Fig. 3: Quantification of African & South American black carbon mass concentrations.

Relative (a) and absolute (b) contributions of African vs South American biomass burning to total rBC mass concentration at ATTO in 2019 and 2020. c The colored bar code represents five flags for dominant and majoritarian South American influence, dominant and majoritarian African influence, as well as pristine aerosol conditions, which is the basis for the classification of smoke properties in Fig. 4. d As proxy for periods with intense South American smoke influence: cumulative number of fires, CF_BT, along the 3-day BTs starting at 200 m at ATTO³⁰; e As proxy for African smoke influx into the Amazon: satellite-derived carbon monoxide (CO) concentration in an offshore region of interest off the Brazilian coast (ROI_offshore); f As proxy for aerosol wet scavenging in air masses arriving at ATTO: cumulative precipitation, P_BT, along the 3-day BTs²⁴. The Amazonian seasonality is shown as colored bars on top of the time series for reference, which has been defined and used in previous studies^{8,24,25,33,44,75} as follows: wet season (February to May), dry season (August to November), and transition periods (June-July and December-January).