PyroCb in Russia

Himawari-8

Himawari-8 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.4 µm, bottom) [click to play animation | MP4]

On 30 April, JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.4 µm) images (above) showed the formation of the first known pyroCb of the 2019 Northern Hemisphere wildfire season. The pyroCb developed within the warm sector of an approaching midlatitude cyclone (surface analyses) in the Russian Far East, between still-ice-covered Lake Bolon and the Amur River. The cloud-top infrared brightness temperature first reached the -40ºC “pyroCb threshold” at 0310 UTC; note that the pyroCb cloud top appears warmer (darker shades of gray) than those of surrounding thunderstorms in the Shortwave Infrared images — a characteristic of enhanced solar reflection off the smaller ice crystals that are found in pyroCb cirrus anvils.

A faster animation revealed the rapid northeastward run of the large pyroCb-producing fire on Shortwave Infrared imagery.

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

VIIRS True Color RGB and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP [click to enlarge]

In a sequence of three VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images from NOAA-20 and Suomi NPP as viewed using RealEarth (above), the coldest cloud-top infrared brightness temperature of the pyroCb was -59ºC — which closely corresponded to the tropopause temperature on 00 UTC rawinsonde data from Habarovsk (below), located just southwest of the fire region.

Plot of 00 UTC rawinsonde data from Habarovsk [click to enlarge]

Plot of 00 UTC rawinsonde data from Habarovsk [click to enlarge]


PyroCbs in Western Australia

Himawari-8

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Large bushfires burning in the southern portion of the state of Western Australia produced three pyroCb clouds on 01 March 2019. JMA Himawari-8 “Red” Visible (0.64 µm) images (above) showed that the pyroCb clouds drifted southeastward after formation.

Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) further revealed the 3 distinct pyroCb pulses — 2 originating from the southernmost fire located near 29.5ºS / 124.4ºE, and a smaller one originating from a fire located farther to the northwest. Cloud-top infrared brightness temperatures cooled to the -59 to -63ºC range for the pair of larger pyroCbs (which was close to the tropopause temperature of -64ºC on Perth soundings: plot | data) with temperatures reaching -51ºC with the smaller northernmost pyroCb. Also apparent was a surge of cooler air moving northeastward behind a surface trough, whose arrival appeared to coincide with the pyroCb formation. A time series of surface data from Forrest (YFRT) clearly showed the arrival of the cool, moist air behind the trough.

Himawari-8 "Clean" Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0537 UTC [click to enlarge]

Suomi NPP VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0537 UTC [click to enlarge]

As shown using RealEarth, an overpass of the Suomi NPP satellite provided a more detailed view of the first (and largest) pyroCb at 0537 UTC (above), with NOAA-20 capturing the second pyroCb cloud about an hour later at 0628 UTC (below). The coldest cloud-top infrared brightness temperature on the 0537 UTC Suomi NPP VIIRS image was -70ºC (darker black enhancement); in addition, there appeared to be an Above-Anvil Cirrus Plume associated with that pyroCb, extending southeastward from a subtle Enhanced-V signature at the upshear (northwestern) edge of the cloud (where the warmest temperature was -48ºC, green enhancement).

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0628 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0628 UTC [click to enlarge]

On Himawari-8 Shortwave Infrared (3.9 µm) images (below), the pyroCb clouds exhibited a warmer (darker gray) appearance compared to adjacent conventional cumulonimbus clouds — this is due to the fact that ice crystals ejected into the pyroCb anvils are smaller (due to their shorter residence time within the intense updrafts above the fires), and these smaller ice crystals are more effective reflectors of incoming solar radiation. The large flare-up of red-enhanced land during the day is due to highly reflective soils of the Great Victoria Desert that quickly become very hot.

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

PyroCb in South Africa

Meteosat-11 Visible (0.8 µm), Shortwave Infrared (3.92 µm) and Longwave Infrared Window (10.8 µm) images [click to play animation | MP4]

Meteosat-11 Visible (0.8 µm, top), Shortwave Infrared (3.92 µm, center) and Longwave Infrared Window (10.8 µm, bottom) images [click to play animation | MP4]

The Garden Route Fires had been burning since about 24 October 2018 near George along the southern coast of South Africa (media story). On 29 October, EUMETSAT Meteosat-11 High Resolution Visible (0.8 µm), Shortwave Infrared (3.92 µm) and Longwave Infrared Window (10.8 µm) images (above) showed an elongated west-to-east oriented thermal anomaly or fire “hot spot” (red pixels) just northeast of George (station identifier FAGG) on Shortwave Infrared imagery during the hours leading up to the formation of a pyrocumulonimbus (pyroCb) cloud around 1300 UTC. The pyroCb exhibited the characteristic warm (+10 to +15ºC, darker gray enhancement) shortwave infrared cloud-top signature just off the coast at 1315 UTC, — this is due to enhanced solar reflection off ice crystals that are smaller compared to those of conventional thunderstorm tops.

