fpsn does not equal to GPP

[11438023@zju_edu_cn]

Dear all, I am working with E1850CN compset and did two experiment: (1) defualt control case;  (2) experimnt case. I did not change model code at all.In my simulation results, changes of photosynthesis (fpsn) does not equal to gross primary production (GPP).  While photosynthesis increases, GPP decreases.  For my understanding, these two variables should be the same when having the same units. I don't know why they are different here... PS, Since I included CN mode, is this because photosynthesis process is done before CN mode applying and GPP after CN mode applying?   Best,Lei  

 

[oleson]

Yes, photosynthesis is downregulated due to nitrogen limitation when CN is on.

 

[11438023@zju_edu_cn]

Thanks oleson! So can I say the difference between GPP and fpsn (GPP minus fpsn) represents the effect of Nitrogen cycle?    

 

[oleson]

I *think* you could say that, you might look at the code and technical note to make sure.