Use of Environmental Gradient
Data to Test Earth System Models
Melannie Hartman
Colorado State University
Fort Collins, Colorado, USA
CLIMMANI-INTERFACE Workshop
4-7 June 2013, Mikulov, Czech Republic
with contributions from:
William J. Parton
Colorado State University
Fort Collins, Colorado, USA
William Wieder and Gordon Bonan
National Center for Atmospheric Research
Boulder, Colorado, USA
OUTLINE
• Environmental Gradient Data Sets
• Examples of how these data sets have been used to test
Earth System Models
– may also involve model comparisons
• Models
Community Land Model version 4.0 (CLM4)
biogeophysics, hydrologic cycle, biogeochemistry, vegetation.
http://www.cesm.ucar.edu/models/clm/
Daily Century (DAYCENT)
ecosystem-level plant dynamics,
hydrology, biogeochemistry
Earth System Models: Many processes, many scales
Environmental Gradient Data Sets
• FLUXNET* Global network of micrometeorological tower sites
that use eddy covariance methods to measure the exchanges
of carbon dioxide, water vapor, and energy between terrestrial
ecosystems and the atmosphere.
500+ tower sites - 30 regional networks – 5 continents
• Ecosystem Model-Data Intercomparison (EMDI) *
NPP field measurements world-wide
(Olson et al., 2001)
• Long-term Intersite Decomposition Experiment Team (LIDET)
10-year, 28-site study of litter decomposition and N dynamics
(Gholz et al., 2000; Parton et al., 2007; Harmon et al., 2009).
• Harmonized World Soils Database (HWSD)
global SOC, soil texture, and pH
(FAO, 2012)
*ORNL Distributed Active Archive Center
http://daac.ornl.gov/
Environmental Gradient Data Sets (cont’d)
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1-km NPP and GPP derived from MODIS satellite observations
– Zhao et al. 2005, 2006
MODIS and EMDI 10x10 km NPP
– gridded, global NPP data by plant part
– wood, fine roots, coarse roots, and leaves
MODIS and EMDI annual plant N and P uptake
– gridded, global data (10x10 km)
N and P Mineralization
– gridded, global data (10x10 km)
EMDI Plant NPP
– 5000 observations
– 0.5° x 0.5° global map
MODIS
• Great Plains Grassland NPP
- 12,000 observations
- spatial map of NPP
• Great Plains Grassland and cultivated SOIL C
- 1,000+ observations
- gridded spatial maps and regressions
http://daac.ornl.gov/FLUXNET/fluxnet.shtml
FLUXNET TOWER SITES
~500 eddy covariance tower sites - 30 regional networks – 5 continents
Global, spatially gridded GPP and latent heat flux are upscaled from the FLUXNET tower data
(Control )
(revised two‐stream radiative transfer)
(RAD and revised leaf photosynthesis)
Bonan et al. (2011) Journal of Geophysical Research: Improving canopy processes in the Community Land Model
version 4 (CLM4) using global flux fields empirically inferred from FLUXNET data
FLUXNET: Latitudinal Zonal Means
Bonan et al. (2011) Journal of Geophysical Research
EMDI
EMDI: NPP Observations and Model Comparison
933 site-level
measurements
CLM
Randerson et al. (2009)
Global Change Biology
10-year, 28-site study of litter decomposition and N dynamics
http://andrewsforest.oregonstate.edu/research/intersite/lidet.htm
Long-Term Intersite Decomposition Experiment (LIDET)
Observations
10-year study of litter dynamics for a variety of litter types placed in different environments
 20 sites: 2 tundra, 2 boreal forest, 5 conifer forest, 3 deciduous forest, 3 tropical
forest, 2 humid grassland, 3 arid grassland
 9 litter types (6 species of leaves, 3 species of root) that vary in chemistry
Litter bags sampled once a year for C and N
Model simulations
 CLM4cn, DAYCENT
 Follow a cohort of litter (100 g C m-2) deposited on October 1
 Specified climatic decomposition index (CDI) to account for temperature and moisture
 Soil mineral nitrogen
 % C mass remaining (decomposition rates)
 Fraction of initial N
(mineralization/immobilization)
Bonan et al (2013)
Global Change Biology
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Leaf litter mass loss – conifer forest
5 sites & 6 leaf litter types
Shown are the site x litter
mean and ± 1 SD
CLM underestimates
carbon mass remaining
(overestimates mass
loss), especially during
first several years. This
is common to all sites.
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Bonan et al (2013) Global Change Biology
LIDET: Leaf litter mass loss – all sites
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Bonan et al (2013) Global Change Biology
LIDET: Litter Nitrogen dynamics
Maple, 0.81 %N
Observations are sampled once per year. Shown are data for maple
leaf litter at all biomes except arid grassland. Model data are
sampled similar to the observations.
