Sensitivity of simulated COsub2/sub concentration to sub-annual variations in fossil fuel COsub2/sub emissions

摘要

pstrongAbstract./strong Recent advances in fossil fuel COsub2/sub (FFCOsub2/sub) emission inventories enable sensitivity tests of simulated atmospheric COsub2/sub concentrations to sub-annual variations in FFCOsub2/sub emissions and what this implies for the interpretation of observed COsub2/sub. Six experiments are conducted to investigate the potential impact of three cycles of FFCOsub2/sub emission variability (diurnal, weekly and monthly) using a global tracer transport model. Results show an annual FFCOsub2/sub rectification varying from −1.35 to +0.13 ppm from the combination of all three cycles. This rectification is driven by a large negative diurnal FFCOsub2/sub rectification due to the covariation of diurnal FFCOsub2/sub emissions and diurnal vertical mixing, as well as a smaller positive seasonal FFCOsub2/sub rectification driven by the covariation of monthly FFCOsub2/sub emissions and monthly atmospheric transport. The diurnal FFCOsub2/sub emissions are responsible for a diurnal FFCOsub2/sub concentration amplitude of up to 9.12 ppm at the grid cell scale. Similarly, the monthly FFCOsub2/sub emissions are responsible for a simulated seasonal COsub2/sub amplitude of up to 6.11 ppm at the grid cell scale. The impact of the diurnal FFCOsub2/sub emissions, when only sampled in the local afternoon, is also important, causing an increase of +1.13 ppmv at the grid cell scale. The simulated COsub2/sub concentration impacts from the diurnally and seasonally varying FFCOsub2/sub emissions are centered over large source regions in the Northern Hemisphere, extending to downwind regions. This study demonstrates the influence of sub-annual variations in FFCOsub2/sub emissions on simulated COsub2/sub concentration and suggests that inversion studies must take account of these variations in the affected regions./p.