A potent upper level low pressure system traversed across northern Africa on 12 March 2020, causing the development of strong winds at the surface. Water Vapor imagery from EUMETSAT Meteosat-8 shows the compact low advancing east across Egypt on the 12th, with gravity waves emanating southward across bordering countries (Fig 1).
Figure 1: 12 March 2020 EUMETSAT Meteosat-8 6.2 um water vapor imagery. Higher res
The windy conditions at the surface resulted in a broad area of blowing dust across much of the northern half of the continent. The EUMETSAT Meteosat-8 satellite captured the lofted dust as it was carried south and west away from the low and over a long distance. The thick layer of lofted dust was captured well in both the 0.6 um VIS (Fig 2) and 10.8 um IR Window (Fig 3) single-band imagery.
Figure 2: 12 March 2020 EUMETSAT Meteosat-8 0.6 um visible imagery. Dust is represented by relatively higher reflectance values, or lighter gray values compared to the bare surface. Higher resFigure 3: 12 March 2020 EUMETSAT Meteosat-8 10.8 um IR imagery. Dust is represented by the cooler brightness temperatures, or lighter gray values compared to the bare surface. Higher res
Combining multiple bands to make multispectral imagery allowed for similar detection of dust across Africa. The dust was diagnosed in the split window difference and IR Window image combo, Geocolor, and Dust RGB imagery.
Figure 4: 12 March 2020 EUMETSAT Meteosat-8 10.8 minus 12.0 um split window difference imagery. Negative values, or darker grays and blacks, represent lofted dust. Colors are cold IR brightness temperatures, or clouds. Higher resFigure 5: 12 March 2020 EUMETSAT Meteosat-8 Geocolor imagery from CIRA. Higher resFigure 6: 12 March 2020 EUMETSAT Meteosat-8 Dust RGB imagery. Dust is represented by the varying shades of Magenta across the scene. Higher res
A closer look at region of optically thick blowing dust across Sudan is provided in Figure 7.
Figure 7: 12 March 2020 EUMETSAT Meteosat-8 0.6 um visible imagery (zoomed in to Sudan). Dust is represented by relatively higher reflectance values, or lighter gray values compared to the bare surface. Higher res
