170 likes | 192 Views
North American Carbon Balance – Results from the Regional Synthesis Project of the North America Carbon Program.
E N D
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
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? Presentation_name
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 Presentation_name
Long-term Mean Summer (June, July, August) Net Ecosystem Productivity Presentation_name
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) Presentation_name
Long-Term Mean NEE – TBMs and Inversions Presentation_name
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 Presentation_name
Net NPP over U.S. Agricultural Lands:Models Compared to NASS Inventory-Based Data Presentation_name
Net NPP Satial Pattern Over U.S. Agricultural Lands: Models Compared to NASS Inventory-Based Data Presentation_name
Inventory – Model Comparison Presentation_name
Forest / Cropland Sector “Other” Lands Sector Accounting for Lateral Fluxes NEE NEE CH4 CH4 CO2 CO2 RH NPP Fire Fire DLivestockC DHumanC Consumption Harvest DVEGC DPRODC CO2 Release CO2 Uptake Residue Grasslands / Settlements DSOILC Imports – Exports Export Land Use Change Presentation_name
TOTAL FORESTLAND CROPLAND OTHER LANDS INVENTORY DATA FORWARD MODELS INVERSE MODELS 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. Presentation_name
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. Presentation_name
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 Presentation_name