DISSIPATION OF NONLINEAR ALFVEN WAVES

By numerically solving the equations of magnetohydrodynamics in time a nd one spatial coordinate we show that non-linear effects lead to sign ificantly increased dissipation rates for linearly polarised Alfven wa ves of high amplitude. The increased dissipation rate is a result of t he appearance of current sheets at magnetic pressure minima during the evolution of the wave. We discuss the relevance of this mechanism for the energetics of solar and stellar coronae. The Alfven waves in the lower solar corona are of too low amplitude for this mechanism to be i mportant, but it may be operative in the solar wind as well as in the coronae of late-type giants.