CLM4cn overestimates immobilization. Larger
biases for leaf litter types with lower initial %N
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Bonan et al (2013) Global Change Biology
HWSD: Steady-State Analysis of Global Soil Carbon Pools
Observed litterfall increases soil C
compared with CLM4 litterfall
HWSD (0-100cm), 1259 PgC
CLM4 analytical + obs. litter inputs, 746 PgC
Wieder et al., in revision
CLM4 spinup, 502 PgC
DayCent analytical + obs. litter inputs, 978 PgC
Observationally derived litter inputs from Matthews, E. (1997)
HWSD: Latitudinal Zonal Mean of Soil Organic C density
HWSD (0-100cm) 1259 PgC
DayCent, 978 Pg C
CLM4, 746 Pg C
Wieder et al., in revision
Summary
• These data are valuable tools to guide terrestrial
biosphere model development and evaluation
• Field Measurements, Upscaled global gridded
products, or MODIS derived
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NPP & GPP
latent heat flux
litter decomposition (%C remaining, fraction of initial N)
soil carbon stocks
N and P plant uptake
N and P mineralization
References
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Bonan, G. B., M. D. Hartman, W. J. Parton, and W. R. Wieder. 2013. Evaluating litter decomposition in earth system models
with long-term litterbag experiments: an example using the Community Land Model version 4 (CLM4). Global Change
Biology 19:957-974.
Bonan, G. B., P. J. Lawrence, K. W. Oleson, S. Levis, M. Jung, M. Reichstein, D. M. Lawrence, and S. C. Swenson. 2011.
Improving canopy processes in the Community Land Model version 4 (CLM4) using global flux fields empirically inferred from
FLUXNET data. Journal of Geophysical Research-Biogeosciences 116.
FAO, IIASA, ISRIC, ISSCAS, and JRC (2012), Harmonized World Soil Database (version 1.2), edited by FAO, Rome, Italy and
IIASA, Laxenburg, Austria.
Gholz, H. L., D. A. Wedin, S. M. Smitherman, M. E. Harmon, and W. J. Parton. 2000. Long-term dynamics of pine and
hardwood litter in contrasting environments: toward a global model of decomposition. Global Change Biology 6:751-765.
Harmon, M. E., W. L. Silver, B. Fasth, H. Chen, I. C. Burke, W. J. Parton, S. C. Hart, W. S. Currie, and Lidet. 2009. Long-term
patterns of mass loss during the decomposition of leaf and fine root litter: an intersite comparison. Global Change Biology
15:1320-1338.
Matthews, E. (1997), Global litter production, pools, and turnover times: Estimates from measurement data and regression
models, J. Geophys. Res., 102(D15), 18771-18800.
Olson RJ, Scurlock JMO, Prince SD, Zheng DL, Johnson KR (2001) . NPP Multi-Biome: NPP and Driver Data for Ecosystem
Model-Data Intercomparison. Available on- line [http://www.daac.ornl.gov] from the Oak Ridge National Laboratory
Distributed Active Archive Center, Oak Ridge, Tennessee, USA.
Parton, W., W. L. Silver, I. C. Burke, L. Grassens, M. E. Harmon, W. S. Currie, J. Y. King, E. C. Adair, L. A. Brandt, S. C. Hart, and
B. Fasth. 2007. Global-scale similarities in nitrogen release patterns during long-term decomposition. Science 315:361-364.
Randerson, J. T., F. M. Hoffman, P. E. Thornton, N. M. Mahowald, K. Lindsay, Y. H. Lee, C. D. Nevison, S. C. Doney, G. Bonan, R.
Stockli, C. Covey, S. W. Running, and I. Y. Fung. 2009. Systematic assessment of terrestrial biogeochemistry in coupled
climate-carbon models. Global Change Biology 15:2462-2484.
Wieder,, W.R., J. Boehnert,, and G.B. Bonan Evaluating soil biogeochemistry parameterizations in Earth system models with
observations, Global Biogeochemical Cycles, in revision
Zhao M, Running SW, Nemani RR (2006) Sensitivity of Moderate Resolution Imaging Spectroradiometer (MODIS) terrestrial
primary production to the accuracy of meteorological reanalyses. Journal of Geophysical Research – Biogeosciences, 111,
G01002, doi: 10.1029/2004JG000004.
Zhao MS, Heinsch FA, Nemani RR, Running SW (2005) Improvements of the MODIS terrestrial gross and net primary
production global data set. Remote Sensing of Environment, 95, 164–176. EVALUATING TERRESTRIAL BIOGEOCHEMISTRY
MODE L S 2483 r 2009
Bonan et al. 2011: Improving canopy processes in the Community Land Model version 4
(CLM4) using global flux fields empirically inferred from FLUXNET data
EMDI
Steady-state analysis
Observed litterfall increases soil C
compared with CLM4cn litterfall
Base DAYCENT
(0-20 cm)
“Deep” DAYCENT
(0-100 cm)
CLM4cn has more soil carbon than DAYCENT, but “deep”
DAYCENT (0-100 cm) accumulates the most carbon
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