PyroCbs in British Columbia

Early on 12 August 2017 two pyroCbs formed in British Columbia, Canada. GOES-15 detected the smoke plume and pyroCb cloud, as well as the fire hot spots. The first pyroCb cloud (near 51.8º N, 123.2ºW) developed around 03:30 UTC . The second formed about 1.5 hours later, at 05:00 UTC (near 53.1º N,  121ºE). Starting at 03:00 UTC on 12 August, the animation below shows GOES-15 10.7 µm IR (left) and 3.9 µm shortwave IR (right). In the shortwave IR images, the darker black pixels indicate very hot IR brightness temperatures exhibited by the fire source regions. Since these pyroCbs formed after sunset, visible imagery was not available.

Using GOES-15 10.7 μm IR channel imagery, the cloud-top IR brightness temperature could be determined. The animation below shows the brightness temperature for the first pyroCb cloud reaching near -30ºC at 04:00 UTC (dark blue color enhancement). The second pyroCb reached -38ºC  at 05:30 UTC (green color enhancement). Even though from GOES-15 imagery these pyroCbs did not reach the -40ºC pyroCb threshold, higher spatial resolution GOES-16 imagery (not shown) indicated that both of these pyroCbs exhibited cloud-top IR brightness temperatures as cold as -42ºC .

GOES-15 20.7 µm IR channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

GOES-15 10.7 µm IR channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

=====  12 August Update =====

Later in the evening on 12 August, 3 additional pyroCb clouds developed from the ongoing intense BC fires. A toggle between NOAA-18 Visible (0.63 and 0.86 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.3 µm) images is shown below.

NOAA-18 Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.3 µm) images, with surface station plots in yellow [click to enlarge]

NOAA-18 Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Longwave Infrared Window (10.3 µm) images, with surface station plots in yellow [click to enlarge]

A daytime Suomi NPP VIIRS true-color image is shown below, with VIIRS-detected fire locations plotted in red — a very large pall of exceptionally-dense smoke from the BC fires could be seen drifting northward as far as the Northwest Territories of Canada.

Suomi NPP VIIRS true-color image, with VIIRS-detected fire locations plotted in red [click to enlarge]

Suomi NPP VIIRS true-color image, with VIIRS-detected fire locations plotted in red [click to enlarge]

The Suomi NPP OMPS Aerosol Index product (below; courtesey of Colin Seftor) displayed AI values as high as 17.18.

Suomi NPP OMPS Aerosol Index [click to enlarge]

Suomi NPP OMPS Aerosol Index [click to enlarge]

===== 13 August Update =====

Suomi NPP OMPS Aerosol Index product [click to enlarge]

Suomi NPP OMPS Aerosol Index product [click to enlarge]

On 13 August, a maximum OMPS AI value of 39.91 was seen at around 21:13 UTC over the Northwest Territories of Canada (above) — according to Colin Seftor and Mike Fromm, this value surpassed the highest pyroCb-related AI value measured by TOMS or OMI (whose period of record began in 1979).

The north-northeastward transport of BC fire smoke — as well as a prominent increase in smoke from fires in northern Canada and the Prairies — was evident in an animation of daily composites of Suomi NPP VIIRS true-color images from 07-13 August (below).

Daily Suomi NPP VIIRS true-color image composites (07-13 August), with VIIRS-detected fire locations plotted in red [click to play animation]

Daily Suomi NPP VIIRS true-color image composites (07-13 August), with VIIRS-detected fire locations plotted in red [click to play animation]

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