External Gravity Wave Propagation on
Regular Latitude-Longitude Grid
I've supplied the above animation as an
MPEG for those who have trouble with the
above applet.
The above animation shows the surface pressure evolution after
a "splash" on the equator. The calculation is non-rotating allowing the
signal to propagate in all directions uniformly around the globe. It
takes 36 hours for a wave front to circumnavigate the entire globe.
This calculation was made simply as a sanity check for the cubed sphere experiment which compares
very favourably.
The above solution is stable because of the implicit-in-time
formulation of the surface pressure equation. Had we used an explicit
time-stepping method the convergence of meridians at the poles would
have led to a restrictive CFL limit on time-step.