The electric coupling between the lithosphere and the ionosphere is examined. The electric field is considered as a timevarying irregular vertical Coulomb field presumably produced on the Earth’s surface before an earthquake within its epicentral zone by some micro-processes in the lithosphere. It is shown that the Fourier component of this electric field with a frequency of 500 Hz and a horizontal scale-size of 100 km produces in the nighttime ionosphere of high and middle latitudes a transverse electric field with a magnitude of ~20 mV/m if the peak value of the amplitude of this Fourier component is just 30 V/m. The time-varying vertical Coulomb field with a frequency of 500 Hz penetrates from the ground into the ionosphere by a factor of ~7×105 more efficient than a time independent vertical electrostatic field of the same scale size. The transverse electric field with amplitude of 20 mV/m will cause perturbations in the nighttime F region electron density through heating the F region plasma resulting in a reduction of the downward plasma flux from the protonosphere and an excitation of acoustic gravity waves.

1. INTRODUCTION
 2. BASIC ASSUMPTIONS AND EQUATIONS
 3. RESULTS AND DISCUSSION
 4. CONCLUSION
 ACKNOWLEDGMENTS
 REFERENCES

• Vitaly P. Kim(Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, Russian Academy of Sciences (IZMIRAN))
• Valery V. Hegai(Pushkov Institute of Terrestrial Magnetism, Ionosphere and Radiowave Propagation, Russian Academy of Sciences (IZMIRAN)) Corresponding Author
• Jann Yenq Liu(Institute of Space Science, National Central University)
• Kwangsun Ryu(Satellite Technology Research Center, Korea Advanced Institute of Science and Technology)
• Jong-Kyun Chung(Korea Astronomy & Space Science Institute)