Design Document for L13: ELMv1-CTC-CNP updates used in Land-BGC Intercomparison
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 | Updates and parameterization changes made for the ELMv1-CTC-CNP model in advance of the Land-BGC Intercomparison simulations |
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| 4.Equ | |
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Title: L13: ELMv1-CTC-CNP updates used in Land-BGC Intercomparison
Requirements and Design
E3SM Land Group
Date:
Summary
- Introduce a soil order-based parameterization of mortality in tropical forests
- Remove the second round of nutrient uptake for N and P
- Modification of plant N and C storage pool dynamics, and introduction of plant P storage pool dynamics
- Modification of subsurface drainage parameterization
- Improve the parameterization of stress-deciduous phenology
Requirements
Requirement: Represent observed variation in tropical forest mortality
Date last modified:
Contributors: Xiaojuan Yang, Peter Thornton, Daniel Ricciuto
Field studies have shown that edaphic factors exert a strong influence on tree mortality in tropical forests, with lower mortality in highly weathered Oxisols, and higher mortality in younger soils.
Quesada, C. A. et al. Basin-wide variations in Amazon forest structure and function are mediated by both soils and climate. Biogeosciences 9, 2203–2246 (2012)
Galbraith D, Malhi Y, Affum-Baffoe K, Castanho ADA, Doughty CE, et al. 2013. Residence times of woody biomass in tropical forests. Plant Ecol. Divers. 6:139–57
Requirement: Remove redundant implementation of nutrient uptake
Date last modified:
Contributors: Xiaojuan Yang, Peter Thornton, Daniel Ricciuto
The original implementation of the relative demand hypothesis for competition between multiple plant and microbial components for available mineral nutrient resources included a single reconciliation of plant and microbial demand. In a later modification of that approach, a redundant second round of nutrient uptake was added. This redundant uptake implementation should be removed.
Requirement: Revise the handling of plant non-structural storage pools, in correspondence with observations
Date last modified:
Contributors: Peter Thornton, Daniel Ricciuto, Xiaojuan Yang
Plant carbon uptake in excess of allocation to new growth is retained in a non-structural carbohydrate pool, which turns over on a specified time scale, based on experimental evidence from Metcalfe et al. (2017).
Metcalfe, D. B., D. Ricciuto, S. Palmroth, C. Campbell, V. Hurry, J. F. Mao, S. G. Keel, S. Linder, X. Y. Shi, T. Nsholm, K. E. A. Ohlsson, M. Blackburn, P. E. Thornton and R. Oren (2017). "Informing climate models with rapid chamber measurements of forest carbon uptake." Global Change Biology 23(5): 2130-2139.
Requirement: Improve subsurface drainage parameterization based on observations
Date last modified:
Contributors: Daniel Ricciuto, Peter Thornton
Recent model-data evaluation effort showed that an earlier parameterization of subsurface drainage, used in CLM4.0, is more appropriate than the parameterization in CLM4.5, which served as the branch point for ELMv1 (Duarte et al., 2017).
Duarte, H. F., B. M. Raczka, D. M. Ricciuto, J. C. Lin, C. D. Koven, P. E. Thornton, D. R. Bowling, C. T. Lai, K. J. Bible and J. R. Ehleringer (2017). "Evaluating the Community Land Model (CLM4.5) at a coniferous forest site in northwestern United States using flux and carbon-isotope measurements." Biogeosciences 14(18): 4315-4340.
Requirement: Improve representation of stress-deciduous phenology
Date last modified:
Contributors: Daniel Ricciuto
Recent model evaluation indicated improved performance of the stress-deciduous phenology model by introducing a critical rainfall threshold to trigger leaf-on (Dahlin et al. 2015).
Dahlin, K. M., R. A. Fisher and P. J. Lawrence (2015). "Environmental drivers of drought deciduous phenology in the Community Land Model." Biogeosciences 12(16): 5061-5074.
Algorithmic Formulations, and Design Implementation
Design Solution: Represent observed variation in tropical forest mortality
Date last modified:
Contributors: Xiaojuan Yang, Peter Thornton, Daniel Ricciuto
Modified CNGapMortalityMod.F90 to implement the requirement according to observed patterns of soil order and tree mortality.
Design Solution: Remove redundant implementation of nutrient uptake
Date last modified:
Contributors: Xiaojuan Yang, Peter Thornton, Daniel Ricciuto
Modified CNAllocationMod.F90 to remove the second-pass nutrient uptake for N and P, restoring the intended design implementation.
Design Solution: Revise the handling of plant non-structural storage pools, in correspondence with observations
Date last modified:
Contributors: Peter Thornton, Daniel Ricciuto, Xiaojuan Yang
Modified the following files: src/biogeochem: CNAllocationMod.F90, CNMRespMod.F90 [C,N,P]StateUpdate[1,2,3].F90, CNGapMortalityMod.F90, CNFireMod.F90, [Carbon,Nirogen,Phosphorus]FluxType.F90
src/dyn_subgrid: dynConsBiogeochemMod.F90, dynHarvestMod.F90
main/pftvarcon.f90
Implemented the C storage pool dynamics described in the requirement. updated the N and P storage pool implementations to account for disturbance and mortality effects.
Design Solution: Improve subsurface drainage parameterization based on observations
Date last modified:
Contributors: Daniel Ricciuto, Peter Thornton
Modified the following files: biogeophys/SoilHydrologyMod.F90, and main/pftvarcon.f90.
Reverted the code to the CLM 4.0 implementation.
Design Solution: Improve representation of stress-deciduous phenology
Date last modified:
Contributors: Daniel Ricciuto
Modified the following files: biogeophys/SoilHydrologyMod.F90, and main/pftvarcon.f90.
Added the necessary dependence on critical rainfall threshold for leaf-on.
Planned Verification and Unit Testing
Verification and Unit Testing: Expert review
Date last modified:
Contributors: Peter Thornton, Daniel Ricciuto, Xiaojuan Yang
The named experts provided extensive review of each other's work, to verify that the design and implementations met the stated requirements. Model testing at each stage of implementation was used to verify that intended changes were correctly implemented, and that unintended changes were avoided.
Planned Validation Testing
Validation Testing: Evaluation with ILAMB and additional model-data metrics
Date last modified:
Contributors:
Peter Thornton, Daniel Ricciuto, Xiaojuan Yang
The package of changes described here is being evaluated in a large set of offline simulations, with comparison against numerous observational constraints in the ILAMB framework, as part of the ongoing Land-BGC Intercomparison process. That process includes additional metrics, beyond ILAMB, which are so far not known to the model developers.
Planned Performance Testing
Performance Testing: Offline simulations on multiple platforms
Date last modified:
Contributors: Daniel Ricciuto
Many performance simulations have already been performed, in tests leading up to the Land-BGC simulations, and for the set of global offline simulations themselves.