North American Carbon Program

1. Kevin Robert Gurney Colorado State University North American Carbon Program Scott Denning, Chair NACP Science Implementation Subcommittee US Carbon Cycle Science Steering Group

2. NACP Questions • What is the carbon balance of North America and adjacent oceans? What are the geographic patterns of fluxes of CO2, CH4, and CO? How is the balance changing over time? (“Diagnosis”) • What processes control the sources and sinks of CO2, CH4, and CO, and how do the controls change with time? (“Attribution/Processes”) • Are there potential surprises (could sources increase or sinks disappear)? (“Prediction”) • How can we enhance and manage long-lived carbon sinks ("sequestration"), and provide resources to support decision makers?(“Decision support”)

3. observingnetworks predictivemodels maps of variablefluxes and stocks experiments model/datafusion decisionsupport diagnosticmodels NACP Integration Strategy • Process studies and manipulative experiments inform improved models • Systematic observations used to evaluate models • Innovative model-data fusion techniques produce optimal estimates of time mean and spatial and temporal variations in fluxes and stocks • Improved models predict future variations,tested against ongoing diagnostic analyses • Predictive models and continuing analyses used to enhance decision support Scientific understanding Needs of stakeholders

4. Hierarchical Terrestrial Measurementsfor integration “Wall-to-wall” remote sensing and other spatial data…107 Extensive inventories (Forest and Cropland)………………..105 • More than 170,000 sites at 5-10 yr intervals • Complementary networks in Canada & Mexico Intermediate intensity sampling at many sites - facilitate scaling from local fluxes to regional modeling with RS/GIS (new)…………………………………………………………………..103 Very intensive investigation of processes……………………..102 ~ 100 flux towers, long-term ecological research sites, etc

5. Ocean Observations and Modeling • Coastal carbon burial and export to the open ocean • River-dominated margins and coastal upwelling regions merit special attention due to their dominant role in coastal carbon budgets • Coordination with US Ocean Carbon & Climate Change program

6. Atmospheric CO2 Observations ~2000

7. Atmospheric CO2 Observations ~2006

8. Orbiting Carbon Observatory(Planned August 2007 launch) • Estimated accuracy for single column ~1.6 ppmv • 1 x 1.5 km IFOV • 10 pixel wide swath • 105 minute polar orbit • 26º spacing in longitude between swaths • 16-day return time

9. Potential Satellite CO2 Observations • One day’s worth of column retrieval (Jul 2, no cloud mask) • Joint NIR/Thermal IR retrieval using both AIRS (2003) & OCO (2007) sensors

10. 1 Day of North American OCO Data • Three very narrow (10 km) swaths over N. America per day • Most of domain will be outside of strongest influence of observations • Spatial autocorrelation length scale? • Are tomorrow’s fluxes the same? • Need to handle temporal covariance

11. Air Parcel transport transport Sinks Air Parcel Air Parcel Sources Sample Sample Inverse Modeling concentration transport sources and sinks (model) (observe) (solve for)

12. Top-down Integrationusing atmospheric inverse models • Standard synthesis inversion using high-resolution transport and small regions tied to process characterization • Newer approaches using Lagrangian particle dispersion, adjoint transport, variational methods (e.g., 4DVAR), or Ensemble Kalman Filter (EnKF) • Combination of periodic large-scale constraint from airborne and flask sampling with continuous data • Inclusion of satellite data • Multi-gas inversions for source attribution

13. Capacity Building • TransCom community resources • Education • Code • Datasets • Control experiments http://transcom.colostate.edu; keving@atmos.colostate.edu

14. Spatially Distributed Process Modelingbottom-up integration • Models of terrestrial ecosystem fluxes, calibrated and tested against local data • “Slow” ecosystem dynamics: disturbance, succession, soil carbon biogeochemistry(Spatial mapping of carbon stocks) • Agroecosystem modeling (irrigation, fertilization, harvest, etc) • Coastal upwelling, air-sea fluxes, sedimentation • Fossil fuel emissions(new process-based approach)

