using CESM restart files and PFT fraction for mid-Holocene vegetation-climate feedback simulation

[zhangguangzhi]

I am conducting research on the impact of Holocene vegetation feedback on climate. To reduce computational time, I plan to use CESM’s official mid-Holocene coupled simulation restart files. To ensure that the CLM (Community Land Model) reaches equilibrium, I am considering three phases for my simulation experiments:

1. ADspinup (startup): Using CESM version 2.1’s mid-Holocene restart files as the findat file, along with my custom PFT fraction file.
2. postADspinup (hybrid): Using my custom PFT fraction file.
3. Normal run: Setting it as hybrid and also using my custom PFT fraction file.

I have the following questions:

1. Is it acceptable to use CESM’s official mid-Holocene restart files as the findat file for my ADspinup? My concern is that while GHG and Astronomical parameters are the same, the PFT fraction differs. Would this affect the equilibrium of the model in the spinup phase?
2. Given that I only need the equilibrium state for the mid-Holocene, do I still need the third phase of the simulation (the normal run)?

Thank you for your insights.

 

[oleson]

I personally am not familiar with the CESM 2.1 mid-Holocene simulations, but if the model version you are using is CESM2.1, then initializing a spinup with that restart fiile seems logical. But is that a coupled simulation? Are you going to spinup with offline atmospheric forcing or within the coupled model?

The normal run is basically an extension of the postADspinup. Generally, we reduce the amount of history output in the postADspinup to reduce disc space usage and then do a normal run with all of the history output we require.