Atmospheric drydeposition at the surface depends on certain surface
properties including soil and land use properties.  In most cases
these calculations can be handled in the land model and passed to he
atmosphere through the coupler.  This is the default namelist setting
drydep_method='xactive_lnd'.  However with modal areosols this method
is not adequate and we must recalculate these fields in the atmosphere
(see subroutine interp_map in mo_drydep.F90).  For unstructured grids
it was determined to create this offline interpolation tool rather
than generalize the subroutine interp_map.  

1. Locate or create scrip mapping files for the 1x1 degree input grids and
   the desired model output grid.

2. Run the script scrip_makemaps.csh 
https://svn-ccsm-models.cgd.ucar.edu/tools/mapping/makemaps/trunk/scrip_makemaps.csh
   The script will create 4 mapping files, you need only the 1x1 -> model grid 
   area average file.

3. Edit mkatmsrffile.rc and put the name of this file in the srf2atmFmapname field, edit
   other fields as appropriate

4. Set the environment variable CASEROOT to a valid cesm case directory.  This case
   has to have been compiled on the system you will run mkatmsrffile

5. Compile and run mkatmsrffile.