Towards a robust representation of
nutrient control of the land carbon
cycle: Formulation and numerics
Jinyun Tang, Bill Riley and Qing Zhu
3/14/2017
NCAR Land Working Group Meeting
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Theme of biogeochemistry
ENzyme
ATP
C-N-P
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NCAR Land Working Group Meeting
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Not easy to do it well
Parameterization
Initial and
boundary forcing
Mechanistic
formulation
Numerical
encoding
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NCAR Land Working Group Meeting
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The plant-soil-microbe nutrient
competition
Roots
Microbes
Phosphate
Soil minerals
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NCAR Land Working Group Meeting
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The plant-soil-microbe nutrient
competition
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
5
The plant-soil-microbe nutrient
competition
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
6
The plant-soil-microbe nutrient
competition
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
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The plant-soil-microbe nutrient
competition
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
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The competition conundrum
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NCAR Land Working Group Meeting
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The competition conundrum
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NCAR Land Working Group Meeting
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Two-step plant-soil-microbe nutrient
competition: step one
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
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Two-step plant-soil-microbe nutrient
competition: step two
Roots
Microbes
Phosphate
Soil minerals
3/14/2017
NCAR Land Working Group Meeting
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The Equilibrium Chemistry
Approximation Theory for nutrient
competition
Step one
3/14/2017
Step two
NCAR Land Working Group Meeting
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The Equilibrium Chemistry
Approximation Theory for nutrient
competition
Tang and Riley, 2013
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NCAR Land Working Group Meeting
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The Equilibrium Chemistry
Approximation Theory for nutrient
competition
Tang and Riley, 2013
3/14/2017
NCAR Land Working Group Meeting
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ECA is quite good: nitrogen
competition
Zhu et al., 2016
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NCAR Land Working Group Meeting
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SUPECA: extended ECA for more realistic
substrate-competitor networks
Tang and Riley, 2017
3/14/2017
NCAR Land Working Group Meeting
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Application for aerobic decomposition
Tang and Riley, 2017
3/14/2017
NCAR Land Working Group Meeting
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Mechanistic
formulation
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Numerical
encoding
NCAR Land Working Group Meeting
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The substrate limitation problem
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NCAR Land Working Group Meeting
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The substrate limitation problem
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NCAR Land Working Group Meeting
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Three different ways
MNL
PNL
NUL
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NCAR Land Working Group Meeting
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Small difference in fast response
variables
10-year mean for 1991-2000 historical run
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NCAR Land Working Group Meeting
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Large differences for slow response
variables
Historical run
3/14/2017
RCP4.5 atmospheric CO2 forcing
NCAR Land Working Group Meeting
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Poor numerical implementation could
be fatal: one more example
Right
Wrong
Migoni et al., 2012
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Summary
• It’s critical to
- get mechanistic formulations consistent with
the processes
- get the numeric encoding consistent with the
mechanistic formulations
• Existing uncertainty analysis of
parameterization and initial boundary
conditions could be severely biased.
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NCAR Land Working Group Meeting
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NCAR Land Working Group Meeting
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