Atmospheric Variations in Summertime Column Integrated CO2 on Synoptic Scales Over the US

Past studies have demonstrated that synoptically active weather systems play an important role in the spatial and temporal variations of atmospheric carbon dioxide (CO2) within and above the planetary boundary layer. For the first time, we investigate the spatial variability of column-averaged dry-air mole fractions of CO2 (i.e., XCO2) due to the impact of synoptic scale transport using retrievals from the Orbiting Carbon Observatory-2 (OCO-2) for 66 summer cold front passage cases over the conterminous U.S. and Mexico from 2015 to 2019. XCO2 differences across cold fronts in summer were found to be in good agreement with observations obtained from the Atmospheric Carbon and Transport (ACT-America) field campaign, though with a reduced magnitude due the flat averaging kernel representing fairly uniform vertical sensitivity in the troposphere as opposed to in situ CO2 measurements. OCO-2 observed XCO2 frontal differences are statistically distinct from north-south XCO2 climatological spatial variations on similar spatial-scales on synoptically benign days, implying that the frontal passages contribute to enhanced XCO2 spatial contrasts. An exploratory analysis finds no evidence of a linkage between the temperature differences and XCO2 differences, but a more thorough exploration is left as future work.