Changes between Version 2 and Version 3 of DevelopmentActivities/ORCHIDEE-hydraulicArch
- Timestamp:
- 2021-10-09T16:24:09+02:00 (3 years ago)
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DevelopmentActivities/ORCHIDEE-hydraulicArch
v2 v3 3 3 == Meeting the 07 October 2021: comparison of Julien and Yitong schemes = 4 4 5 The purpose of the meeting was to compare Yitong Yao’s model with Julien Alléon’s one in order to : 6 - Understand the differences between both models ; 7 - Prepare a strategy in order to implement only one “mixed” model in ORCHIDEE_trunk. 5 The purpose of the meeting was to compare Yitong Yao’s model with Julien Alléon’s one in order to i) Understand the differences between both models and ii) prepare a strategy in order to implement only one “mixed” model in ORCHIDEE_trunk. 8 6 9 7 The meeting was organised around the presentation of the two models and the discussion on the advantages/drawbacks of each model: … … 11 9 - [attachment:Julien_Présentation.pdf Julien presentation] 12 10 13 Summary of the differences: 14 - Starting point 11 '''Summary of the differences:''' 12 - Starting point: 15 13 - Yitong: Emilie Joetzjer’s previous version of the hydraulic architecture in the module hydraulic_arch.f90. This previous version was more a proof about the necessity of introducing and hydraulic architecture than a clean implemented model as ORCHIDEE would need. 16 14 - Julien: New model based on ORCHIDEE_trunk version of May 2020. New subroutines introduced in hydrol module. 17 15 - Overall scheme: Both scheme rely on the description of the water transport from soil/root interface towards leaves thanks to a resistance/capacitance scheme. 18 - Root absorption 16 - Root absorption: 19 17 - Yitong: Rely on a development by Emily which, in addition to a soil/root resistance based on soil conductivity and root biomass, adds a weighting of the absorption according to the amount of water present in each layer. The idea is to weight more by the amount of water than by the root biomass. 20 18 - Julien: Two ways to model root absorption: … … 22 20 - Classic root absorption scheme relying on a dynamic resistance 23 21 - Transport through canopy 24 - Resistances 22 - Resistances: 25 23 - Yitong: Dynamic resistances linked to the water potential at each stage 26 24 - Julien: fixed resistances 27 - Capacitances 25 - Capacitances: 28 26 - Yitong: fixed values 29 27 - Julien: Dynamic values linked to the water potential of each storage pool. 30 - Stomatal conductance T 31 wo decoupled stomatal conductances for assimilation and water control. Only the one that controls water is linked to leaf water potential One stomatal conductance calculated thanks to the leaf water potential. The conductance controls assimilation and water supply. 32 Resolution method Global method: 33 The scheme calculates transpiration demand and supply. If the supply does not reach the demand, energy budget is recalculated (mleb has to iterate to converge towards the supply). 28 - Stomatal conductance: 29 - Yitong: Two decoupled stomatal conductances for C assimilation and water control. Only the one that controls water is linked to leaf water potential 30 - Julien: One stomatal conductance calculated thanks to the leaf water potential. The conductance controls assimilation and water supply. 31 - Resolution method: 32 - Yitong; Global method: the scheme calculates transpiration demand and supply. If the supply does not reach the demand, energy budget is recalculated (enerbil or mleb has to iterate to converge towards the supply). Inside the model: Iteration process in order to converge towards the fluxes at each stages. Uses minpack package for the resolution 33 - Julien: Resolution without iterations based on prediction/correction schemes for differential equations and estimation/corrections for non differential equations. ==> Causes instabilities. 34 34 35 Inside the model: 36 Iteration process in order to converge towards the fluxes at each stages. Uses minpack package for the resolution Resolution without iterations based on prediction/correction schemes for differential equations and estimation/corrections for non differential equations. 37 38 • Causes instabilities. 39 40 Main advantage Dynamic resistances Resolution method 41 Main drawback Resolution method Instability 42 43 Discussion : 35 '''Discussion:''' 44 36 Both models answer to a precise need which led to the previous choices. 45 37 Both models seem to have good results on the site studied.
