PyroCb in northern Alberta, Canada

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)

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

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

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

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

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