Fig. 1: Geographic distribution of the individual measurements considered in this study, separated by instrument type.
From: Mass absorption cross-section of ambient black carbon aerosols - a review

MAAP photometers were distinguished from other filter-based absorption photometers due to their difference in working principle. Highlighted countries correspond to studies wherein data were compiled from multiple locations into a single value for the MAC or aircraft-based campaigns covering a broader region. Background color scale shows the BC column mass concentration between 2022 and 2024 from a data assimilation model194.