The GFDL AM2.0 dynamical core is based on the Held-Suarez Forcing(1994). In designing the forcing and dissipation, we use simple Newtonian relaxation of the temperature field to a zonally symmetric state and Rayleigh damping of low-level winds to represent boundary-layer friction. Forcing GCMs in this way is relatively common, especially in two-layer models [Hendon and Hartmann (1985) and Suarez and Duffy (1992) are two examples.
The first in the proposed series of benchmark calculations is described in this report
\[\frac{\partial{v}}{\partial{t}}=...-k_{v}(\sigma)v\] \[\frac{\partial{T}}{\partial{t}}=...-k_{T}(\phi,\sigma)[T-T_{eq}(\phi,p)]\] \[T_{eq}=max\{200K,[]\}\] \[k_T=...\] \[k_v=...\] \[\sigma_b=...\] \[k_f=...\]
The model is design for multi-core, but the single core is enough for T42 simulations. You need modify the mkmf.template.ifc in ./bin/ if you are using ifortran :
# mkmf -t template.ifc -c"-Duse_libMPI -Duse_netCDF" path_names /usr/local/include
FFLAGS = -stack_temps -safe_cray_ptr -ftz -i_dynamic \
-assume byterecl -O2 -i4 -r8 -w95 \
-I/opt/netcdf-3.6.3-intel/include
and the fms.script in ./exp/spectral/
$mkmf -p fms.x -t $template -c "-Duse_netCDF" -a \
$sourcedir $pathnames /usr/local/include \
$sourcedir/shared/mpp/include $sourcedir/shared/include