New information is needed about the potential sources and pathways of trans-Atlantic dust plumes. Such knowledge has important implications for the long-distance transport and survivability of microorganisms. Forward trajectories of trans-Atlantic dust plumes were studied over a 14-year period, between 2008 and 2021 (n =>500,000 trajectories). Two major dust transport patterns emerged from these analyses. First, summer trajectories (June – August) that arrive in the southeastern regions of the United States and the Caribbean basin and travel above the marine boundary layer at an average altitude of 1,600 m. Second, winter trajectories (December – February) that arrive in the Amazon basin and travel within the boundary layer at an average altitude of 660 m. Ambient meteorological conditions such as solar radiation and relative humidity along dust trajectories suggest a more suitable condition for the survivability of microorganisms reaching the Amazon during the winter with a lower mean solar radiation flux of 294 W m-2 and mean relative humidity levels at around 61% as compared to averages of 370 W m-2 solar radiation and 45% relative humidity for summer trajectories intruding the Caribbean basin. Nevertheless, 14% of winter trajectories (4,664 out of 32,352) reaching the Amazon basin face intense precipitation of higher than 30 mm and get potentially removed as compared to 8% of trajectories (2,540 out of 31,826) intruding the Caribbean basin during the summer. Collectively, our results have important implications for the survivability of microorganisms in trans-Atlantic dust plumes and their potential for major incursion events at receptor regions.
