spost (simple post)

Spost is used by CORe to create the pressure level analyses for the
ensemble members by using a log(P) interpolation.  

The code used by CORe can also also output sigma level analyses.  Earlier 
versions were able to produce height above MSL.  One should be able
to alter the code to produce analyses on isentropic surfaces.

The code just does a vertical interpolation of fields that are already
present in the input file.  


Input: grib2 fields on model surfaces
       grib2 template

Output: grib2 fields on selected levels

Restrictions: points that are underground have undefined values.
              OpenMPI: no
              OpenMP: yes
              external libraries: libwgrib2

              U/V interpolation: simply does a vertical interpolation of U/V.
               In theory, U/V is the U/V on a constant hybrid sigma-pressure surface.
               Should find the 3-D wind, vertically interpolate and then find the U/V
               that is parallel to a constant height surface.