Carbon mass conservation problem

[nvuilsce]

When performing spinup run for TRENDY, I diagnosed a problem in the closure of the carbon balance. nbp variable has a value of -0.02 Pg/yr-1 (= a source for surface to atm) over the 10 year of climate forcings (used for the spinup) while stocks of carbon increase of ~0.02 Pg/yr-1.

[nvuilsce]

There is a bug in stomate_npp line 301
It should be
biomass(i,j,icarbres,icarbon) = biomass(i,j,icarbres,icarbon) + &

bm_alloc_tot(i,j) - resp_maint(i,j) * dt

not "- bm_alloc_tot"

but this has no impact on the probleme reported.

[jgipsl]

The small correction described in the comment is commit in rev [4728].

The ticket is still not fixed but set to milestone ORCHIDEE 3.0

[aducharne]

Linked to #456

[jgipsl]

I checked in simulation FG1low.6216.irene recent spinup done at irene using revision 6216 on the trunk, default set up as in SPINUP_ANALYTIC (Trendy setup using v5.3 forcings). nbp global mean over the last 10 years in this simulation is 0.027 PgC/yr.

[jgipsl]

According to the ORCH meeting 10/12/2019:

The issue will not be further investigated in current version of the trunk, 3.0. When branch CN-CAN has been integrated in the trunk, this kind of problem could more easily be searched for. This ticket is related to #419 and solving that ticket might solve this one as well.