A model‐data intercomparison of CO2 exchange across North America: Results from the North American Carbon Program site synthesis - Schwalm, Christopher; Williams, Christopher; Schaefer, Kevin; Anderson, Ryan; Arain, M.; Baker, I.; Barr, Alan; Black, T.; Chen, Guangsheng; Chen, Jing; Ciais, Philippe; Davis, Kenneth; et al. (Journal of Geophysical Research: Biogeosciences, 2010)