An improved coupling model for the lithosphere‐atmosphere‐ionosphere system

Abstract

In our previous model for the lithosphere-atmosphere-ionosphere coupling, the background magnetic field was assumed to be perpendicular to the horizontal plane. In the present paper, we improve the calculation of currents in the atmosphere by solving the current density J directly from the current continuity equation ∇ • J = 0. The currents in the atmosphere can be solved for any arbitrary angle of magnetic field, i.e., any magnetic latitude. In addition, a large ratio (~10) of Hall to Pedersen conductivities is used to generate a large Hall electric field. The effects of atmospheric currents and electric fields on the ionosphere with lithosphere current source located at magnetic latitudes of 7.5°, 15°, 22.5°, and 30°are obtained. For upward (downward) atmospheric currents flowing into the ionosphere, the simulation results show that the westward (eastward) electric fields dominate. At magnetic latitude of 7.5°or 15°, the upward (downward) current causes the increase (decrease) of total electron content (TEC) near the source region, while the upward (downward) current causes the decrease (increase) of TEC at magnetic latitude of 22.5°or 30°. The dynamo current density required to generate the same amount of TEC variation in the improved model is found to be smaller by a factor of 30 as compared to that obtained in our earlier paper. We also calculate the ionosphere dynamics with imposed zonal westward and eastward electric field based on SAMI3 code. It is found that the eastward (westward) electric field may trigger one (two) plasma bubble(s) in the nighttime ionosphere.

Ionospheric influence on the seismo-telluric current related to electromagnetic signals observed before the Wenchuan <i>M</i><sub><i>S</i></sub> 8.0 earthquake

“…When we investigate electromagnetic emissions induced by an electrical current or a magnetic moment on the surface or beneath the Earth, the effect of the medium air, crustal as well as ionosphere should be taken into account since these three media consist of different conductivities and we need to consider a lithosphereatmosphere-ionosphere electromagnetic coupling (Cummer, 2000). Several tentative LAIC models have been constructed based on ground-based and ionospheric observations prior to strong earthquakes and the investigation of the influence of external electrical field on ionospheric parameters has been developed quickly (Pulinets and Ouzounov, 2011;Pulinets and Davidenko, 2014;Hayakawa, 2013, 2014;Kuo et al, 2011Kuo et al, , 2014Zolotov et al, 2012;Zolotov, 2015). At the same time, the ionosphere plays an important role in electromagnetic propagation at ELF and very low frequency (VLF).…”

Preseismic TEC Changes for Tohoku-Oki Earthquake: Comparisons Between Simulations and Observations

“…The direction of dynamo current flowing in the atmosphere depends on the sign of the generated charges over the Earth's surface near the stressed rock region: downward to (upward from) negative (positive) surface charge regions. Kuo et al (2014) improved the LIA system coupling model over the previous model (Kuo et al 2011) which is valid only for magnetic latitude 90° and underestimates the imposed electric field at the lower ionosphere boundary. In the new model currents in the atmosphere are calculated by directly solving the current continuity equation, 0…”

“…The TEC variation finding over the earthquake epicenter lacks physical mechanisms to explain these pre-earthquake ionospheric signatures. Kuo et al (2011Kuo et al ( , 2014 proposed an electric coupling model for the lithosphere-atmosphere-ionosphere (LAI) current system, as illustrated in Fig. 1.…”

“…The current flowing out of the ionosphere will reduce the positive charges in the ionosphere which have a higher electric potential. The currents flowing in the atmosphere are obtained by directly solving the current continuity equation J 0 $ d = (Kuo et al 2014). The current obtained in the atmosphere can be used to calculate the electric fields at the lower boundary of the ionosphere.…”

Is there any difference in local time variation in ionospheric F2-layer disturbances between earthquake-induced and Q-disturbance events?

“…On the other hand, although an improved coupling model for lithosphere-atmosphere-ionosphere coupling was developed by several authors (Sorokin and Hayakawa, 2013;Kuo et al, 2014), the mechanism of the seismo-ionospheric precursor is far from being well understood. There is a tendency of transition from acoustically-driven mechanisms to electric-field coupling (Pulinets and Davidenko, 2014).…”