CIMSS Satellite Blog

Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images, with topography [click to enlarge]

In a comparison of Suomi NPP VIIRS Visible (0.64 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images on 12 May 2019 (above), a dark grey volcanic ash fall streak was evident in the Visible image, which extended over 100 miles southward from the Shilevuch volcano on the Kamchatka Peninsula of Russia. This feature was a layer of volcanic ash that had been deposited on top of existing snow cover — note that most of the dark ash fall steak exhibited much cooler infrared brightness temperatures than the bare ground of the interior valley to the west.

This ash fall streak was a result of an explosive eruption of the volcano over a month earlier, on 10 April — the volcanic ash plume could be seen moving southward in Himawari-8 Visible (0.64 µm) images (below).

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

An interesting aspect of this long-lived ash fall streak was that a portion of it was apparently covered by a layer of fresh snowfall at some point after the eruption — and a 7-day sequence of Suomi NPP VIIRS True Color Red-Green-Blue (RGB) images viewed using RealEarth (below) suggested that this layer of new snow was melting with the aid of the high May sun angle, gradually revealing more of the original length of the ash fall streak.

Suomi NPP VIIRS True Color RGB images, 06-12 May 2019 [click to play animation | MP4]

Note that there was another volcanic plume moving south-southwestwarrd from Shiveluch in the 09 May VIIRS True Color image — retrieved quantities of ash probability, height, loading and effective radius for this volcanic plume (source) are shown below.

Suomi NPP False Color, Ash Probability, Height, Loading and Effective Radius [click to enlarge]

This type of volcanic ash fall streak frequently occurs on the snow-covered Kamchatka Peninsula — here is an example from March 2013.

Thanks go out to Santiago Gassó for bringing this interesting feature to our attention.

In #Kamchatka today, this feature caught my attention. A long dark streak , it is not atmospheric, it appears lack of snow on the ground, it is there the previous days. I am not super familiar with the topo but I do not recall seeing it before. Any guess? some ground heating? pic.twitter.com/ShVbWCPJhF

— Santiago Gassó (@SanGasso) May 12, 2019

from CIMSS Satellite Blog http://cimss.ssec.wisc.edu/goes/blog/archives/33196