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Offshore transport of glacial silt from Southeast Alaska

By Scott Bachmeier •

GOES-17 CIMSS Natural Color RGB images [click to play animation | MP4]

GOES-17 CIMSS Natural Color RGB images [click to play animation | MP4]

GOES-17 (GOES-West) CIMSS Natural Color RGB images (above) depicted a large offshore surge of airborne glacial silt from Southeast Alaska on 25 April 2021. During the preceding week, abnormally warm and dry conditions across much of Southeast Alaska (Juneau | Ketchikan | Sitka | Yakutat) promoted significant snow melt which exposed a great deal of surface glacial silt.

The leading edge of the aerosol could also be seen in GOES-17 Near-Infrared “Cirrus” (1.37 µm) images (below). The presence of a very dry air mass over the region (rawinsonde data: Yakutat | Annette Island) allowed some of the lower-tropospheric aerosol to be sensed by this spectral band.

GOES-17 Near-Infrared "Cirrus" (1.37 µm) images [click to play animation | MP4]

GOES-17 Near-Infrared “Cirrus” (1.37 µm) images [click to play animation | MP4]

GOES-17 True Color RGB images created using Geo2Grid (below) provided a clearer view of the areal coverage of glacial silt moving westward off the coast.

GOES-17 True Color RGB images [click to play animation | MP4]

GOES-17 True Color RGB images [click to play animation | MP4]

With ample illumination from the Moon (which was in the Waxing Gibbous phase, at 96% of Full),  the emergence of airborne particles off the Southeast Alaska coast was seen in a Suomi NPP VIIRS Day/Night Band (0.7 µm) image at 1221 UTC (below).

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) image [click to enlarge]

Categories: GOES-17, Red-Green-Blue (RGB) images, Suomi NPP, VIIRS