Questions about BGC spinup

[Houhhu]

Hi Olsen！Sorry for late resopne. According to you suggestions, I set "reseed_dead_plants" = .true. in user_nl_clm, running an AD simulation with an initial file(clmi.I2000Clm50BgcCrop.2011-01-01.1.9x2.5_gx1v7_gl4_simyr2000_c190312.nc). The results seems betther than before. Most of area have vegetation now. Then, I increased the global thresholds several times, because my study region area is much smaller than global area. It shows the spinup is in equilibrium after running the ncl script. But I still have a few questions.
After reaching a equilibrium in a AD simulation, Should I continue the p AD spinup using the r file as initial data? In the User's Guide of BGC spinup, the Figure 1.5.5 shows spinup behavior for an 1850 pAD BGC case, does it means that spinup from an initial file only requires spinup once instear of AD spinup and p AD spinup?

 

[oleson]

Yes, start a pAD spinup using the r file from the end of the AD simulation (set "finidat" in your user_nl_clm to that file). That figure refers to an alternate method of spinning up (starting from an existing initial file in pAD mode). However, later in the user's guide, there is this caution: "If you use the default initial file and you significantly change model behavior or atmospheric forcing, and you are concerned about the carbon equilibrium (e.g., TOTECOSYSC, TOTSOMC, TOTVEGC), particularly at high latitudes, then we recommend you put the model back into AD mode to reach a new equilibrium. In this configuration, this will also automatically reseed “dead” plant functional types in the initial file with a bit of leaf carbon to give those plant functional types another chance to grow under the new atmospheric forcing or model conditions."

 

[Houhhu]

Yes, start a pAD spinup using the r file from the end of the AD simulation (set "finidat" in your user_nl_clm to that file). That figure refers to an alternate method of spinning up (starting from an existing initial file in pAD mode). However, later in the user's guide, there is this caution: "If you use the default initial file and you significantly change model behavior or atmospheric forcing, and you are concerned about the carbon equilibrium (e.g., TOTECOSYSC, TOTSOMC, TOTVEGC), particularly at high latitudes, then we recommend you put the model back into AD mode to reach a new equilibrium. In this configuration, this will also automatically reseed “dead” plant functional types in the initial file with a bit of leaf carbon to give those plant functional types another chance to grow under the new atmospheric forcing or model conditions."

Thanks for a series of responses.