Possible PyroCb in Australia

On 07 December there was a possible pyroCb in the southern coast of western Australia. Himawari-8 monitored the temporal evolution of the smoke plumes and pyroCb cloud, as well as the fire hot spots. Starting at 0:00 UTC on 07 December, the animation below (also available as an MP4) shows Himawari-8 0.63 µm visible (left) and 3.9 µm shortwave IR (right) . The possible pyroCb cloud (~32.1º S, 126.1ºE) formed around 2:00 UTC. In the shortwave IR images, the red pixels indicate very hot IR brightness temperatures exhibited by the fire source regions.

Himawari-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

Himawari-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

In addition, the Himawari-8 10.4 μm IR channel allowed the cloud-top IR brightness temperature to be measured. This provided some insight into whether this was pyroCb or just a pyroCu. The animation below, also starting at 1:00 UTC on 07 December, shows that the brightness temperature coming from the fire to be rather low (white color enhancement). Once the pyroCu from the fire interacts with other convection then the brightness temperatures decrease. It is hard to say if the pyroCu transformed into a pyroCb or if the clouds interacted with convection.

Himawari-8 10.4 µm IR channel images (click to play animation)

Himawari-8 10.4 µm IR channel images (click to play animation)

PyroCb in Australia

Suomi NPP VIIRS true-color image at 04:16 UTC on 04 December 2016 (click to enlarge)

Suomi NPP VIIRS true-color image at 04:16 UTC on 04 December 2016 (click to enlarge)

On 04 December 2016 a pyroCb developed to the west of Toowoomba in Queensland, Australia. A Suomi NPP VIIRS true-color image around 04:16 UTC (above) showed the early stage of the smoke plume in the Cecil Plains area, about 2 hours prior to the pyroCb formation.

Himawari-8 monitored the temporal evolution of the smoke plumes and pyroCb cloud, as well as the fire hot spots. Starting at 5:00 UTC on 04 December, the animation below (also available as an MP4) shows Himawari-8 0.63 µm visible (left) and 3.9 µm shortwave IR (right) . The pyroCb cloud (~27.5º S, 151.4ºE) formed around 6:00 UTC. In the shortwave IR images, the red pixels indicate very hot IR brightness temperatures exhibited by the fire source regions. Also note the characteristic warmer (darker gray) appearance of the pyroCb cloud on the shortwave IR images, compared to the larger meteorological cumulonimbus cloud that developed just to the south of the fire.

HIMAWARI-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

Himawari-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

In addition, the Himawari-8 10.4 μm IR channel allowed the cloud-top IR brightness temperature to be measured. The animation below, also starting at 5:00 UTC on 04 December, shows that the brightness temperature for the pyroCb cloud reached roughly -60ºC at 6:50 UTC (red color enhancement).

HIMAWARI-8 10.4 µm IR channel images (click to play animation)

Himawari-8 10.4 µm IR channel images (click to play animation)

CALIOP data from a CALIPSO satellite overpass on 05 December (below) captured the signature of the young pyroCb smoke plume aloft along the east coast of Australia. The feature is located above the cursor in each image, at an altitude of 12-13 km; note that the Depolarization Ratio values are very low (ruling out a typical cloud feature), and the Feature Mask flags it as Aerosol (orange).

CALIPSO CALIOP Total Attenuated Backscatter (click to enlarge)

CALIPSO CALIOP Total Attenuated Backscatter (click to enlarge)

CALIPSO CALIOP Depolarization Ratio (click to enlarge)

CALIPSO CALIOP Depolarization Ratio (click to enlarge)

CALIPSO CALIOP Feature Mask (click to enlarge)

CALIPSO CALIOP Feature Mask (click to enlarge)

For a surface perspective to compliment the satellite imagery, a few storm chasers took some great photos of the pyroCb. These pictures (courtesy of Nicholas McCarthy) show the large smoke columns that result in the formation of these pyroCb clouds. The first picture below shows the smoke from the wildfire rising up and forming these clouds with large vertical extent.

