Pyrocumulonimbus clouds in Oregon, Idaho and California

September 10th, 2022 |

An extended period of hot temperatures across much of the western US — where drought conditions were widespread — helped set the stage for large wildfires which produced several pyrocumulonimbus (pyroCb) clouds in parts of Oregon, Idaho and California during the 07-10 September 2022 period.

===== 07 September =====

GOES-18 Day Land Cloud Fire RGB images [click to play animated GIF | MP4]

GOES-18 (GOES-West) Day Land Cloud Fire RGB images (above) displayed numerous wildfires (clusters of red pixels) from far eastern Oregon into Idaho on 07 September 2022. Three of the larger fires — one in Oregon and two in Idaho — produced one or more pulses of pyroCb clouds during the day.

1-minute GOES-18 True Color RGB images visualized using CSPP GeoSphere (below) showed the smoke-laden cloud tops (shades of tan) associated with some of the pyroCb pulses from the eastern Oregon and central Idaho wildfires.

GOES-18 True Color RGB images [click to play MP4 animation]

4-panel displays of 1-minute Mesoscale Domain Sector GOES-18 Day Land Cloud Fire RGB, Shortwave Infrared (3.9µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature (below) provided a closer view of a vigorous pyroCb produced by the Moose Fire in far eastern Idaho (near the Montana border). During that time period, the maximum surface 3.9 µm infrared brightness temperature of the fire signature reached 137.88oC (the saturation temperature of GOES-18 ABI Band 7 detectors). The coldest pyroCb cloud-top 10.35 µm infrared brightness temperatures were -52oC, while the coldest Cloud Top Temperature derived product values were around -56oC.

GOES-18 Day Land Cloud Fire RGB (top left), Shortwave Infrared (3.9 µm, top right), Infrared Window (10.35 µm, bottom left) and Cloud Top Temperature (bottom right) [click to play animated GIF | MP4]

===== 08 September =====

GOES-17 “Red” Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, middle) and “Clean” Infrared Window (10.35 µm, bottom) [click to play animated GIF | MP4]

1-minute GOES-17 (which resumed duty as GOES-West as of 1601 UTC on 08 September) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed a “marginal” pyroCb produced by the Mosquito Fire in California on 08 September 2022, whose coldest cloud-top 10.35 µm infrared brightness temperature reached -39oC (just shy of the -40oC threshold of pyroCb classification) — however, the Cloud Top Temperature derived product (not shown) did reach -42oC.

1-minute GOES-17 True Color RGB images (below) displayed the smoke-laden (shades of tan) cloud top of this “marginal pyroCb”.

GOES-17 True Color RGB images [click to play MP4 animation]

===== 10 September =====

As discussed in this blog post, the Cedar Creek Fire in Oregon had been producing a large smoke plume during the day on 09 September — and this trend continued into the overnight hours, as shown by a Suomi-NPP VIIRS Day/Night Band (0.7 µm) image valid at 1020 UTC on 10 September (below). Ample illumination by a Full Moon provided an excellent example of the “visible image at night” capability of the Day/Night Band (DNB).

Suomi-NPP VIIRS Day/Night Band (0.7 µm) image, valid at 1020 UTC on 10 September [click to enlarge]

In a closer view of of the Cedar Creek Fire, a toggle between the corresponding Suomi-NPP VIIRS DNB and Shortwave Infrared images (below) displayed the bright nighttime glow of the more active individual fires (as well as the dense smoke plume drifting northwestward) in the DNB image — and the thermal signature of fires along the northwestern perimeter was evident in the Shortwave Infrared image, even though the dense smoke plume was overhead.

Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images, valid at 1020 UTC on 10 September [click to enlarge]

During the subsequent daytime hours, a sequence of 1-minute GOES-17 Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature product (below) showed that the Cedar Creek Fire produced a pyroCb cloud late in the day on 10 September 2022. During that particular time period, the maximum surface 3.9 µm infrared brightness temperature of the fire signature reached 138.71oC (the saturation temperature of GOES-17 ABI Band 7 detectors). The coldest cloud-top 10.35 µm infrared brightness temperature was -45oC, while the coldest Cloud Top Temperature derived product value was -49oC.

Sequence of GOES-17 Day Land Cloud Fire RGB, Shortwave Infrared (3.9 µm), “Clean” Infrared Window (10.35 µm) and Cloud Top Temperature product [click to play animated GIF | MP4]

1-minute GOES-17 True Color RGB images (below) showed the Cedar Creek Fire pyroCb rising through and towering above the large pall of lower-altitude smoke.

GOES-17 True Color RGB images [click to play MP4 animation]

During the following overnight hours, a toggle between Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images valid at 1002 UTC (below) revealed that the nighttime glow and thermal signature of larger active fires along the perimeter of the Cedar Creek Fire were still apparent, in spite of dense smoke that lingered over the area and high clouds that were beginning to move overhead from the west.

Suomi-NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (11.45 µm) images, valid at 1002 UTC on 11 September [click to enlarge]

Wildfires in Idaho

September 4th, 2022 |

GOES-18 Fire Temperature RGB images, with GOES-17 Fire Detection and Characterization Algorithm products [click to play animated GIF | MP4]

Overlapping 1-minute Mesoscale Domain Sectors provided 30-second GOES-18 (GOES-West) Fire Temperature RGB images, along with GOES-17 Fire Detection and Characterization Algorithm (FDCA) products (above) — which showed thermal signatures of the larger Ross Fork Fire and the smaller Wildhorse Fire in southern Idaho on 04 September 2022. The Wildhorse Fire caused a closure of US Highway 20, just west of Hill City, for a period of 12 hours.