15. Process-based Fossil Fuel CO2 Complementing the downscaling of fossil fuel sales/consumption information through surrogates…… ………Build from the history of the Air Quality effort • Emissions databases/models for regulated pollutants • CO, O3, NOx, SOx, particulates, Pb • Stack monitoring, geocoded, process-based • Long developmental history in the US Critical for bottom-up and top-down – Gurney et al., in press JGR Errors in “background” fields are aliased into target fluxes NASA funded project starting soon

16. “CONCEPT” Emissions Model • EMS undergoing fundamental updating to become “CONCEPT”, open-source based code (postgres SQL). • LADCO, ENVIRON, Applied Geophysics, UC Riverside • Combines inventory data and process attributes to construct detailed space and time dependent emissions of criteria pollutants. • Database/modelhas three classes of inputs: • Point sources – powerplants, for example • Mobile sources – vehicle emissions • Area sources – residential sources, for example • Resolution:36 km, hourly Modules Area source Point source Vehicle Biogenic nonroad

17. Model-Data Fusion(a.k.a. Data Assimilation) • Analogous to weather forecasting • Uses best process-based, deterministic models of key carbon fluxes and pools • Identification of key parameters that control uncertainty in final maps • Optimization of parameters according to all available observations (space and time) • Produces analyzed fields of fluxes and stocks that are optimally consistent with disparate observations and process understanding

18. Diagnostic Analysesoptimal process-based estimates at highest appropriate space/time resolution • Photosynthesis, respiration, decomposition • Combustion emissions (CO2, CO, CH4) including diurnal and weekly cycles • Storage of carbon in forests, grasslands, crops, fuel, rivers, reservoirs, estuaries, sediments • Transfers among pools • Net fluxes of CO2, CO, CH4 to the atmosphere • Finely resolved 3D grids of CO2, CO, CH4 in the atmosphere at hourly intervals

19. North American Carbon Budget(Gt C/year) Inverse • 1990s: TransCom3: -0.7 ± 0.5 (total uncertainty) Rodenbeck: -0.9 ± 0.2 • 1980s: TransCom3: -1.2 ± 0.5 Inventory • 1980s: Houghton: -0.15 to -0.35 (US) (direct) Pacala: -0.3 to -0.6 (US) (d and i) Birdsey: -0.31 (US) (forest) Remote Sensing • Myneni (1995 to 1999), -0.2 (woody bio only)

20. North American Interannual (T3) Gurney et al., in preparation

21. Convergence a IPCC estimates adjusted by Le Quere et al., 2003 b IPCC estimates adjusted by Plattner et al., 2002 c River transport corrected (0.6 Gt C/year) Gurney et al., in preparation

22. Thank you

23. NACP Intensive Field Campaigns • Motivation: evaluate integrated observing/modeling/assimilation system in a “testbed” for which all relevant variables are “oversampled” • Several IFCs may be required, to test various aspects of coupled analysis system • Crops & managed carbon fluxes with atmospheric sampling and inversion • Forest management, tiered sampling, biomass inventories • Combustion emissions inventory downscaling with detailed downwind trace gas measurements • Synoptic and cloud-scale meteorology and trace gas transport • Goal is a well-tested observing and analysis system with documented uncertainties that we understand

24. First NACP IFC • Mid-continent focus: 2005-2006 • Upper Midwestern United States • eastern South Dakota, eastern Nebraska, eastern Kansas, northern Missouri, Iowa, southern Minnesota, southern Wisconsin, and Illinois • Some elements of experiment may include larger or smaller areas • Reconcile estimates of sources and sinks derived from atmospheric models using measurements of trace gas concentrations with direct estimates based on field measurements, inventories, regional geographic information, and remote sensing • Attribution of sources and sinks to ecosystem processes and human activities within the region

25. Free Air Carbon Enrichment (FACE) • Fumigation rings maintain steady levels of elevated CO2 in canopies under changing weather conditions • Control and replicated treatments test effects of CO2, water, N, etc