Zooming out a bit to follow the southeastward drift of the pyroCb cloud (below), the coldest cloud-top 10.8 µm infrared brightness temperature (BT) was -61ºC (darker red enhancement) at 1315 UTC — then the cloud tops remained in the -55 to -59ºC range (orange enhancement) for the next 6 hours or so. Leveraging the large difference between cold 10.8 µm and warm 3.92 µm BTs, NRL calculates a pyroCb index, which classified this feature as an “intense pyroCb” (1315 UTC | animation). The coldest 10.8 µm cloud-top BT of -61ºC roughly corresponds to an altitude of 13.5 km based on 12 UTC rawinsonde data from Port Elizabeth (plot | list).

Meteosat-11 Shortwave Infrared (3.92 µm, left) and Longwave Infrared Window (10.8 µm, right) images [click to play animation | MP4]

Meteosat-11 Shortwave Infrared (3.92 µm, left) and Longwave Infrared Window (10.8 µm, right) images [click to play animation | MP4]

Imagery from NOAA-19 at 1420 UTC (courtesy of René Servranckx) also revealed the warm (dark gray) Shortwave Infrared pyroCb signature, along with a minimum cloud-top infrared BT of -58.1ºC (below).

NOAA-19 imagery at 1640 UTC [click to enlarge]

NOAA-19 imagery at 1640 UTC [click to enlarge]

A Suomi NPP VIIRS True Color Red-Green-Blue (RGB) image att 1230 UTC (below) was about a half hour before the formation of the pyroCb, but it did show a signature of smoke drifting southeastward off the coast.

Suomi NPP VIIRS True Color RGB image [click to enlarge]

Suomi NPP VIIRS True Color RGB image [click to enlarge]

On the following day (30 October), a NOAA-20 VIIRS True Color image (below) showed the classic comma cloud signature of a mid-latitude cyclone south of the coast, with the band of cold-frontal clouds extending northward across Lesotho. Note the thick plume of smoke spreading eastward within the strong post-frontal westerly winds.

NOAA-20 VIIRS True Color RGB image [click to enlarge]

NOAA-20 VIIRS True Color RGB image [click to enlarge]

A time series of of surface observations from George (below) supported the idea of a cold frontal passage: ahead of the front, temperatures rapidly rose to 104ºF/40ºC (with a dew point of 39ºF/4ºC) on 28 October about 1.5 hours prior to the formation of the pyroCb — then strong westerly winds (gusting to 40 knots/21 mps) with rising pressures and falling temperatures followed on 30 October.

Time series plot of of surface observations from George [click to enlarge]

Time series plot of of surface observations from George [click to enlarge]

The pyroCb research community believes that this is the first documented case of a pyroCb on the African continent.

 

Delta Fire pyroCb in California

GOES-16

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Cloud Top Temperature product (bottom right) [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Cloud Top Temperature product images displayed using AWIPS (above) showed the formation of a pyroCumulonimbus (pyroCb) cloud generated by the Delta Fire in Northern California late in the day on 05 September 2018. As the pyroCb cloud drifted eastward toward the California/Nevada border, Cloud Top Temperature values cooled to a minimum of -53ºC (lighter green enhancement) at 0300 UTC. Note the pulsing behavior of updrafts over the fire area: 2 very distinct updraft pulses were apparent (at 0022 UTC and 0042 UTC), with the later pulse producing the pyroCb.


A longer animation of GOES-16 “Red” Visible, Shortwave Infrared and “Clean” Infrared Window images displayed using McIDAS (below) showed that the first hot (red) Shortwave Infrared pixels appeared at 2027 UTC. The fire caused a 5-mile section of Interstate 5 to be closed.

GOES-16 "Red" Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle), "Clean" Infrared Window (10.3 µm, bottom) images; Interstate 5 is plotted in cyan [click to play animation | MP4]

GOES-16 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.3 µm, bottom) images; Interstate 5 is plotted in cyan [click to play animation | MP4]

GOES-17 (positioned at 89.5º W longitude during its post-launch checkout phase) had a more direct view of the pyroCb than GOES-16 (positioned over the Atlantic Ocean at 75.2º W longitude) — and GOES-17 “Red” Visible, Shortwave Infrared and “Clean” Infrared Window images are shown below. Unfortunately the default GOES-17 Western US Mesoscale Domain Sector was shifted farther to the south on this day, so 1-minute imagery of the pyroCb event was not available.

GOES-17 "Red" Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle), "Clean" Infrared Window (10.3 µm, bottom) images; Interstate 5 is plotted in cyan [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.3 µm, bottom) images; Interstate 5 is plotted in cyan [click to play animation | MP4]

* GOES-17 images shown here are preliminary and non-operational *

Carr Fire pyroCb in California

GOES-16

GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the large thermal anomaly or “hot spot” (cluster of red pixels) associated with the Carr Fire in northern California as it produced a pyrocumulonimbus (pyroCb) cloud during the afternoon hours on 27 July 2018. A 30-meter resolution Landsat-8 False Color image from the previous day showed the large size of the burn scar; extreme fire behavior on 27 July caused the Carr Fire to quickly increase in size and move closer to Redding CA, and also produce the pyroCb.

