Modeled observations (prior, posterior, and synthetic) at two sample sites. Derived afternoon CO₂ enhancements are calculated using WRF-STILT footprints multiplied by prior, posterior, and (for synthetic data) “true” emissions. Results are shown for each measurement site with prior enhancements in blue, synthetic enhancements in black, and posterior in red. Synthetic and posterior observations are expressed as an average of an ensemble of 200 inversion runs, with the standard deviation of their observations shaded in gray and orange, respectively. September 19–2 and 27–29 are shown in dashed gray boxes to showcase abnormal behavior at the RPK site, when prior enhancements are higher than synthetic data values. DOI: https://doi.org/10.1525/elementa.375.f6