Comment on “An improved coupling model for the lithosphere‐atmosphere‐ionosphere system” by Kuo et al. [2014]

Abstract

The lithosphere‐atmosphere‐ionosphere coupling problem is a challenge nowadays. It requires understanding of (a) the physical mechanism that is responsible for plasma disturbances generation at ionospheric heights, (b) the penetration of seismogenic impact from the ground into the ionosphere through the underlying neutral atmosphere, and (c) on‐the‐ground (in‐the‐ground) sources generation. Kuo et al. (2014) reported an improved model of lithosphere‐atmosphere‐ionosphere coupling that includes the ionosphere as well as the underlying neutral atmosphere (from the ground up to the ionosphere altitudes, i.e., 60–80 km above the Earth's surface). The main feature of the Kuo et al. (2014) approach is that they find ground‐to‐ionosphere currents from ∇·trueJ→=0, trueJ→≡−∇ψ system of equations. In contrast to Kuo et al. (2011), where well‐known ∇·trueJ→=0,trueJ→=trueσ̂trueE→,trueE→=−∇ϕ equations are used, Kuo et al. (2014) looks better as it does not require the knowledge of electric conductivity σ profile. In this paper we show that the Kuo et al. (2014) equations can be obtained as a special case of the Kuo et al. (2011) ones, given the electric conductivity tensor is a spatially invariant scalar. Therefore, Kuo et al. (2014) formulation may not describe correctly electric currents flowing between the Earth and the ionosphere.

Reply to comment by B. E. Prokhorov and O. V. Zolotov on “An improved coupling model for the lithosphere‐atmosphere‐ionosphere system”

“…Prokhorov and Zolotov [] pointed out the potential importance of the ∇ × J term. We find out that the neglect of the ∇ × J term does not affect the upward total currents, and the result of Ψ Method can provide a good approximation for upward currents that flow into the ionosphere obtained from the ϕ Method.…”

“…In Kuo et al [], the imposed electric field in the ionosphere is derived, via Ohm's law, from the upward/downward current in the perpendicular direction of magnetic field. Prokhorov and Zolotov [] pointed out that the choice of the ionospheric conductivity tensor will affect the derived electric field magnitude. In Kuo et al [], the ratio of the Hall conductivity to the Pedersen conductivity is estimated to be ~10, which is obtained from the website http://http:/wdc.kugi.kyoto-u.ac.jp/ioncond/sigcal/index.html.…”

“…In their comments on our 2014 article, Prokhorov and Zolotov [] pointed out that the ∇ × J = 0 approximation in equations and cannot correctly describe the currents flowing between the Earth and ionosphere.…”

Propagation of Seismogenic Electric Currents Through the Earth's Atmosphere

“…It is important to note that the solutions for the Φ and Ψ problems are valuably different, as discussed in Denisenko et al () as well as in Prokhorov and Zolotov (). However, this statement is contested in Kuo and Lee () by the analysis of one example.…”

“…The authors derived the current density j in the atmosphere using the continuity equation d i v j = 0 and showed how the atmospheric electric current j and electric field E disturbed the ionosphere above the earthquake preparation zone. Prokhorov and Zolotov () criticized the model proposed by Kuo et al () and pointed out that the formula used to derive the current j =− g r a d Ψ cannot reasonably describe the ground‐to‐ionosphere current of presumably seismic origin. Kuo and Lee () replied by considering two approaches to solve the equation d i v j = 0 .…”