Figure S4. Surface flux drivers of observed tracer-tracer correlations in ACT-America South region in Summer 2016. This is similar to Figure 8 in the main text with the following exceptions (1) map of ACT flask samples is removed, (2) the salt marsh experiment is excluded, (3) the biogenic CO2 flux perturbation is excluded, and (4) an additional perturbation experiment for biogenic CO flux is included. For (3), we decrease biogenic CO flux by a factor of 2 in the south, which is denoted as “Posterior CO: Biogenic * 0.5” in several of the subplot titles.