GRAINC_TO_FOOD

[Chr]

Hello CLM experts,

I have a question about converting GRAINC_TO_FOOD to grain yield. The CLM5 technote states:

"Calcuating the crop yields (Equation (26.9)) requires that you sum the GRAINC_TO_FOOD variable for each year".

This sounds straight forward, yet, I have trouble applying Eq. 26.9. GRAINC_TO_FOOD is in gC m-2 s-1 and Grain yield is in gC m-2. Does it mean that

(1) I have to apply a factor of 60s x 60min x 24h for an daily output (hist_mfilt=365, hist_nhtfrq=-24), then sum the variable for the entire year. OR
(2) I have to apply a factor of 60s x 60min x 24h x 365 d for an annual output (hist_mfilt=1, hist_nhtfrq=-8760) ?

Also, which output metric should I use: Average, Instantaneous, Minimum, Maximum?

Thanks for your help.

 

[dll@ucar_edu]

Hi Christian,

I typically look at GRAINC_TO_FOOD averaged in the monthly files (the default CLM output) and multiply the variable by 60sec/min * 60min/hr * 24hr/day * no. days per month.

Part of the reason we recommend using the summed GRAINC_TO_FOOD variable is because the grain pool (GRAINC) is harvested in a single time step and is 0 after harvest, leading to averaging 0 values for any given monthly average. You should be able to pull the maximum value of GRAINC from the daily output (per crop for each year) with similar results.

Danica