AN INITIAL-VALUE PROBLEM FOR MAGNETOATMOSPHERIC WAVES .1. THEORY

The initial value problem is solved for the pressure field resulting from an instantaneous localized forcing term in a horizontally-stratified isothermal compressible atmosphere, with a uniform gravitational field and a non-uniform horizontal magnetic field. The waves generated in this system are termed magnetoatmospheric waves. Exact integral expressions are given for the high and low frequency pressure fields emanating from the source, for motion varying in the plane containing the gravitational field and magnetic field vectors, and also orthogonal to this plane. In each case, the presence of a lower rigid boundary (z = 0) gives rise to a horizontally propagating Lamb-type surface wave. Particular emphasis is put on the nature of the singularities in the complex frequency plane and their physical representations. © 1990.