If your input data does not have any surface information (e.g., 2m T, 10m U, V, etc.), you can simply edit WPS/metgrid/METGRID.TBL by adding a line as follows for TT, QV, UU, and VV:
fill_lev = 200100:TT(X)
where X will be the number of the lowest model level in your input data. For example, you can set:
fill_lev = 200100:TT(100000)
This says that 1000mb temperature is filled-in as surface temperature. In the REAL program, you should then set use_surface = .false.
fill_lev = 200100:TT(X)
where X will be the number of the lowest model level in your input data. For example, you can set:
fill_lev = 200100:TT(100000)
This says that 1000mb temperature is filled-in as surface temperature. In the REAL program, you should then set use_surface = .false.