!-----------------------------------------------------------------------
!  grid information 
!-----------------------------------------------------------------------
   cn_src_hgr = 'some_dir/mesh_hgr_src.nc'
   cn_src_zgr = 'some_dir/mesh_zgr_src.nc'
   cn_dst_hgr = 'some_dir/mesh_hgr_dst.nc'
   cn_dst_zgr = 'some_dir/mesh_zgr_dst.nc'
   cn_src_msk = 'some_dir/mask_src.nc'