L6_Design document for addition of phosphorus cycle
The Design Document page provides a description of the algorithms, implementation and planned testing including unit, verification, validation and performance testing. Please read Step 1.3 Performance Expectations that explains feature documentation requirements from the performance group point of view.
Design Document
In the table below 4.Equ means Equations and Algorithms, 5.Ver means Verification, 6.Perf - Performance, 7. Val - Validation, 
- competed, 
- in progress, 
- not done
Overview table for the owner and an approver of this feature
1.Description | Addition of phosphorus cycle in ALM, coupled to carbon and nitrogen cycles |
| 2.Owner | Xiaojuan Yang |
| 3.Created | |
| 4.Equ | |
| 5.Ver | |
| 6.Perf | |
| 7.Val | |
| 8.Approver | Peter Thornton, William Riley (Unlicensed) |
| 9.Approved Date | |
| V1.0 | Accepted |
Title: Implement prognostic phosphorus cycle into ACME land model
Requirements and Design
ACME Land Group
Date: 09/15/2015
Summary
The importance of nutrient in regulating carbon(C)-climate feedbacks has been increasingly recognized. While ACME V0 includes prognostic nitrogen(N) cycle and C-N interactions, phosphorus(P), the most limiting nutrient in productive lowland tropical forests, has yet to be considered. Here we implement prognostic P cycle and C-N-P interactions into ACME land model. This implementation will lead to a more accurate representation of C-nutrient interactions in ACME.
References:
Yang, X., Thornton, P. E., Ricciuto, D. M., and Post, W. M.: The role of phosphorus dynamics in tropical forests – a modeling study using CLM-CNP, Biogeosciences, 11, 1667-1681, doi:10.5194/bg-11-1667-2014, 2014.
Yang, X., Post, W. M., Thornton, P. E., and Jain, A.: The distribution of soil phosphorus for global biogeochemical modeling, Biogeosciences, 10, 2525-2537, doi:10.5194/bg-10-2525-2013, 2013.
Requirements
Requirement: Implement prognostic phosphorus cycle
Date last modified: 09/15/2015
Contributors: @ Xiaojuan Yang
All the needed phosphorus state and flux variables are added. Both geochemical and biological phosphorus processes are represented.
Requirement: Represent C-N-P interactions
Date last modified: 09/15/2015
Contributors: @ Xiaojuan Yang
This includes (1) P limitation on carbon cycle processes (2) biochemical mineralization through phosphatase activity
Requirement: Resolve N limitation vs P limitation
Date last modified: 09/15/2015
Contributors: @ Xiaojuan Yang
With both N and P in the model, N limitation vs P limitation is resolved to represent overall nutrient constraint on carbon cycle processes
Requirement: Model initialization for various P pools
Date last modified: 09/15/2015
Contributors: @ Xiaojuan Yang
Phosphorus cycle operates on geological time scales, it is not reasonable to spinup the model for tens of millions of years for model initialization. Instead we initialize the slow P pools globally with P maps that was generated(Yang et al., 2013)
Algorithmic Formulations
Design solution: Implement prognostic phosphorus cycle
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
All algorithmic formulations can be found in section 2.1.3 and 2.1.4 in Yang et al. (2014)
Design solution: Represent C-N-P interactions
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
All algorithmic formulations can be found in section 2.1.3 and 2.1.4 in Yang et al. (2014)
Design solution: Resolve N limitation vs P limitation
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
All algorithmic formulations can be found in section 2.1.2 in Yang et al. (2014)
Design solution: Model initialization for various P pools
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
The initialization maps can be found in Yang et al.(2013)
Design and Implementation
Implementation: Implement prognostic phosphorus cycle
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
P state and flux data types have been added. P state update subroutines have been added. Representation of Vegetation, litter, and soil organic matter P dynamics have been added. Inorganic P dynamics have been added
The following subroutines have been modified/added to include phosphorus cycle
• models/lnd/clm/src/biogeochem/CNAllocationMod.F90
• models/lnd/clm/src/biogeochem/CNBalanceCheckMod.F90
• models/lnd/clm/src/biogeochem/CNDecompCascadeCNMod.F90
• models/lnd/clm/src/biogeochem/CNDecompCascadeConType.F90
• models/lnd/clm/src/biogeochem/CNDecompMod.F90
• models/lnd/clm/src/biogeochem/CNEcosystemDynMod.F90
• models/lnd/clm/src/biogeochem/CNGapMortalityMod.F90
• models/lnd/clm/src/biogeochem/CNPhenologyMod.F90
• models/lnd/clm/src/biogeochem/CNPrecisionControlMod.F90
• models/lnd/clm/src/biogeochem/CNSoilLittVertTranspMod.F90
• models/lnd/clm/src/biogeochem/CNStateType.F90
• models/lnd/clm/src/biogeochem/CNWoodProductsMod.F90
• models/lnd/clm/src/biogeochem/PDynamicsMod.F90
• models/lnd/clm/src/biogeochem/PStateUpdate1Mod.F90
• models/lnd/clm/src/biogeochem/PStateUpdate2Mod.F90
• models/lnd/clm/src/biogeochem/PStateUpdate3Mod.F90
• models/lnd/clm/src/biogeochem/PhosphorusFluxType.F90
• models/lnd/clm/src/biogeochem/PhosphorusStateType.F90
• models/lnd/clm/src/main/EcophysConType.F90
• models/lnd/clm/src/main/SoilorderConType.F90
• models/lnd/clm/src/main/clm_driver.F90
• models/lnd/clm/src/main/clm_initializeMod.F90
• models/lnd/clm/src/main/clm_varctl.F90
• models/lnd/clm/src/main/clm_varpar.F90
• models/lnd/clm/src/main/controlMod.F90
• models/lnd/clm/src/main/pftvarcon.F90
• models/lnd/clm/src/main/restFileMod.F90
• models/lnd/clm/src/main/soilorder_varcon.F90
Implementation: Represent C-N-P interactions
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
The following subroutines have been modified or added
models/lnd/clm/src/biogeochem/CNDecompMod.F90
models/lnd/clm/src/biogeochem/CNAllocationMod.F90
models/lnd/clm/src/biogeochem/PDynamicsMod.F90
Implementation: Resolve N limitation vs P limitation
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
Implementation: Model initialization for various P pools
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
This is done by modifying the restart file before normal spinup
Planned Verification and Unit Testing
Verification and Unit Testing: Implement prognostic phosphorus cycle
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
Various component of the model has been tested against observations. For example, P dynamics during decomposition has been evaluated against CIDET dataset. Representation of biochemical mineralization has been evaluated against multiple observations.
Planned Validation Testing
Validation Testing: Implement prognostic phosphorus cycle
Date last modified: 09/16/2015
Contributors: Xiaojuan Yang
Model simulated phosphorus pools and fluxes will be evaluated against available observations such as Hedley P database(Yang et al., 2011). Other site level evaluations will be using (1) fertilization experiment along Hawaii chronosequence (2) sites along a P availability gradient in the Amazon basin. ILAMB will be used for regional and global evaluations. Other remote sensing products will also be used.
Planned Performance Testing
Performance Testing: Implement prognostic phosphorus cycle
Date last modified: 09/16/2015
Contributors: (add your name to this list if it does not appear)
Computation performance will be evaluated using the built-in timing tools with both offline and coupled global simulations.