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PyroCb in Russia

On 19 September 2016 a pyroCb formed northwest of Lake Baikal in eastern Russia. Himawari-8 detected the smoke plumes and pyroCb cloud, as well as the fire hot spots. The pyroCb cloud (~57.4º N, 105.3ºE) formed around 8:20 UTC . Starting at 7:30 UTC on 19 September, the animation below (also available as an MP4) shows Himawari-8 0.63 µm visible (left) and 3.9 µm shortwave IR (right) . In the shortwave IR images, the red pixels indicate very hot IR brightness temperatures exhibited by the fire source regions.

HIMAWARI-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

HIMAWARI-8 0.63 µm visible channel (left) and 3.9 µm shortwave IR channel images (right) (click to play animation)

In addition, using Himawari-8 10.4 μm IR channel the cloud-top IR brightness temperature could be found. The animation below, starting at 8:00 UTC on 19 September, shows the brightness temperature for the pyroCb cloud reached -36.9ºC at 9:10 UTC (green color enhancement).

HIMAWARI-8 10.4 µm IR channel images (click to play animation)

HIMAWARI-8 10.4 µm IR channel images (click to play animation)

A slightly longer animation — covering the period from 06:00 to 09:20 UTC — of Himawari-8 Visible (0.64 μm), Shortwave Infrared (3.9 μm) and Infrared Window (10.4 μm) images is shown below. The pyroCb cloud formed near the center of the images, and the cold anvil of the cloud then moved rapidly northeastward.

Himawari-8 Visible (top), Shortwave Infrared (middle) and Infrared Window (bottom) images [click to play animation]

Himawari-8 Visible (top), Shortwave Infrared (middle) and Infrared Window (bottom) images [click to play animation]

The coldest IR brightness temperature on a 12:12 UTC Metop-B image (below, courtesy of Rene Servranckx) was -45.3 C.

Metop-B AVHRR Shortwave Infrared (left) and Longwave Infrared (right) images at 12:12 UTC [click to enlarge]

Metop-B AVHRR Shortwave Infrared (left) and Longwave Infrared (right) images at 12:12 UTC [click to enlarge]

Suomi NPP OMPS Aerosol Index images (courtesy of Colin Seftor) show the transport of smoke on 20 September . The maximum AI was found to be 11.9 at 59.23 N 108.9 E around 4:48 UTC. This is northeast of the original pyroCu and is consistent with the movement of the smoke and pyroCb cloud seen in the animations above.

OMPS Aerosol Index image on 20 September

OMPS Aerosol Index image on 20 September

A close-up view of the dense smoke pall on 19 September — which was entrained into the circulation of a compact middle-tropospheric (500 hPa) low pressure / enhanced vorticity lobe that was passing over the area of active fires — as seen on a Suomi NPP VIIRS true-color image (with VIIRS-detected fire hot spots in red) is shown below. There was also a compact 500 hPa cold pool of -20º C associated with this low/vorticity feature, which help to destabilize the atmosphere making the environment more conducive to pyroCb development.

Suomi NPP VIIRS true-color image + VIIRS-detected fire hot spots [click to enlarge]

Suomi NPP VIIRS true-color image + VIIRS-detected fire hot spots [click to enlarge]

A sequence of daily VIIRS true-color images during the 13-18 September period showed the increase in areal coverage of smoke across that region as fire activity ramped up (below).

