Illustration of Cowling channel coupling to the shear Alfven wave

Decomposition of horizontally extended current system into components in the polarization processes and extraction of Cowling channel defined in the companion paper embedded in the total current system are numerically demonstrated. We successfully visualize the background and polarization components in the magnetosphere-ionosphere coupling process by using the proposed theoretical framework. As a fundamental response, the polarization charge produced by the Pedersen current divergence has a role to cancel and intensify the ambient background electric field inside and outside the high-conductivity band, respectively. In contrast, the polarization charge produced by the Hall current divergence has a role to rotate the electric field from the background electric field, which causes a meandering of ionospheric convection flow along the boundary of a high-conductivity band. The Hall and Pedersen currents are always perpendicular to each other. They never close each other when conductances are homogeneous, but they can do that at the conductivity gradient region. This is the reason why a Hall polarization charge is induced and a resultant Cowling channel is formed. Key Points Illustration of Cowling channel Hall and Pedersen current close each other at the conductivity gradient region Identify the Hall polarization field and Alfven conductance