Dust and sand lifted from the Saharan Desert can rise up in into the Earth’s atmosphere and travel thousands of miles across the Atlantic Ocean, reaching as far away as the United States and the Arctic. Atmospheric Saharan debris influences ecosystems, weather systems, and even air quality.
Why dust height matters
Understanding how high Saharan dust ascends in the atmosphere is important for assessing its impact on weather forecasting and climate modeling. Dust particles in the air can scatter and absorb sunlight, influencing atmospheric temperature profiles and cloud formation.
It’s not just the geographic extent of dust in the atmosphere that is important to understand for climate modeling. The vertical distribution of dust in the atmosphere affects how much of the Sun’s radiation is absorbed or reflected, known as the Earth’s “radiative balance”.
Limitations of active sensors in measuring atmospheric Saharan dust height
Historical remote sensing and LiDAR based measurements of vertical dust height have their limitations. Active sensors, like CALIPSO (Cloud-Aerosol Lidar and Infrared Pathfinder Satellite Observation) satellite and the International Space Station-based CATS (Cloud-Aerosol Transport System) are limited in their geographic scope and how frequently these sensors collect data. For example, researchers from NASA noted that CALIPSO was only able to measure 0.2% of the atmosphere in 2023.
Using passive remote sensing to measure atmospheric dust
A study published in Geophysical Research Letters looked at the reliability of using passive remote sensing onboard the deep space satellite DSCOVR (Deep Space Climate Observatory) . Researchers used four years of measurements from the Earth Polychromatic Imaging Camera (EPIC) to calculate the average monthly heights of Saharan dust clouds.
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Launched in 2015, DSCOVR orbits 1 million miles from Earth at the Lagrange-1 point (L1). L1 is the point between the Earth and the Sun where the gravitational pull of these two planetary bodies cancels out (known as the neutral gravity point). From this position, EPIC is able to remotely sense conditions in the atmosphere over the Atlantic Ocean every 1 to 2 hours.
Researchers from the University of Iowa extracted vertical dust conditions by developing an algorithm that analyzed data collected by EPIC’s oxygen A and B bands. Over a four year period (2015-2019) average vertical atmospheric dust measurements were collected for two separate seasons: the wet season (May–October) and the dry season (November–April). The study found that during the wet season, solar heating creates thermal buoyancy that lifts the dust higher in the atmosphere compared with the dry season.
Using both active and passive sensing to measure atmospheric dust
By contrast, two widely used models (MERRA-2 and NAAPS-RA) do not capture this daily pattern in dust height. These results suggest that EPIC’s multiple measurements each day could help refine atmospheric models so they can better represent how dust moves up and down in the atmosphere over the course of a day. Combining active and passive sensing can help researchers better understand how dust and other airborne particles vary over time.
References
Lu, Z., Wang, J., Chen, X., Zeng, J., Wang, Y., Xu, X., … & Xian, P. (2023). First mapping of monthly and diurnal climatology of Saharan dust layer height over the Atlantic Ocean from EPIC/DSCOVR in deep space. Geophysical Research Letters, 50(5), e2022GL102552.
Voiland, A. (2025, February 11). A daily boost in dust height. NASA Earth Observatory.
Xu, X., Wang, J., Wang, Y., Zeng, J., Torres, O., Yang, Y., … & Miller, S. (2017). Passive remote sensing of altitude and optical depth of dust plumes using the oxygen A and B bands: First results from EPIC/DSCOVR at Lagrange‐1 point. Geophysical Research Letters, 44(14), 7544-7554.
Fonte : National Geographic