Another view using GOES-16 “Red” Visible, Shortwave Infrared, “Clean” Infrared Window (10.3 µm) and the Cloud Top Temperature product (below) showed the pyroCb cloud as it drifted rapidly northeast over Nevada and Oregon, along with a second (albeit smaller) pyroCb cloud which developed around 0130 UTC. One standard parameter used for defining a pyroCb cloud is a minimum cloud-top longwave infrared brightness temperature of -40ºC (ensuring complete glaciation) — and in this case with 1-minute imagery, the multi-spectral Cloud Top Temperature (CTT) product (FAQ) indicated that the pyroCb cloud reached the -40ºC threshold 19 minutes earlier than the 10.3 µm infrared imagery. From that point forward, the CTT product was consistently at least 5-10ºC colder than the 10.3 µm brightness temperature; the CTT product eventually displayed a minimum value of -53.9ºC over northeastern California. Even as the 10.3 µm brightness temperature began to rapidly warm after about 0100 UTC, the CTT product continued to display values in the -45 to -50ºC range (shades of green) which allowed for unambiguous tracking of the pyroCb.

GOES-16 "Red" Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), "Clean" Infrared Window (10.3 µm, bottom left) and Cloud Top Temperature product (bottom right) [click to play MP4 animation]

GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Cloud Top Temperature product (bottom right) [click to play MP4 animation]

In the case of the second (smaller) pyroCb cloud that formed from the Carr Fire after 0130 UTC, the 10.3 µm brightness temperature failed to reach the -40ºC threshold, while the CTT product again displayed values in the -45 to -50ºC range. The coldest CTT value of -53.9ºC (seen with the initial pyroCb) roughly corresponded to an altitude of 12.5 km or 41,000 feet according to 00 UTC rawinsonde data from Reno, Nevada (below). Strong upper-tropospheric winds of 80-90 knots rapidly transported the pyroCb anvil northeastward.

Plot of 00 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Plot of 00 UTC rawinsonde data from Reno, Nevada [click to enlarge]

Cranston Fire pyroCb in California

GOES-16 GOES-16 “Red” Visible (0.64 µm, left) and Shortwave Infrared (3.9 µm, right) images, with hourly plots of surface reports [click to play animation | MP4]

GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke and pyrocumulus clouds as well as the thermal anomaly or “hot spot” (red pixels) associated with the Cranston Fire — located in the center of the images — which started southwest of Palm Springs, California (KPSP) around 1852 UTC or 11:52 am PDT on 25 July 2018. The large areas of red seen on the Shortwave Infrared images early in the animation were signatures of very hot sandy soil surfaces of the southern California deserts. Note the very warm airt temperatures seen across the region; Palm Springs had an afternoon high of 116ºF, and Thermal KTRM had a high of 119ºF.

A slightly different view — with the fire located in the lower left corner, southwest of KPSP — using GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (below) revealed that the fire actually produced 3 distinct pulses of pyroCumulonimbus (pyroCb) cloud, where the 10.3 µm cloud-top infrared brightness temperature reached or exceeded the -40ºC threshold (lime green enhancement). Three specific times that these separate pyroCb clouds were evident were 2102 UTC, 2147 UTC and 2312 UTC.

GOES-16 "Red" Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and "Clean" Infrared Window (10.3) images, with 4-letter airport identifiers plotted in yellow [click to play animation | MP4] GOES-16 “Red” Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and “Clean” Infrared Window (10.3 µm, right) images, with 4-letter airport identifiers plotted in yellow [click to play animation | MP4]

Another view of the pyroCb pulses was provided by a 4-panel view of GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Cloud Top Phase (below). The coldest 10.3 µm cloud-top infrared brightness temperatures were -55ºC as the primary pyroCb anvil drifted northeastward toward the California/Nevada border.

GOES-16 "Red" Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), "Clean" Infrared Window (10.3 µm, bottom left) and Cloud Top Phase (bottom right) images [click to play animation | MP4] GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Cloud Top Phase (bottom right) images [click to play animation | MP4]

There was also substantial lightning observed with these pyroCb clouds:

Below is a timelapse video of the first 8 hours of the fire, which shows the pyroCb evolution at the end.

Timelapse of Cranston Fire [click to play YouTube video] Timelapse of Cranston Fire [click to play YouTube video]

===== 26 July Update =====

GOES-16 "Red" Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), "Clean" Infrared Window (10.3 µm, bottom left) and Fire Temperature (bottom right) images [click to play animation | MP4] GOES-16 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), “Clean” Infrared Window (10.3 µm, bottom left) and Fire Temperature (bottom right) images [click to play animation | MP4]

Another pyroCb was produced by the Cranston Fire on 26 July, as shown by GOES-16 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.3 µm) and Fire Temperature images (above). Similar to the previous day, there appeared to be 2 pulses of pyroCb formation — with cloud-top infrared brightness temperatures cooling to -44ºC. Pyrocumulus from the smaller Ribbon Fire (just southeast of the Cranston Fire) could also be seen.