PyroCb in northern Alberta, Canada

GOES-13 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click to play animation)

GOES-13 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click to play animation)

Kudos to Mark Ruminski (NOAA/NESDIS Satellite Analysis Branch) for spotting this pyroCB event in far northern Alberta, Canada late in the day on 14 June 2014. McIDAS images of GOES-13 1-km resolution 0.63 µm visible channel (left panels) and GOES-13 4-km resolution 3.9 µm shortwave IR channel (right panels) data (above; click image to play animation; also available as an MP4 movie file) showed the initial subtle signal of a fire “hot spot” at 19:30 UTC (exhibiting an IR brightness temperature 293.1 K), whose temperature increased rapidly to 320.6 K at 19:37 UTC. By 21:55 UTC, the maximum IR brightness temperature of the fire hot spot was 337.7 K.

A 4-panel comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) visible and shortwave IR images (below; click image to play animation; also available as an MP4 movie file) indicated that with the more favorable western view angle from GOES-15, the fire hot spot was able to be detected at an earlier time (18:30 UTC), and also at a number of later times when the hot spot was obscured from the view of GOES-13 by dense pyroCb clouds.

GOES-15 (left panels) and GOES-13 (right panels) visible and shortwave IR channel images (click to play animation)

GOES-15 (left panels) and GOES-13 (right panels) visible and shortwave IR channel images (click to play animation)

An AWIPS image comparison of 1-km resolution Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel data at 20:51 UTC (below) showed the initial plume of pyroCb clouds drifting northeastward from the fire source (which actually showed up as a hot, dark black cluster of pixels, even on the longwave IR image). The coldest IR brightness temperature of the pyroCb cloud at that time was -53º C.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

A 1-km resolution NOAA-18 AVHRR 10.8 µm IR channel image at 23:11 UTC (below) also showed a minimum IR brightness temperature of -53º C for the pyroCb cloud.

NOAA-18 AVHRR 10.8 µm IR channel image

NOAA-18 AVHRR 10.8 µm IR channel image

The initial northwestward drift of the pyroCb cloud followed by a southwestward drift of the pyroCb cloud is explained by the change in wind direction with height, as seen on a nearby rawinsonde profile from Fort Smith, Northwest Territories (below). According to this sounding, the tropopause was at a height of 10.6 km, where the air temperature was -60º C.

Fort Smith, Northwest Territories rawinsonde profile

Fort Smith, Northwest Territories rawinsonde profile

The fire complex continued to burn into the night; a VIIRS 3.74 µm shortwave IR image at 10:36 UTC on 15 June (below) showed the cluster of fire hot spots (black pixels).

Suomi NPP VIIRS 3.74 µm shortwave IR image

Suomi NPP VIIRS 3.74 µm shortwave IR image

The Suomi NPP OMPS Aerosol Index (below; courtesy of Colin Seftor) showed the signature of fire smoke on 15 June, with a maximum AI value of 5.2.

Suomi NPP OMPS Aerosol Index product

Suomi NPP OMPS Aerosol Index product

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