Why are FDS and FDSC constantly zero?

[JanWohland]

Hi community,

we are using CESM2.1.2 and CAM6 to produce 3 hourly output. Everything looks reasonable except Shortwave downward flux FDS and Shortwave clear-sky downward flux FDSC which are both zero at all timesteps and all locations.

I am very new to the model but the run was started by someone who knows what they are doing.

Could it be that FDS and FDSC are simply not available on 3 hourly resolution? I only just realized that there are separate surface variables FSDS and FSDSC. In the end, I only need surface variables, so I will change to the latter two variables. I would guess, however, that FSDS is simply the lowest model level in FDS, such that the problem will persist.

We output both the accumulated and the instantaneous values (for a reason). Could it be that the instantaneous fluxes cause some numerical issue in the code?

I am thankful for any hint!
Jan

 

[islas]

Is it just the instantaneous fluxes that are zero? I think the radiation scheme is only called every second timestep so if the three hourly instantaneous times that you are outputting are on the time steps when it's not being called, that could be why. I don't know why it would happen for averages though. I think you'll have to output the instantaneous and average fields to different history files. If this isn't helpful, hopefully someone else knows what's going on.

Isla

 

[JanWohland]

Thanks, Isla. Good to know that the radiation scheme is only called every second timestep. Will check whether the chosen time step (I *think* hourly) and the 3h output window conflict.

Both instantaenous and accumulated FDS and FDSC are constantly zero. They were output to different history files.

Jan

 

[islas]

Hmm, ok. In that case I'm not sure my suggestion is going to be much use as I don't think that should affect the 3 hourly accumulated fields. Hopefully someone else has a better idea.

Isla