A disturbance in the exosphere generates waves in three partially separable modes. These modes are described by considering the vorticity about a line of force,

A disturbance in the exosphere generates waves in three partially separable modes. These modes are described by considering the vorticity about a line of force,

Here is a fascinating text that integrates topics pertaining to all scales of the MHD-waves, emphasizing the linkages between the ULF-waves below the ionosphere