  We have used high-speed spectroscopy of the rapidly oscillating Ap (roAp)
star HD99563 to study the pulsation amplitude and phase behaviour of elements
in its stratified atmosphere over one 2.91-d rotation cycle. We identify
spectral features related to patches in the surface distribution of chemical
elements and study the pulsation amplitudes and phases as the patches move
across the stellar disk. The variations are consistent with a distorted
nonradial dipole pulsation mode. We measure a 1.6 km/s rotational variation in
the mean radial velocities of H-alpha and argue that this is the first
observation of H-alpha abundance spots caused by He settling through
suppression of convection by the magnetic field on an oblique rotator, in
support of a prime theory for the excitation mechanism of roAp star pulsation.
We demonstrate that HD99563 is the second roAp star to show aspect dependence
of blue-to-red running wave line profile variations in Nd iii spots.