The Ross Fork Fire burned very hot, with Shortwave Infrared (3.9 µm) infrared brightness temperatures reaching 137.88ºC (the saturation temperature of GOES-18 ABI Band 7 detectors). For those hottest fire pixels, occasionally FDCA parameters (Fire Temperature, Fire Power, Fire Area and Fire Mask) were generated and displayable via AWIPS cursor sampling (below).

GOES-18 Fire Temperature RGB image, with GOES-17 FDCA cursor values for a Processed Fire [click to enlarge]

Note, however, that FDCA parameters were not displayable in AWIPS for Cloudy Fires (fires with partial obscuration by pyrocumulus clouds and/or optically-thick smoke) or for Saturated Fires (below). Part of this issue is related to the fact that the peak GOES-18 3.9 µm temperature (137.88ºC) was slightly lower than the peak 3.9 µm value for GOES-16/-17 (138.71ºC).

GOES-18 Fire Temperature RGB image, with GOES-17 FDCA cursor values for a Saturated Fire [click to enlarge]

 

GOES-18 Fire Temperature RGB image, with GOES-17 FDCA cursor values for a Cloudy Fire [click to enlarge]

Cedar Creek Fire in Oregon

September 2nd, 2022 |

GOES-18 Day Land Cloud Fire RGB (top left), GOES-18 Shortwave Infrared (3.9 µm, top right), GOES-17 Fire Power (bottom left) and GOES-17 Fire Temperature (bottom right) [click to play animated GIF | MP4]

GOES-18 (GOES-West) Day Land Cloud Fire RGB and Shortwave Infrared (3.9 µm) images along with GOES-17 Fire Power and Fire Temperature products (above) displayed characteristics associated with the Cedar Creek Fire in Oregon on 02 September 2022. The peak 3.9 µm infrared brightness temperature reached 137.88ºC, with Fire Power values exceeding 2000 MW and Fire Temperature values exceeding 1200 K. The Fire Power and Fire Temperature products are components of the Fire Detection and Characterization Algorithm (FDCA).

GOES-18 True Color RGB images created using CSPP GeoSphere (below) showed the large smoke plume produced by this wildfire, which spread north-northeastward across Washington State during the day.

GOES-18 True Color RGB images [click to play MP4 animation]

Satellite imagery and multiple earthquakes near American Samoa

August 25th, 2022 |
False Color imagery over the American Samoa sector, 1610 UTC on 25 August 2022 (Click to enlarge)

Seismic activity has been ongoing in August 2022 beneath the island of Ta’u to the east of American Samoa. (USGS has published a variety of information on this swarm of Earthquakes: link 1; link 2; link 3); See also these two recorded Facebook Live presentations from the NWS WSO office in Pago Pago: (August 22nd and August 17th). Volcano updates fro Ta’u can also be viewed here.

The Volcanic Ash Advisory Center (VAAC) that has responsibility for this region of the south Pacific is Wellington NZ. Click here for a pdf that shows all VAAC boundaries.

Should an eruption occur (NOTE: An eruption is not expected in the near term!), what kind of satellite information will be useful? The Volcanic Cloud Monitoring website (link) from CIMSS includes imagery over various sectors on Earth, sorted by VAAC. For American Samoa, and adjacent regions, Choose ‘Satellite Imagery’ and under the ‘Sector’ menu, and then choose, under the Wellington VAAC subsection, ‘American Samoa (750 m)’ Both GOES-17 / GOES-18 and Himawari view the region, but GOES-17/GOES-18 sub-satellite points are closer to American Samoa and will provide better resolution views. (NOAA-20 and Suomi-NPP as polar orbiters will provide the highest spatial resolution data, but have poor temporal resolution). You can choose various image types at the website: quantitative estimates of Ash Loading, Ash Height, Ash Loading, Ash Reflectivity, Single-channel Brightness Temperatures (or Reflectivity), and various Red/Green/Blue composites. Note that this website has an extensive explanatory section (under the ‘Tutorials’ tab) to help you understand what you’re seeing in the imagery. The GOES-18 false-color image red/green/blue image, above, is the from the website. An eruption is not occurring, nor detected, in the image.

Various websites also allow views of Satellite Imagery over the region. For example, the CSPP Geosphere site includes True-Color imagery (day) and Night time Microphysics (night) by default, but also allows a user to view single channels. (Direct link, see an example below) There is also a NOAA/NESDIS site that includes some RGBs and each of the individual bands; the CIRA Slider also includes imagery over the south Pacific.

Night Microphysics RGB near American Samoa, 1700 UTC on 25 August 2022 (Click to enlarge)

Wind direction will be important if an eruption occurs (this is at present unlikely!!) to know as that will control the dispersion of any gases. The windy.com website will provide this with this link.


This blog entry is meant to be a resource should an eruption occur. (Note: that is not expected!) For more information, please refer to the USGS website, and the American Samoa Facebook page.