26. FACE Sites • Many types of ecosystems around the world • Most only in place for a few years so far

27. Research Elements: Question 1Diagnosis of Current Carbon Budgets • A hierarchical approach for large-scale, distributed terrestrial measurements • Substantially improved fossil fuel emissions inventories with high resolution downscaling in time and space, and methods for evaluating these inventories using atmospheric measurements • Hydrologic transfers of carbon over land, and sequestration in sediments • Ocean measurements and modeling, both in the coastal zone and the open ocean, in coordination with the OCCC • An atmospheric observing system consisting of ground stations, aircraft and measurements from towers • Spatially-distributed modeling of carbon cycle processes • Model-data fusion and data assimilation to produce optimal estimates of spatial and temporal variations that are consistent with observations and process understanding • Interdisciplinary intensive field campaigns designed to evaluate major components of the model-data fusion framework

28. Research Elements: Question 2Processes Controlling Carbon Budgets • Terrestrial carbon response to changes in atmospheric CO2, tropospheric ozone, nitrogen deposition, and climate • Responses of terrestrial ecosystems to changes in disturbance regimes, forest management, and land use • Responses of terrestrial ecosystems to agricultural and range management • The impacts of lateral flows of carbon in surface water from land to fresh water and to coastal ocean environments • Estuarine biogeochemical transformations; • Coastal marine ecology and sedimentation; • Air-sea exchange and marine carbon transport; and • Human institutions and economics: use this research and modeling, or develop new research in this element? • Clearly acknowledge different approaches: manipulation vs inference from timeseries

29. Program Elements: Question 3Predictive Modeling • Transfer of synthesized information from process studies into prognostic carbon-cycle models • Retrospective analyses to evaluate the spatial and temporal dynamics of disturbance regimes simulated by prognostic models • Evaluation of predictions of interannual variations with predictive models against continued monitoring using observational networks and diagnostic model-data fusion systems • Development of scenarios of future changes in driving variables of prognostic models • Application and comparison of prognostic models to evaluate the sensitivity of carbon storage into the future • Incorporation of prognostic models into coupled models of the climate system

30. Program Elements: Question 4Decision Support • North American contribution to the State of the Carbon Cycle Report (SOCCR) • Analysis of the longevity of sinks • Assessment of sequestration options given best scientific evaluation of present and future behavior of carbon cycling • Provide scientific understanding to inform management of the carbon cycle given improved understanding, diagnosis, and prediction • Early detection of carbon cycle risks and vulnerabilities • Scenario development for simulation of future climate

31. Atmospheric Observing System • Existing global flask network provides seasonal/latitude background • Outer “ring” of buoy-based and airborne sampling documents variations in continental inflow and outflow • Continuous analyzers on tall towers • Continental airborne sampling 2x/week • Calibrated [CO2] at flux towers (VTT) • Satellite [CO2], [CO] , and [CH4] • Upward-looking FTIR spectrometers NACP Question 1: Diagnosis of current carbon budgets

32. NACP Atmospheric [CO2] Network

33. Atmospheric Modeling • Propagation of surface fluxes of CO2, CO, and CH4 estimated by from data using process-based models into atmosphere • Realistic transport at high resolution • Detailed comparison to atmospheric observations • Evaluation of mismatches, attribution of error to process characterization • Relationship of high-res efforts over NA to global obs and models NACP Question 1: Diagnosis of current carbon budgets

34. Important Gapsfor bottom-up scaling • High-resolution weather data to drive daily GPP and respiration calculations at native resolution of imagery and other spatial data • current 1 km MODIS products use 1-degree weather! • Historic land-use/land management data to drive calculations of carbon storage due to successional changes • Carbon flux and storage data for urban/suburban landscapes • Irrigation quantified in space and time? NACP Question 1: Diagnosis of current carbon budgets

35. Important Gapsfor Top-Down Scaling and Model-data fusion • Very high resolution meteorological drivers for tracer transport modeling • NCEP analyses currently ~2.5º at 6 hr intervals • Eta analyses higher resolution but limited area • Lateral boundaries • Mass conservation • Near-surface processes (e.g., PBL turbulence) • Cloud transports • Applied mathematics for assimilation into coupled models of carbon processes • Computational needs

36. atmosphere ocean forests farms cities industry ocean foresters farmers citizens industrialists economics institutions policy Sources, Sinks, and Processes • Carbon exchanges with the atmosphere over North America are managed by people • Understanding and predicting these exchanges will require quantification of management effects