managed by ut-battelle for the department of energy north american carbon balance – results from...

Managed by UT-Battellefor the Department of Energy

North American Carbon Balance – Results from the

Regional Synthesis Project

of the North America Carbon

Program 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

Identification of Sources/Sinks (regional)

– What are the magnitudes and spatial distribution of carbon sources and sinks, and their uncertainties during 2000-2005?

Characterize Interannual Variation (regional)

– What is the spatial pattern and magnitude of interannual variation in carbon fluxes during 2000-2005?

– What are the components of carbon fluxes and pools that contribute to this variation?

– Do model results and observations show consistent spatial patterns in response to interannual climate variation?

At intensively studied sites (flux towers)

– Are the various observations and modeling estimates of carbon fluxes at individual sites consistent with each other - and if not, why?

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

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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 NEE – TBMs and Inversions

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

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Net NPP Satial 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, FE Kurz 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 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 from developing integrated observing systems and model analyses.

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

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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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