out_dt in hydro.namelist

[Sara B]

Dear WRF-Hydro users,

I would have a question regarding the temporal resolutions defined in FORCING_TIMESTEP (in namelist.hrldas) and out_dt (in hydro.namelist).

I am running WRF-Hydro forced by WRF (FORC_TYP = 3) for one day (from 2026/04/30 00:00 until 2026/04/31 00:00). 

Time frequency of forcings is one hour, i.e. FORCING_TIMESTEP = 3600 and NOAH_TIMESTEP = 3600 (seconds). Time frequency of hydrological outputs is defined in out_dt (in minutes). I wished to get outputs at a resolution higher than one hour, so I tried to set out_dt=15. However, the result was not correct...
- the time written in the names of the output files was every hour

- I obtained 24 output files instead of 24*4, as I thought

- nevertheless, the timestamp inside the output files was every 15 minutes...

For example, the time inside the last file (202603310000.CHRTOUT_DOMAIN4) was 2026-03-30 06 (ncdump -v time -t 202603310000.CHRTOUT_DOMAIN4).

I have the feeling that the outputs refer to hours (every 60 minutes), although out_dt=15.

I would like to ask you if the minimum time that can be defined in out_dt is maybe the time of FORCING_TIMESTEP and why (since the integration time of the model is of the order of seconds, I thought it was possible to save the output files at the desired temporal resolution).

Thank you very much!

Best regards,

Sara B