There should be only one reference density that is a conversion factor from mass to pseudo-thickness \tilde{h}.
The VertCoord module uses Rho0 from the config file (here)
while the wind forcing tendency uses the RhoSw from the GlobalConstants.h

Have we agreed on where to store the official conversion factor?
I think GlobalConstants.h makes it easy to set other factors such as SFluxFac or HFluxFac. Are there use cases for which we need it to remain user-defined?