Suomi NPP VIIRS true-color images during the 13-18 September period [click to enlarge]

Suomi NPP VIIRS true-color images during the 13-18 September period [click to enlarge]

Another Pioneer Fire pyroCb in Idaho

GOES-15 Visible (0.63 µm, top), Shortwave Infrared (3.9 µm, middle) and Infrared Window (10.7 µm, bottom) images [click to play animation]

GOES-15 Visible (0.63 µm, top), Shortwave Infrared (3.9 µm, middle) and Infrared Window (10.7 µm, bottom) images [click to play animation]

The Pioneer Fire in central Idaho produced another pyroCb cloud on 29 August 2016. GOES-15 (GOES-West) Visible (0.63 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.7 µm) images (above; also available as an MP4 animation) showed the development of the pyroCb, which exhibited a minimum cloud-top IR brightness temperature value of -56º C (darker orange color enhancement) at 0230 UTC on 30 August as it drifted east-northeastward over the Idaho/Montana border. This temperature corresponded to an altitude of 11.7 km (218 hPa) on the nearby Boise ID sounding (below).

Boise, Idaho rawinsonde report [click to enlarge]

Boise, Idaho rawinsonde report [click to enlarge]

1-km resolution POES AVHRR images (below; courtesy of René Servranckx) showed pyroCb cloud-top IR brightness temperatures as cold as -66.7º C at 0044 UTC and -60.4º C at 0122 UTC.

POES AVHRR Visible (upper left), Shortwave Infrared (upper right), Infrared Window (lower left) and false-color RGB (lower right) images [click to enlarge]

POES AVHRR Visible (upper left), Shortwave Infrared (upper right), Infrared Window (lower left) and false-color RGB (lower right) images [click to enlarge]

POES AVHRR Visible (upper left), Shortwave Infrared (upper right), Infrared Window (lower left) and false-color RGB (lower right) images [click o enlarge]

POES AVHRR Visible (upper left), Shortwave Infrared (upper right), Infrared Window (lower left) and false-color RGB (lower right) images [click o enlarge]

Another PyroCb in Idaho

On 24 August a pyroCb formed  from the Henry Creek Fire in Idaho. GOES-15 detected the smoke plumes and pyroCb cloud, as well as the fire hot spot. The pyroCb (43.4º N, 111.7º W) formed around 23:45 UTC .  Starting at 23:00 UTC on 24 August, the animation below (also available as an MP4) )shows GOES-15 (GOES-West) 0.63 µm visible (left) and 3.9 µm shortwave IR (right) . In the shortwave IR images, the red pixels indicate very hot IR brightness temperatures exhibited by the fire source regions.

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

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

Since GOES-15 has a lower resolution the brightness temperatures appeared warmer. A 1-km resolution NOAA-18 image at 00:02 UTC on 25 August (below; courtesy of René Servranckx) showed the cloud-top IR brightness temperature of the pyroCb to be -41.5º C (green color enhancement).

NOAA-18 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right).

NOAA-18 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right).

A second pyroCb in Idaho

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images, with surface reports plotted in yellow [click to play MP4

GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images, with surface reports plotted in yellow [click to play MP4 animation]

The Pioneer Fire in central Idaho produced another pyroCb cloud on 21 August 2016 (the first was on 19 August). GOES-14 was in SRSO-R mode, and sampled the fire with 1-minute imagery (above; also available as a large 73 Mbyte animated GIF) — a large smoke plume was evident on 0.63 µm Visible images as it moved eastward; large fire hot spots (red pixels) were seen on 3.9 µm Shortwave Infrared images; on 10.7 µm Infrared Window images, the cloud-top IR brightness temperature cooled to -35º C (darker green enhancement) between 2249-2307 UTC as it moved over Stanley Ranger Station (KSNY), not quite reaching the -40º C threshold to be classified as a pyroCb.

However, a 1-km resolution NOAA-19 AVHRR 10.8 µm Infrared Window image (below; courtesy of René Servranckx) revealed a minimum cloud-top IR brightness temperature of -48.3º C (dark green color enhancement).

NOAA-19 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right) [click to enlarge]

NOAA-19 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right) [click to enlarge]

A larger-scale comparison of the NOAA-19 AVHRR visible, shortwave infrared and infrared window images is shown below.

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]

NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]