Transport of Saharan Air Layer dust across the Atlantic
The GOES-16 (GOES-East) Saharan Air Layer (SAL) infrared Split Window (12.3 µm – 10.3 µm) product (above) showed a large outbreak of SAL dust that emerged from the northwest coast of Africa on 30 July 2018, eventually moving over the Lesser Antilles and Puerto Rico late in the day on 03 August.During daylight hours, the dust-laden SAL was also evident in GOES-16 Natural Color Red-Green-Blue (RGB) imagery (source) on 01, 02 and 03 August (below).
The AWIPS version of GOES-16 Split Window (10.3 µm – 12.3 µm) imagery with a different color enhancement (above) showed the westward motion of the SAL dust (shades of cyan) on 02 August. The corresponding GOES-16 Dust Detection product (below) verified the presence of dust within the SAL plume. Since the Dust Detection product uses Visible and Near-Infrared bands, it is only available during daytime hours (and at solar zenith angles less than 60 degrees). GOES-16 Split Window (10.3 µm – 12.3 µm) imagery from 03 August (above) showed the continued westward motion of the SAL dust (shades of cyan). The corresponding GOES-16 Aerosol Optical Depth (AOD) product (below) provided a more quantitative measure of airborne dust. Like the Dust Detection product shown previously, the AOD product also uses Visible and Near-Infrared bands — so it too is only available during daytime hours (and at solar zenith angles less than 60 degrees). Additional information on GOES-R Aerosol Detection Products in AWIPS is available here and here. The 03 August GOES-16 imagery indicated that the leading edge of the SAL began to move over Puerto Rico late in the day. A comparison of morning and evening rawinsonde data from San Juan (below) revealed that the temperature inversion at the base of the SAL became more well-defined at 00 UTC on 04 August.