managed by ut-battelle for the department of energy estimating the north american carbon balance...

Managed by UT-Battellefor the Department of Energy

Estimating the North American Carbon Balance

Using Inter-Comparison Among Inversions, Regional Terrestrial Biogeochemistry Models, and Observational

Data

Wilfred Post, Deborah Huntzinger, Kenneth Davis, Brett Raczka, Daniel Hayes, Anna Michalak, Yaxing Wei,

Andrew Jacobson , Robert Cook, and North American Carbon Program Regional-

Interim Synthesis Participants

2 Managed by UT-Battellefor the Department of Energy Presentation_name

North America Carbon Program Synthesis Objectives

Utilize new and emerging NACP research findings to develop a picture of the current state of the North America carbon cycle

Identify continental scale carbon sources/sinks

Characterize continental scale inter-annual variation

Assess our capability of modeling and measuring large scale carbon cycle dynamics

4 Managed by UT-Battellefor the Department of Energy

Data sets assembled and regridded for comparison with models

MODIS monthly GPP, annual NPP

Soil C from surveys

Inventory based C pool and flux estimates– Forest biomass from inventory

– Crop NPP from crop yield data

Comparison with eddy flux – crossover model runs with Site Synthesis

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Participating Models

19 TBMs

Models differ in:– Prognostic versus diagnostic

– Driver data

– Vegetation and soil properties

– Photosynthetic formulation

– # of carbon pools, soil carbon decomposition dynamics

– Processes included, etc.

25 Inverse Models– 20 models with TRANSCOM results

– 8 models with post-TRANSCOM results resolved to 1x1 degree

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TBM Model Net Flux for North America

Across model mean net flux; 2000-2005

NEP = 0.66 PgC/yr (1.8 to -0.25 PgC/yr)

NPP = 9.2 PgC/yr (6.2 to 13.8 Pg C/yr)

GPP = 18.4 PgC/yr (9.9 to 31.7 Pg C/yr)

Rh = 8.6 PgC/yr (5.8 to 13.1 Pg C/yr)

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Long-term Mean Summer (June, July, August) Net Ecosystem Productivity

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Can we diagnose the reasons for the lack of consensus in TBM performance?

Driver data

Photosynthesis formulation

Phenology

Decomposition – N limitation

Regional differences

Missing important processes

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Crossover Models - Regional model runs are more positively biased for GPP. Site model runs closer to observations.

Raczka et al. (in preparation)


Long-Term Mean NEE – TBMs and Inversions

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Net NPP over U.S. Agricultural Lands:Models Compared to NASS Inventory-Based Data

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Net NPP Spatial Pattern Over U.S. Agricultural Lands: Models Compared to NASS Inventory-Based Data

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Inventory – Model Comparison

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Data Sources Years of Data Location Fluxes and Pools Available Source

Canada Mgd. Forest (CBM-CFS3) 2000 – 2006 Canada (n = 15) NEE, NPP, VegC, Fire

EmissionsKurz et al.Stinson et al.

Canada Croplands 2000 – 2006 (average) Canada (n = 8) NEE, NPP McConkey

U.S. Forest (FIA / CCT) 2000 – 2006 Continental U.S. plus Alaska (n = 49) NEE, VegC Smith & Heath

U.S. Croplands 2000 – 2005 Continental U.S. (n = 49) NEE, NPP West et al.

Mexico 2000 - 2005 Mexico (n = 32) NEE, VegC, Fire Emissions deJong et al. 2010


Accounting for Lateral Fluxes

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CO 2

CO 2

Resid

ue

VEGC

SOILC

Harvest

LivestockC

CH4

HumanC

CH4

Consumption

Imports – Exports

Land Use Change

PRODC

Fir

e

RH

NP

P

Fir

e

NEE

Grasslands /

Settlements

CO

2 U

ptake

CO

2 R

elea

se

NEEForest / Cropland

Sector“Other” Lands Sector

Export


INV

EN

TO

RY

D

AT

A

TOTAL FORESTLAND CROPLAND OTHER LANDS

FO

RW

AR

D

MO

DE

LS

INV

ER

SE

M

OD

EL

S

Mean average annual NEE (Tg C yr-1), 2000 to 2006


Summary

Regional TBM comparisons indicate a lack of consensus for NEP and component fluxes – GPP, Ra, Rh

Analyses to diagnose the causes reveal:– Model formulation plays a significant role.

– Different weather driver data sets greatly impact GPP

TBM Re tends to be tightly related to GPP – this dampens the NEE seasonal cycle and IAV

Annual NEE cycle amplitude is small for TBM compared to inversions.

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Conclusions Regional C modeling enterprise needs a more rigorous

approach to development and evaluation.

Large disparities remain in estimates based on temporal and spatial extrapolations of experimental and site based understanding.

Additional data, especially based on spatially extensive measurements, needs to be integrated into the modeling system approach.– Improve model algorithms/parameters

– Improved diagnostic and predictive usefulness

– Evaluate model skill

– Develop useful benchmarks

An transition from data-poor to data-rich approach is emerging for developing multi-stream observing systems and modeling system analyses.

The NACP regional synthesis has contributed by exploring how a wider range of data sources can be used.

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Next Steps

RECCAP– If you have model results for 1990-2008 we would

be interested in incorporating them into the North American RECCAP chapter.

– Contact Mac Post <[email protected]>

MsTMIP– If you didn’t make it to the Side Meeting yesterday

you are still invited to participate

– Contact Deborah Huntzinger <[email protected]>

– Check the NACP web site for a MsTMIP e-mail list to be started soon.

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Acknowledgments

NASA Terrestrial Ecology support the Modeling and Synthesis Thematic Data Center (MAST-DC)

DOE Office of Science for workshop support

NOAA support for collecting inversion model results

Generous contributions of time and resources from any modeling teams and data providers that made these analyses possible

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managed by ut-battelle for the department of energy estimating the north american carbon balance...

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