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Stratus clouds affecting surface temperatures in Alaska

By Scott Bachmeier •

GOES-17 Nighttime Microphysics RGB and

GOES-17 Nighttime Microphysics RGB and “Clean” Infrared Window (10.35 µm) images [click to play animation | MP4]

A comparison of GOES-17 (GOES-West) Nighttime Microphysics RGB and “Clean” Infrared Window (10.35 µm) images (above) showed the formation and motion of patchy stratus clouds (RGB shades of yellow) over Interior Alaska on 17 December 2019.  Note how the clouds are difficult to detect and track on the 10.35 µm images, since the temperatures of cold land surfaces and stratus cloud tops were similar. Since these high latitudes receive little to no sufficient solar illumination to allow useful visible imagery during the winter season, the RGB product can be a helpful tool for monitoring the evolution of such low clouds.

Plots of surface data from Bettles (PABT) and Fort Yukon (PFYU) (below) showed that the stratus cloud deck — with bases in the 6,000-10,000 feet range — had an impact on surface air temperature trends, with warming occurring as radiational cooling was slowed and/or reversed as the clouds moved overhead. Temperatures continued to rise at Bettles as the cloud coverage remained broken to overcast, while the temperature briefly dropped again at Fort Yukon as the cloud coverage thinned to scattered.

Plot of surface data from Bettles, Alaska [click to enlarge]

Plot of surface data from Bettles, Alaska (PABT) [click to enlarge]

Plot of surface data from Fort Yukon, Alaska [click to enlarge]

Plot of surface data from Fort Yukon, Alaska (PFYU) [click to enlarge]

Categories: Arctic, GOES-17, Red-Green-Blue (RGB) images