Changes between Version 153 and Version 154 of Documentation/TrunkFunctionality4

Timestamp:

2024-05-29T09:11:05+02:00 (5 weeks ago)

Author:

luyssaert

Comment:

--

Documentation/TrunkFunctionality4

@@ -280 +280 @@
 Note that the min_vegfrac criterion could be the reason of why very small land cover changes occur. Another consequence is that the land cover fractions in the model are not exactly the same as those read in from the maps. Deviations should remain small and should not accumulate over time. Assume that in y0 the fraction of PFT2 = 0. In y1 the map tells us the fraction is half of min_vegfrac. The model will keep the PFT fraction to zero. The model and the map will no longer be in line with each other. In y2 the map tells us the fraction is twice min_vegfrac. The model will now accept the change. The model and the map will be in line with each other.
 
-'''hack_veget_max_new''' can be used to prescribe veget_max from run.def rather than a PFT map. This is a useful feature to debug simplified test cases with land cover changes.
+'''HACK_VEGET_MAX_NEW''' can be used to prescribe veget_max from run.def rather than a PFT map. This is a useful feature to debug simplified test cases with land cover changes. One possible approach to set up a simple test case is to run ORCHIDEE for 1 year (but could be any length depending on your needs) with IMPOSE_VEG = y, VEGET_UPDATE = 0Y. Set the SECHIBA_VEGMAX according to your test case (for example SECHIBA_VEGMAX__06=0.5 SECHIBA_VEGMAX__10=0.5 all others set to 0). Next set-up the model to start from the restart of the previous set-up. This new set-up should not be longer than 1y (the model should run for longer than 1 y but the hack will be implemented every year). Set IMPOSE_VEG = n (this is needed to make veget_update work), VEGET_UPDATE = 1Y (this is needed to make HACK_VEGET_MAX_NEW work), HACK_VEGET_MAX_NEW = y and now set FRAC_NOBIO_NEW and VEGET_MAX_NEW to your needs. For example VEGET_MAX_NEW__06 = 1 and VEGET_MAX_NEW__10 = 0.0 (note that VEGET_MAX_NEW is defined at the PFT level). For more complex test also FRAC_NOBIO_NEW can be set (defined at the pixel level). In the example above the 0.5 fraction of grasslands (PFT10) will be converted into summergreen deciduous forest (PFT6).