CIMSS Satellite Blog

Split Window Difference imagery over the Atlantic Basin, 1800 UTC 11 March through 1800 UTC 12 March 2019 (Click to animate)

A Saharan Air Layer (SAL) outbreak is occurring over the eastern Atlantic Ocean on 11-12 March 2019. The animation above shows the Split-Window Difference (10.3 µm – 12.3 µm) (link, from this website) color-enhanced to accentuate in red/pink/white the regions where Saharan Dust has been lofted into the atmosphere. This outbreak has been developing — this animation (courtesy Arunas Kuciauskas, NRL in Monterey) from 0400 UTC on 8 March to 1400 UTC on 11 March of the DEBRA product (Dust Enhancement with Background Reduction Algorithm, from this website) shows the dust originating west of a departing cyclone over northwest Africa).

NUCAPS Profiles sampled a region of the SAL on Tuesday 12 March, and those are shown below. (This has been discussed previously on this blog, here)  The swath of points is shown on top of a GOES-16 Red/Green/Blue image composite designed to highlight dust in pink. Sounding locations shown are denoted by the orange dot, and Precipitable Water associated with the sounding is indicated.  The accentuated mid-level drying associated with the SAL air, inferred by the pink in the RGB, is readily apparent.

GOES-16 Dust RGB at 1530 UTC on 12 March 2019 superimposed with NUCAPS sounding locations. Inset: NUCAPS Sounding in the location indicated by the orange dot. Total Precipitable Water for the sounding as indicated (Click to enlarge)

from CIMSS Satellite Blog http://cimss.ssec.wisc.edu/goes/blog/archives/32304