PyroCb with the Little Bobtail Lake Fire in British Columbia

GOES-15 0.63 µm visible (left) and 3.9 µm shortwave IR (right) images (click to play animation)

The first verified pyrocumulonimbus (pyroCb) cloud of the 2015 wildfire season formed in central British Columbia, Canada late in the day on 12 May 2015. A comparison of GOES-15 (GOES-West) 0.63 µm visible and 3.9 µm shortwave IR images (above; click image to play animation; also available as an MP4 movie file) showed the growth in areal coverage of smoke starting at 1800 UTC, as the fire began to exhibit very hot shortwave IR brightness temperatures (red pixels).

A comparison of 2156 UTC Suomi NPP VIIRS 3.74 µm shortwave IR and true-color Red/Green/Blue (RGB) images visualized using the SSEC RealEarth web map server (below) showed a closer view of the fire hot spot (dark black pixels on the shortwave IR) just southwest of Prince George, and the smoke plume which was drifting to the northwest.

Suomi NPP VIIRS 3.74 µm shortwave IR and true-color RGB images

http://www-calipso.larc.nasa.gov/data/BROWSE/production/V3-30/2015-05-12/2015-05-12_20-38-38_V3.30_3_6.png

———————————————————————————————

POES AVHRR Cloud Top Temperature product

Robust pyrocumulus cloud production began around 23 UTC, with a CLAVR-x POES AVHRR Cloud Top Temperature product depicting a pyroCb cloud with a minimum temperate of -59º C, and a maximum Cloud Top Height value of 9 km at 2352 UTC. Less than an hour later, the 01:33 UTC POES AVHRR Cloud Top Temperature product (above) again showed a minimum value of -59º C (darker red color enhancement), with the corresponding Cloud Top Height product (below) indicating a maximum of 11 km (darker green color enhancement) for the pyroCb cloud northwest of Prince George (station identifier CYXS).

POES AVHRR Cloud Top Height product

The GOES-15 3.9 µm shortwave IR imagery above showed that the fire continued to burn through the night, with a flare-up of hot pixels from 06 to 11 UTC. During this nocturnal flare-up, a 1013 UTC Suomi NPP VIIIRS 0.7 µm Day/Night Band image showed the large and very bright glow associated with the active fire, which also exhibited a large “hot spot” (black to yellow to red pixels) on the 3.74 µm shortwave IR image (below).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

—– 13 May Update —–

Suomi NPP VIIRS 3.74 µm shortwave IR, 0.65 µm visible, and 0.7 µm Day/Night Band images

On 13 May, a toggle between Suomi NPP VIIRS 3.74 µm shortwave IR, 0.65 µm visible, and 0.7 µm Day/Night Band images at 1956 UTC (above) showed that the bulk of the wildfire smoke had drifted westward toward the coast of British Columbia, and then northward at least as far as the Juneau, Alaska (station identifier PAJN) area. This smoke transport was verified by Suomi NPP OMPS Aerosol Index data, courtesy of Colin Seftor (below). The maximum AI value of 8.5 was located at 57.55º N latitude, 134.61º W longitude at 2147 UTC.

OMPS Aerosol Index

A CALIPSO overpass caught the western edge of the OMPS aerosol plume, with CALIOP lidar total attenuated backscatter indicating the presence of smoke aloft at altitudes as high as 5.5 and 10.5 km (below); for more details, see this analysis courtesy of Mike Fromm.

CALIPSP CALIOP lidar total attenuated backscatter

—– 14 May Update —–

On 14 May, a toggle between Suomi NPP VIIRS true-color Red/Green/Blue (RGB) and 3.74 µm shortwave IR images at 2117 UTC (below) showed that the smoke had begun drifting to the south.

Suomi NPP VIIRS true-color RGB and 3.74 µm shortwave IR images

Furthermore, CALIPSO LIDAR can be used to help further investigate the transport of smoke from the wildfire. This LIDAR shows the height of the clouds produced by the fire. The first image is the 532 nm Total Attenuated Backscatter plot on 12 May from 21:05 UTC to 21:19 UTC. The smoke from this fire can be seen around 60 N, indicated on this plot by light grey/white pixels. The area with smoke is conclusive the the fire that produced the pyroCb. The next image is the Depolarization plot, on this plot the smoke is indicated by orange pixels. The third image is the 1064 nm Total Attenuated Backscatter plot, the smoke on this plot is indicated by a light grey color. The fourth image is the Attenuated Ratio plot between 1064 nm and 532 nm. The smoke is indicated by teal and purple pixels. The fifth image is the Vertical Feature Mask. This plot shows the different features that are in the atmosphere, the smoke is attributed as a cloud on this plot and is indicated by a light blue color. The last image shows the different subtypes of aerosols that are detected by the LIDAR. On this plot the smoke can be seen as a column around 60 N (indicated by a black color) showing that this is spot of fire.