Prescribed burn in southern Wisconsin

October 19th, 2021 |

GOES-16 “Red” Visible (0.64 µm, top) and Shortwave Infrared (3.9 µm, bottom) images [click to play animated GIF | MP4]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke plume and thermal anomaly or “hot spot” (cluster of darker black pixels) associated with what was likely a prescribed burn at or near the Brooklyn Wildlife Area in south-central Wisconsin on 19 October 2021.

A toggle between the GOES-16 Shortwave Infrared image at 2027 UTC and a background Google Maps image — as viewed using RealEarth (below) — further implicated Brooklyn Wildlife Area as the likely fire source region.

GOES-16 Shortwave Infrared (3.9 µm) image at 2027 UTC, along with a Google Maps background [click to enlarge]

GOES-16 True Color RGB images created using Geo2Grid (below) offered a clearer depiction of the smoke plume, as it eventually moved northeastward over the Madison metro area.

GOES-16 True Color images [click to play animated GIF | MP4]

As the smoke plume moved over the Space Science and Engineering Center at the University of Wisconsin – Madison, the aerosol layer was detected by a rooftop High Spectral Resolution Lidar — generally within the 2-4 km altitude range (below).

UW-SSEC rooftop lidar images [click to enlarge]

A few miles to the northeast, the ceilometer at Madison Dane County Regional Airport also detected the base of the smoke plume aloft (below)

Plot of surface report data from Madison Dane County Regional Airport [click to enlarge]

Thanks to Kathy Strabala (SSEC) for bringing this case to our attention!

Alisal Fire in Southern California

October 12th, 2021 |

GOES-17 True Color RGB images [click to play animated GIF | MP4]

GOES-17 (GOES-West) True Color RGB images created using Geo2Grid (above) showed the transport of smoke from the Alisal Fire in Southern California on 12 October 2021. The dashed line in the images is Highway 101 — a portion of which was closed, as the wind-driven fire raced toward the coast. Late in the day some low-altitude smoke began to move eastward along the coast, eventually reducing the surface visibility to 6 miles at Santa Barbara.

During the preceding overnight hours (at 0916 UTC or 2:16 am PDT), a comparison of Suomi-NPP VIIRS Shortwave Infrared and Day/Night Band images (below) revealed the thermal signature and nighttime glow of the fire. The VIIRS imagery was downloaded and processed via the SSEC/CIMSS Direct Broadcast ground station.

Suomi-NPP VIIRS Shortwave Infrared (3.74 µm) and Day/Night Band (0.7 µm) images [click to enlarge]

The Suomi-NPP overpass time of the fire region was actually 0926 UTC — and a time-matched comparison of Shortwave Infrared images from GOES-17 and Suomi-NPP (below) demonstrated that the superior spatial resolution of VIIRS instrument (~375 meters, vs ~2 km for the ABI on GOES-17) provided a more accurate depiction of the areal coverage of the fire.

Shortwave Infrared images from Suomi-NPP (3.74 µm) and GOES-17 (3.9 µm) [click to enlarge]

===== 13 October Update =====

GOES-17 True Color RGB images [click to play animated GIF | MP4]

On 13 October, GOES-17 True Color RGB images (above) showed that as offshore wind speeds relaxed, a shift to onshore flow recirculated some of the smoke inland — with smoke briefly reducing the surface visibility to 1.5 miles at Santa Barbara airport (below). Farther to the south, residual smoke from the previous day of burning was also evident, with some of it traveling as far as Isla Guadalupe (Guadalupe Island) nearly 400 miles away.

Time series of surface observation data from Santa Barbara Municipal Airport [click to enlarge]

Pyrocumulonimbus clouds spawned by the KNP Complex wildfire in California

October 4th, 2021 |

GOES-17 Visible (0.64 µm, center), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.35 µm, bottom) images [click to play animation | MP4]

The KNP Complex wildfire continued to burn in central California on 04 October 2021, producing a pair of pyrocumulonimbus or pyroCb clouds — one during the atypical late morning hours (beginning around 1530 UTC, or 11:30 am PDT) and the other during the more typical late afternoon hours (beginning around 2130 UTC, or 5:30 PM PDT). 1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the pyroCB clouds, fire thermal anomalies or “hot spots” (clusters of red pixels) and cold cloud-top infrared brightness temperatures, respectively. The minimum 10.35 µm temperatures were near -60ºC. Note the relatively warm (darker gray) appearance of the pyroCb clouds in the 3.9 µm images — this is a characteristic signature of pyroCb cloud tops, driven by the smoke-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation, contributing to the warmer 3.9 µm brightness temperatures). Note: beginning at 1700 UTC, overlapping GOES-17 Mesoscale Sectors provided imagery at 30-second intervals.

1-minute GOES-17 True Color RGB images created using Geo2Grid (below) showed the first pyroCb cloud as it continued to move northeastward across the California/Nevada border, and then the second pyroCb cloud as it moved northwestward. The change in direction of motion was influenced by the approach of an offshore closed low from the west (250 hPa analysis: 12 UTC | 00 UTC). 

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

Pyrocumulonimbus cloud over northern Paraguay

September 29th, 2021 |

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.35 µm, bottom) images [click to play animation | MP4]

Fires burning in far northern Paraguay on 29 September 2021 created a pyrocumulonimbus or pyroCb cloud — GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.35 µm) images (above) showed the pyroCB cloud, fire thermal anomalies or “hot spots” (clusters of red pixels) and cold cloud-top infrared brightness temperatures, respectively. The minimum 10.35 µm temperature was -47.6ºC at 1840 UTC. Note the relatively warm (darker gray) appearance of the pyroCb cloud in the 3.9 µm images — this is a characteristic signature of pyroCb cloud tops, driven by the smoke-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation).

A Suomi-NPP VIIRS Infrared Window (11.45 µm) image at 1751 UTC as viewed using RealEarth (below) revealed cloud-top infrared brightness temperatures in the -60s C (shades of red). Surface temperatures at nearby sites had reached 38ºC (100ºF) by 18 UTC. 

Suomi-NPP VIIRS Infrared Window (11.45 µm) image at 1751 UTC [click to enlarge]

South American pyrocumulonimbus clouds are fairly uncommon — since the first documented case in 2018, only 7 other pyroCbs have been identified over that continent. 

Thanks to Mike Fromm, NRL, for alerting us to this latest pyroCb case. Additional information is available from Metsul.com.