In the integration time step calculation here, the Dx, Dy, and Dz are assumed to be in metres, which are not necessarily the native units of the spatial projection (e.g., for my output using GEOS-Chem, the units here are degrees).
A 'quick fix' for those using degrees is to simply multiply the Dx, Dy, and Dz by 100,000. This may cause numerical stability problems at latitudes where 1 degree is significantly less than 100km; so a smaller multiplier would be better if these latitudes are within the spatial domain (in my case they are).
A long-term solution would have the time step equation change accordingly, taking into account the native resolution of the output, or perhaps have it be specified by the user.
In the integration time step calculation here, the Dx, Dy, and Dz are assumed to be in metres, which are not necessarily the native units of the spatial projection (e.g., for my output using GEOS-Chem, the units here are degrees).
A 'quick fix' for those using degrees is to simply multiply the Dx, Dy, and Dz by 100,000. This may cause numerical stability problems at latitudes where 1 degree is significantly less than 100km; so a smaller multiplier would be better if these latitudes are within the spatial domain (in my case they are).
A long-term solution would have the time step equation change accordingly, taking into account the native resolution of the output, or perhaps have it be specified by the user.