Changes between Version 136 and Version 137 of Documentation/TrunkFunctionality4

Timestamp:

2023-03-21T13:52:32+01:00 (16 months ago)

Author:

luyssaert

Comment:

--

Documentation/TrunkFunctionality4

@@ -182 +182 @@
 As an additional consistency check the time integral of the NBP (from 0 -> t) should equal the C and N stock at time step t. Comparing the time integral of NEP vs the all pools includes all the accumulated precision errors. If those errors would be random there would be no problem but they are more likely biases. Hence, when the fluxes and pools increase several order of magnitudes (e.g toward 1e4) and a small bias (1e-12) is integrated over 10,000 days (1e4) the divergence between the time integral of NEP and the pools will approach/exceed 1-8 and woukd stop the model. This is a fundamental problem related to machine precision and the way we do the calculations (think of the so called catastrophic rounding errors that may occur with floating numbers). For this reason this check is written to the history files but does not make the model crash. The user will have to decide whether (s)he is facing a precision error or a real bug. Fixing precision errors will require to improve the precision of the calculations in one or several subroutines.
 
+The variable MBC_NBP3_c was added to enable monitoring whether the NBP send to LMDZ in intersurf.f90 is identical to the NBP calculated in stomate_lpj.f90. If ERR_ACT=3 is used, the model will crash if the NBP send in intersurf differs from the NBP calculated in stomate_lpj.f90. Irrespective of the value of ERR_ACT, the mismatch between both NBPs will be send to MBC_NBP3_c.
+
 
 === Croplands ===