Long-Term Seasonal Trends in Sources and Pathways of Trans-Atlantic Dust
Plumes and their Implications for Transport of Microorganisms
Abstract
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.