Directory structure:

fortran mode source code and Makefile in src directory.
python interface to spectral data files and sample plotting scripts in python directory.
model executable (gfs) put in bin directory by Makefile.
heldsuarez_test holds test data and scripts for Held-Suarez dycore test.

Prerequistes:  

a fortran compiler (tested with intel fortran and gnu fortran)
fftw3 FFT library (fftw.org)
*blazingly fast* shtns spherical harmonic lib (https://bitbucket.org/nschaeff/shtns/wiki/Home)

To build:

cd src
ln -fs Makefile.conf.gfortran Makfile.conf  # if you're using gfortran
ln -fs Makfile.conf.ifort Makefile.conf # if you're using ifort

you may need to edit Makefile.conf to adjust compiler options and/or
library paths.

for full gfs model, run
  make clean (clean and setup symlinks)
  make w3lib (build ncep w3lib)
  make libgfs (build library containing gfs physics routines)
  make gfs (executable is bin/gfs)

for Held-Suarez test, run
  make clean-hstest (clean and setup symlinks)
  make w3lib (build ncep w3lib)
  make libgfs (build library containing gfs physics routines)
  make (executable is bin/gfs)

for DCMIP test cases 4 and 5 (http://earthsystemcog.org/projects/dcmip-2012/), run
  make clean-dcmip (clean and setup symlinks)
  make w3lib (build ncep w3lib)
  make libgfs (build library containing gfs physics routines)
  make (executable is bin/gfs)

To test:

to run held-suarez test case, cd to heldsuarez_test directory and run test_gfs.
plot zonal mean zonal wind and temperature using python/plotzonalmean.py
compare resulting plots to zonalmeanu.png and zonalmeant.png.

to run a DCMIP test case, cd to dcmip_test and run test_gfs.
plot surface pressure using python/plot_test4.py and compare resulting plot with ps410.png
and plots for other models on DCMIP page (http://earthsystemcog.org/projects/dcmip-2012).

Contact:  Jeff Whitaker <jeffrey.s.whitaker@noaa.gov>