Theory Ionospheric dynamo region

figure 2. blockdiagram illustrating coupling between horizontal wind u , pressure p via ampere force jx bo, , lorentz force ux bo. here j electric current density, bo geomagnetic field, h equivalent depth, σ electric conductivity, , e electric polarization field. in self-consistent treatment of coupled system, gate b must closed. in conventional dynamo theories, gate b open.

in order determine quantitatively dynamo action of neutral wind u, 1 starts horizontal momentum equation of wind equation divergence of wind. momentum equation balances inertial force, coriolis force, , horizontal gradient of pressure p. in addition, ampere force jx bo couples electric current density j wind , pressure system. equivalent depth h (the eigenvalue of tidal mode) determines divergence of wind. electric current must obey ohm s law. electric polarization field e generated charge separation enforce condition of no sources , sinks of current. feedback between wind , electric current occurs via lorentz force ux b. usually, electric conductivity tensor σ considered given data set, , height integrated conductivity tensor Σ , height integrated sheet current j applied.

in conventional models, ampere force neglected. means gate b in figure 2 open. called kinematic dynamo. models closed gate b called hydromagnetic dynamos. influence of mutual coupling between wind , current can seen if 1 considers infinitely large electric conductivity σ. in kinematic model, electric current become infinitely large, while wind amplitude remains constant. in hydromagnetic model, current reaches upper limit, similar technical dynamo during short circuit, while wind amplitude breaks down fraction of original value. charge separation acts self-impedance preventing current become infinitely large.