Stability Diagnostics


I have a question about the stability diagnostics (e.g., CFL conditions) for a non-hydrostatic simulation. After turning on the DIAG_CFL flag, the screen display shows a few CFL conditions that are specific to the non-hydrostatic mode, which are: NBQ_HADV, NBQ_IMP, and NBQ_VSOUND. According to the tutorial, NBQ_HADV is the CFL condition associated with the horizontal pseudo-phase-speed of acoustic waves. I presume the other two CFL conditions are associated with the vertical pseudo-phase-speed of acoustic waves. Can someone explain what those two CFL conditions are and the difference between them? Also, what are the typical upper bounds of those CFL conditions?

Many thanks!