can produce 1.9mV/m or 3.5mV/m ionosphere electric field which are 400 times or 740 times compared to means penetration efficiency. Studies have showed that the electric field penetration efficiency is positive correlation conductivity in the electric field source. This paper also calculated the external current disturbance the ionosphere electric field. Seismic activity is accompanied by emanation of soil gases into the atmosphere, these gases transfer positive and negative charged aerosols. Atmospheric convection of charged aerosols forms external electric current, which works as a source of perturbation in the atmosphere-ionosphere conductivity currents. It is shown that if the atmosphere positive ion current density is 3.20×10-6A/m2(Sorokin et al.,2005), the ionosphere electric field reaches up to 10mV/m.(4) Based on the above analyzed, we developed theoretical model of ionosphere electric fields to explore LAI electric field penetration problem. In this paper, we developed two kinds of ionospheric electric field models depending on the different assumptions, shell model and three-dimensional model.i) We developed a theoretical model for ionospheric electric fields slove LAIC electric field penetration equations. The model results are generally consistent with directly model. It had proved the validity of the mode for ionosphereic electric fields.ii) We developed shell model and 3D ionospheric electric field theory model explore mid-low-latitude LAI electric field penetration, when in the middle and low latitudes, the low magnetic latitudes, the lower LAI electric field penetration efficiency, and the electric field form become east-west dipole. The reasons are as follows:(a)height-integral Peterson conductivity will increase with latitude magnetic decreased; (b) magnetic inclination effects; (c) count the conjugate ionosphere effect; (d) the geometrical changes of the magnetic channel.iii) Three-dimensional ionospheric electric field model is used to analyze LAI electric field penetration. It shows that:(a)in the middle and low latitudes, the electric field produced by LAI penetration is more than horizontal component and vertical component;(b) the lower magnetic latitudes, the lower the height of Ionospheric electric field distribution.(c) Ionospheri electric field is bound to the magnetic lines, mapped throught the magnetic equator to the conjugate ionosphere.The Field strength is the largest in local area and the lowest in magnetic equator. The formula of electric field mapping is given in this paper.iV) In considering inhomogeneous anisotropic conductivity, the ionospheric electric field becomes inhomogeneous because of the electric current flow property. The max electric field strength of field increases 5%-25%, located at the low side of the electrical conductivity(night side), but the electric field contour profile is tilted at the high side of the electrical conductivity(day side). Then we investigate the ionosphere parameters effect in the LAI electric field penetration by ionospheric electric field equation. This study show:Pedersen conductivity and magnetic inclination angle play a decisive role, and the directional derivative of Pedersen and Hall conductivity play a less role in LAI electric field penetration.And because there are huge differences between day and night ionospheric conductivity, the LAI electric field penetration is much better at night-time than during the day. The best time efficiency is located at local time 0:00-4:00.V) When the upward currents distribution form as (4.3-2c), and its peak value is 4×10-11A/m, this current generates the ionospheric horizontal electric field values 2.0×10-6V/m,1.3×10-6V/m,1.1×10-6V/m,4.42×10-7V/m in magnetic latitudes 600,450,300,150espectively. This value is lower 4.70 x 10-6V/m in the high latitude, and is also well lower then the background values. But in the earthquake preparation, the mechanism of P-hole may ionization surface atmosphere,so that the electrical conductivity increases rapidly and vertical surface electric field can drive huge currents,.if the upward current density is 50 nA/m2, which can generates the ionospheric anomaly field strength2.5mV/m,1.6mV/m,1.37mV/m,0.56mV/m in magnetic latitudes600,450,300,150 respectively. Enough to cause the interference of the electric field in the ionosphere of middle and low latitude.(5) Based on direct and indirect models developed in this dissertation, We compared and analyzed several previous models of LAI electric field penetration. The study shows that there are several problems in these previous models, such as upper boundary setting, dimension loss and abandoning Ohm's law. |
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