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Downscaling of GFS single file

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Hello, I want to compare WRF output with two nested domains with input GFS data. To do so, I would like to process GFS files to obtain wrfout for every hourly input file in the desired domain (matching the case with nesting).
I was thinking about doing 1h runs every time with a different gfs file as input ubgrib data, but this results in two wrfout files (the start hour matching GFS timing and the next hour). I tried doing run_hours=0 in namelist.input but I get no output. Should I only keep only the first file for every simulation?
Is there a way to do this single downscaling of GFS files without having WRF to integrate over time?
Thanks in advance,
GFS analysis is at 6-hour interval and GFS forecast is at 3-hour interval. So it will be more reasonable if you compare WRF outputs at either 6-hour interval or 3-hour interval with GFS data.
When you run real.exe, you can set "all_ic_times = .true." (&time_control). This option will allow real.exe to output wrfinput at the time interval of incoming forcing data (e.g., 3-hour or 6-hour interval GFS forcing data). These wrfinput files can roughly represent GFS. You can then compare your wrfout with these wrfiput files at the corresponding time.
I hope this is helpful for you.
Hello Ming Cheng, thanks for your answer.
I am using GFS files at 1-hour interval for forecasting (after 120h they are given every three hours but I just want to use 96h). My intention is to use wrfout files at every run (with run_hours=1) to compare wrfout files resulting from a nested run.
I was thinking about running ungrib, metgrid and geogrid program for all times and then using a loop when running real and wrf.exe. I looked at both wrfout files that I get when running only 1 hour of simulation and found that the first one has RAINC and RAINNC set to 0 and variables such T2 or Q2 have a default value, so I assumed it would be better to use the second wrfout created, after time interpolation.