On viscous and resistive dissipation on Alfvén waves in an isothermal atmosphere (Q1365296)

The author considers an isothermal atmosphere permeated by a uniform vertical magnetic field. The gas is assumed to be viscous and resistive, so the dissipation effects can be taken into account. The study shows that for an Alfvén wave coming from the vertical direction, the atmosphere may be divided into two distinct regions connected by an absorbing and reflecting transition layer. In the transition layer the dissipation and absorption of the magnetic energy of the incident wave take place, and the kinematic viscosity changes from small to large values. In the lower region, the effects of resistive diffusivity and kinematic viscosity on the wave are negligible. Here the wave field can be described as a linear combination of two waves, an incident one and a reflected one, with different wavelengths and dissipative factors. In the upper half-space, the effects of resistive diffusivity and the kinematic viscosity are significant; however, the incident wave should behave like a constant, if it corresponds to the boundary conditions. The model and the conclusions offer interesting applications to the problem of solar heating.