ACCESS spin-up with CABLE-POP

Assess spin-up options / strategy for ACCESS when including POP/POPLUC.

Current CABLE-POP spin-up includes an analytical spinup for POPLUC after CABLE spin-up is completed. @Juergen suggests this POPLUC spin-up is worth having a closer look. His understanding is that it does not run the biophysics but initiates the age distribution in the secondary forest. It is the last step before the actual run starts in 1700.

For ACCESS, can we do a CABLE-POP offline spin-up (perhaps with ACCESS meteorology), next run offline from 1700-1850 and then effectively pause the tree demography to spin-up ACCESS and run pre-industrial? Might need to iterate between offline and online a few times?