This project brings together expertise in terrestrial boundary layer CO2 flux and mixing ratio observations and in high resolution land-atmosphere carbon cycle modeling. Methods will be developed for the fusion of CO2 data from disparate sources, including forward modeling driven by eddy-covariance flux measurements at the AmeriFlux sites and inverse modeling based on flask measurements of mixing ratio from the North American observational network for the time period 2004 – 2008. The forward and reverse modeling approaches will be cross-validated and reconciled with each other. The project aims to constrain the North American CO2 budget, show the seasonal and interannual variations correlated with drivers such as drought and compile a spatially and temporally explicit view of the North American carbon sink which can be compared against previous estimates based on ecological inventory methods. The final result from the project will be a comprehensive analysis system delivering monthly CO2 flux maps and associated uncertainty fields covering all of North America.