Brian Kauffman, Oct 2005

tn460nyf refers to the ocean model "normal year" forcing data described in
NCAR Technical Note TN-460, 2004, by W.G. Large and S.G. Yeager


For general use, these files should be used
   tn460nyf.correction_factors.T62.050923.nc
   tn460nyf.ncep.T62.050923.nc
   tn460nyf.giss.T62.051007.nc
   tn460nyf.gxgxs.T62.051007.nc

For purposes of validating datm7 code wrt to latm6 from ccsm3_0_rel04
(to which NCAR/oce mods are applied so that latm6 uses tn460 nyf data),
these files should be used:

   tn460nyf.correction_factors.T62.050923.nc
   tn460nyf.ncep.T62.050923.nc
   tn460nyf.giss.T62.050923.nc  [a]
   tn460nyf.gxgxs.T62.050923.nc [b]

   the validation run data differences relative a general use run involve
   tweaks to the time axis of the data:
   [a] giss radiation data is assigned to midnight of each day (instead of noon)
   [b] gxgxs precip data is assigned to Jan 15 and the 14th of every other month
      (instead of the 15th of every month)

   Note: in addition to input data file mods, source code mods are also
   necessary for such a validation run (they recreate bugs in latm6).
   1) on an initial run only, the model must start from year=1, but the 
      0001-Jan-01 0s sample of ncep data must be assigned to
      0000-Jan-01 0s (ie. one year too early)
   2) the correction to NCEP Arctic potential temperature must not be
      done in the northern-hemisphere (y > 60n)