The space and time impacts on U.S. regional atmospheric CO₂ concentrations from a high resolution fossil fuel CO₂ emissions inventory

To improve fossil fuel CO₂ emissions estimates, high spatial and temporal resolution inventories are replacing coarse resolution, annual-mean estimates distributed by population density. Because altering the emissions changes a key boundary condition to inverse-estimated CO₂ fluxes, it is essential to analyse the atmospheric impacts of redistributing anthropogenic emissions. Using a coupled ecosystem-atmosphere model, we compare 2004 atmospheric CO₂ concentrations resulting from coarse and high-resolution inventories. Using fossil fuel CO₂ emissions inventories with coarse spatial and temporal resolution creates spatially coherent biases in the atmospheric CO₂ concentrations. The largest changes occur from using seasonally varying emissions: in heavily populated areas along the west coast and the eastern United States, the amplitude of the near-surface CO₂ concentration seasonal cycle changed by >10 ppm, with higher concentrations in summer and lower concentrations in fall. Due to changes in the spatial distribution, spatially coherent annual mean concentration differences >6 ppm occur; and including the diurnal cycle causes changes >3 ppm. To avoid significant errors in CO₂ source and sink estimates from atmospheric inversions, it is essential to include seasonality in fossil fuel emissions, as well as to utilize higher-resolution, process-based spatial distributions.