Minutes of the meeting of May 31, 2018

• Presents: Fabienne, Vladislav, Philippe P, Nicolas Viovy, Nicolas Vuichard
• Problem in the phenology:
  • Here an illustration of the problem:
  • Problem in the way to compute the mean LAI per PFT in the mapper: The new diagnostic developed by Vlad shows the contribution of each PFT to the total LAI for specific regions (latitudinal bands, continents, ...). This is sensitive to the land use map used and is not the diagnostic expected (ie mean LAI for each PFT for a specific region).
    Action => Vlad will correct this in order to clearly identify which PFT(s) have a very bad phenology
  • Fabienne agrees on working on this issue. Nicolas Vui will give her the information needed for running this version of ORCHIDEE (next Thursday morning)
  • Several actions related to this problem of phenology
    • To modify specific parameters related to the allocation and/or the senescence. Based on the diagnostic, the problem might be only related to the leaf onset, which seems to slow in the temperate areas. Because the leaf onset is not enough abrupt, due to the residence time of the biomass, the problem at the leaf onset may impact as well the senescence phase.
    • To ensure that there is no change in the allocation module of the CN-CAN version compared to the CN version
    • And/or : To switch on the allocation module of CN and to switch on the one from CN-CAN

• Set-up of the coupled simulations LMDzOR:
  • For the moment, only one LMDzOR simulation has been done, in which the leaf C/N ratio was precribed with default values.
  • Simulations with dynamical C/N ratio have to be launched: Vlad will do one soon, starting from scratch. One may also envisage to launch one but starting from a restart file for orchidee component.
  • A simulation with C/N fix could also be done but with more realistic C/N ratio (spatialized) than those used in the first simulation.
• Problem in the autotrophic respiration
  • The share between maintenance and growth respiration is almost the opposite than the one expected.
  • There is an additional source of respiration related to the excess of labile Carbon when this pool reaches too high values. The respiration term is included into the growth respiration. This does not help to tune the maintenance and growth respiration terms.
  • Action: to remove the addition respiration related to the labile C and to diagnose the contribution of growth and maintenance respiration to the autotrophic respiration

Minutes of the meeting of June, 7

Presents: Patricia, Sebastiaan, Fabienne, Vladislav, Nicolas Viovy, Philippe P., Nicolas Vuichard

• Problem of phenology of grasslands
  • About the differences in the routine dealing with allocation (stomate_growth_fun_all) between the CN version and CN-CAN version, Sebestiaan don’t think there are significant changes. The main difference is a difference in the parametrisation: In CN-CAN, grasslands are evergreen vegetation while they are deciduous in the CN version.
    

=> one test simulation could be launched in force mode, setting the grasslands as evergreen

• The new diagnostic for looking at seasonal variation of LAI per PFT over specific regions developed by Vlad is not ready yet.
• Instead, we looked at the LAI maps generated per season (DJF,MAM,JJA,...) which are available on the mapper. We have seen that the LAI of PFT 10 for the coupled simulation with CN version and CN fix compares relatively well to the one from the coupled simulation with the standard ORCHIDEE.
  

LMDzOR Trunk	LMDzOR CNfix

In contrast, the LAI from the simulation in force mode with CN version and CNdyn is much lower than the one with the ORCHIDEE standard.

ORCHIDEE Trunk	ORCHIDEE CNdynamic

This may indicate that the problem in the phenology of grasslands is not strictly speaking a phenology problem but a problem of N availability which indirectly impacts on the LAI development.

=> We could run a new simulation with CN version and CN fix in force mode, in order to compare it with the simulation with CN dyn and also with the gimms product.

=> Check how is set the flag ALWAYS_INIT in our simulations with CN dynamic. One may wonder if the low LAI simulation with CNdyn are due to past conditions (ie early 20th or late 19th) for N fertilisation and N deposition or if also for present day conditions, the grasses have difficulties for growing.