The purpose of this testmod is to exercise the newer snow cover fraction method along with having use_subgrid_fluxes = .false. Note that we also need h2osfcflag = 0 in this testmod, because h2osfcflag = 1 is incompatible with use_subgrid_fluxes = .false. Also, this needs to be used in a clm45 configuration for compatibility with other options (or else would need to set some other flags: lower_boundary_condition and possibly others)