Magnetoacoustic surface waves in the solar atmosphere

The nature of magnetoacoustic surface waves at a single magnetic interface is examined for the case of parallel propagation. Above the interface is an isothermal medium permeated by a uniform horizontal magnetic field. The lower region is a field-free medium of different temperature to the magnetic atmosphere. In the absence of gravity the interface may support one or two surface modes determined by the temperatures of the two media. The effect of gravity on the modes is examined. A possible application of the fast magnetoacoustic surface mode is to the running penumbral wave. (author) 17 refs. 3 figs