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Changes between Version 16 and Version 17 of Documentation/TrunkFunctionality4

Timestamp:: 2020-03-09T14:23:57+01:00 (4 years ago)
Author:: luyssaert
Comment:: --

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Documentation/TrunkFunctionality4

-                      v16
+                      v17
 Following a disturbance (which could be a clear cut), tree species changes and forest management change can be prescribed or read from a map in ORCHIDEE-CAN. Set '''lchange_species''' = y, '''read_species_change_map''' = y, and '''read_desired_fm_map''' = y and specify the paths of those maps in the COMP/stomate.card. This functionality replaces the DGVM in areas where humans rather than nature govern species distribution, for example, Europe. Note that there are some constraints on the possible management changes. If the species is a conifer, for example, the new management strategy cannot be coppicing (fm=3). Anthropogenic species change has not been developed to work together with land cover change (this would require some good bookkeeping for veget_max). Forest management change has not been tested together with land cover change but because they affect different variables, i.e., '''forest_managed''' and '''veget_max''' combining both functionalities seems not overly complex.
 === Grasslands (CHECK) ===
 In the DOFOCO branch, grasslands were treated as evergreens as dead grasslands in winter at the time had too high of albedo compared to real grasslands.  After the work of Nicolas Vuichard, we have moved CAN back to deciduous phenology, trying to follow what is done in the TRUNK as closely as possible.  For the moment we are also using Nicolas's patch that enforces senescence if too many of the leaves are in the oldest leaf age class.  This patch is controlled by the LNVGRASSPATCH flag, and is set to T in the standard run.def.
+=== Grasslands (r6614) ===
+In terms of grassland phenology ORCHIDEE trunk 4 follows ORCHIDEE 3.0 as closely as possible. For the moment ORCHIDEE trunk 4 is also using Nicolas's patch that enforces senescence if too many of the leaves are in the oldest leaf age class.  This patch is controlled by the LNVGRASSPATCH flag, and is set to T in the standard run.def.
 Part of the turnover goes into the harvest pool (was that parameter extermalized?) -> simplified use of grasslands. Harvest goes into harvest_pool (just like wood) and its decomposition is accounted for in the fluxes from the product use pool.
 …
 All biomass harvest is recorded in a harvest variable '''harvest_pool''', this variable also stores the mass and dimensions of the harvest/mortality (absolute numbers thus accounting for the pixel area!). Related variables were introduced: '''harvest_type''', '''harvest_cut''', and '''harvest_area'''. Wood product pools and fluxes from wood and biomass decomposition are calculated in a separate module dedicated to wood use. The dimension of the wood use pools were externalized and can be changed to better address regional differences when aiming for regional simulations. The default 1, 10 and 100 year pools were replaced by 2, 17 and 50 years which is closer to the reality for Europe. For most parts of the world a 100 year wood pool is very optimistic.
 === Leaf area index map (r6614) ===
 Four flags have been identified that control the model behavior in terms of lai: '''ok_stomate''', '''ok_pheno''', '''impose_veg''' and '''read_lai'''. There is a 5th implicit flag which is whether restart files are used or not. If a restart file is used, the lai values will come from the sechiba restart file which is read at t=48. Given that each flag can take two values, we have 32 configurations in total. Out of these 32 configurations 10 are defined of which about 5 to 7 seem to be intended (for more details see Start and restart - Table 1). Many of the remaining 22 settings are inconsistent (i.e. running stomate to calculate a lai and reading an lai_map to prescribe lai), duplicate other settings, or would require further developments to work properly. Furthermore, the current code does not stop or warn when inconsistent settings are selected. The table (see Start and restart) proposes a scheme with 2 flags which can run with our without restart files, thus resulting in 8 different ways to control the lai in sechiba or the initial lai in stomate. The remaining 2 combinations are inconsistent and will stop the model.
 In the ORCHIDEE and ORCHIDEE-CN, canopy structure is prescribed by a single variable lai and the assumption of a turbid medium (Lambert-Beer). Consequently reading an lai value suffice to prescribe the entire canopy. In ORCHIDEE-CN-CAN, however, canopy structure has become a 3D property that can be calculated from the leaf biomass, stem biomass, the number of individuals and the assumptions that the trees follow a Poisson distribution in the horizontal plain, that the crowns are spherical and that the leaf biomass is uniformly distributed within the crowns.
 The functionality to simply prescribe an lai value (either through impose or by reading a map) will need to be replaced by functionality that prescribes or reads the biomass, leaf age, and number of individuals. Given that the current lai map is based on a previous ORCHIDEE run, the same approach could be used to generate a spatially explicit canopy map that contains biomass, individuals and leaf age distribution. Nevertheless, reading an observed lai, i.e., from MODIS, and using it to force ORCHIDEE-CN-CAN would require a substantial number of assumptions to turn an aggregated 1D lai value into a disaggregated 3D canopy at the PFT level.
+Four flags have been identified that control the model behavior in terms of lai: '''ok_stomate''', '''ok_pheno''', '''impose_veg''' and '''read_lai'''. There is a 5th implicit flag which is whether restart files are used or not. If a restart file is used, the lai values will come from the sechiba restart file which is read at t=48. Given that each flag can take two values, we have 32 configurations in total. Out of these 32 configurations 10 are defined of which about 5 to 7 seem to be intended (for more details see '''Start and restart - Table 1'''). Many of the remaining 22 settings are inconsistent (i.e. running stomate to calculate a lai and reading an lai_map to prescribe lai), duplicate other settings, or would require further developments to work properly. Furthermore, the current code does not stop or warn when inconsistent settings are selected. The table (see Start and restart) proposes a scheme with 2 flags which can run with our without restart files, thus resulting in 8 different ways to control the lai in sechiba or the initial lai in stomate. The remaining 2 combinations are inconsistent and will stop the model.
+In previous ORCHIDEE trunks, canopy structure is prescribed by a single variable called lai and the assumption of a turbid medium (Lambert-Beer). Consequently reading an lai value suffice to prescribe the entire canopy. In ORCHIDEE trunk 4, however, canopy structure has become a 3D property that can be calculated from the leaf biomass, stem biomass, the number of individuals and the assumptions that the trees follow a Poisson distribution in the horizontal plain, that the crowns are spherical and that the leaf biomass is uniformly distributed within the crowns.
+The functionality to simply prescribe an lai value (either through impose or by reading a map) will need to be replaced by functionality that prescribes or reads the biomass, leaf age, and number of individuals. Given that the current lai map is based on a previous ORCHIDEE run, the same approach could be used to generate a spatially explicit canopy map that contains biomass, individuals and leaf age distribution. Nevertheless, reading an observed lai, i.e., from MODIS, and using it to force ORCHIDEE trunk 4 would require a substantial number of assumptions to turn an aggregated 1D lai value into a disaggregated 3D canopy at the PFT level.
 === Land cover change (with age classes) (CHECK) ===