2 structural fires: Beaver Dam, Wisconsin and San Francisco, California

March 17th, 2018 |

GOES-16 Shortwave Infrared (3.9 µm, left) and

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

As documented by NWS Milwaukee/Sullivan, the controlled burn of an apartment building occurred during the late morning hours on 15 March 2018. A comparison of GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) and “Red” Visible (0.64 µm) images (above) displayed subtle “hot spot” signatures (darker red pixels, circled) as well as an occasional hint of a small smoke plume during the early phase of the fire. At the bottom of the images, note the appearance of a few larger and hotter fires (black pixels) in northern Illinois — likely agricultural fires to prepare fields for Spring planting.

2 days later, another structure fire occurred in the San Francisco area during the early evening hours of 17 March 2018:

Hot spot signatures were observed on the 0247 UTC and 0252 UTC (7:47 and 7:52 PM local time) Shortwave Infrared (3.9 µm) images, along with subtle lighter gray pixels on the Near-Infrared (2.24 µm) images (below).

GOES-16 Shortwave Infrared (3.9 µm, left) and Near-Infrared (2.24 µm, right) images, with station identifiers plotted in cyan [click to play animation]

GOES-16 Shortwave Infrared (3.9 µm, left) and Near-Infrared (2.24 µm, right) images, with airport identifiers plotted in cyan [click to play animation]

A timely overpass of the NOAA-15 satellite scanned the fire at 02:43:50 UTC (7:43:50 PM local time), showing a well-defined hot spot (darker red enhancement) on the 1-km resolution Shortwave Infrared (3.7 µm) image (below).

NOAA-15 Shortwave Infrared (3.7 µm) image [click to enlarge]

NOAA-15 Shortwave Infrared (3.7 µm) image [click to enlarge]

Pyrocumulonimbus cloud in Argentina

January 29th, 2018 |

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.3 µm) images [click to play animation]

GOES-16 Visible (0.64 µm, top), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.3 µm, bottom) images [click to play animation]

A large cluster of fires burning in central Argentina became hot enough to generate a brief pyrocumulonimbus (pyroCb) cloud on 29 January 2018; according to media reports, on that day there were winds of 55 km/hour (34 mph) and temperatures of 37 ºC (98.6 ºF) in the vicinity of these La Pampa province fires. GOES-16 (GOES-East) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and “Clean” Infrared Window (10.3 µm) images (above; also available as an MP4 animation) showed the smoke plumes, fire thermal anomalies or “hot spots” (red pixels) and the cold cloud-top infrared brightness temperatures, respectively. The minimum 10.3 µm temperature was -32.6 ºC at 1745 UTC. Note the relatively warm (darker gray) appearance on the 3.9 µm image — this is a characteristic signature of pyroCb clouds tops, driven by the aerosol-induced shift toward smaller ice particles (which act as more efficient reflectors of incoming solar radiation).

An Aqua MODIS True-color Red-Green-Blue (RGB) image viewed using RealEarth (below) showed the dense lower-tropospheric smoke drifting southward and southeastward from the fire source region, as well as the narrow upper-tropospheric anvil of the pyroCb cloud. Suomi NPP VIIRS fire detection locations are plotted as red dots on the final zoomed-in image. The actual time of the Aqua satellite pass over Argentina was 1812 UTC.

Aqua MODIS True-color RGB image, with Suomi NPP VIIRS fire detection locations [click to enlarge]

Aqua MODIS True-color RGB image, with Suomi NPP VIIRS fire detection locations [click to enlarge]

According to Worldview the coldest MODIS Infrared Window (11.0 µm) cloud-top  brightness temperature was -41.2 ºC, thus surpassing the -40 ºC threshold that is generally accepted to classify it as a pyroCb. This is believed to be the first confirmed pyroCb event in South America.

Approximately 120 km north-northeast of the pyroCb cloud, rawinsonde data from Santa Rosa, Argentina (below) indicated that the -41 ºC cloud-top temperature corresponded to altitudes in the 10.8 to 11.6 km range. The air was very dry at that level in the upper troposphere, contributing to the rapid dissipation of the pyroCb cloud material as seen in GOES-16 imagery.

Plots of rawinsonde data from Santa Rosa, Argentina [click to enlarge]

Plots of rawinsonde data from Santa Rosa, Argentina [click to enlarge]

48-hour HYSPLIT forward trajectories originating from the center of the pyroCb cloud at altitudes of 7, 9 and 11 km (below) suggested that a rapid transport of smoke over the adjacent offshore waters of the Atlantic Ocean was likely at those levels.

HYSPLIT forward trajectories originating at altitudes of 7, 9 and 11 km [click to enlarge]

HYSPLIT forward trajectories originating at altitudes of 7, 9 and 11 km [click to enlarge]

On 30 January, Suomi NPP OMPS Aerosol Index values (below; courtesy of Colin Seftor, SSAI at NASA Goddard) were as high as 4.3 over the South Atlantic (at 41.81º South latitude, 53.22º West longitude, 17:31:34 UTC) — consistent with the HYSPLIT transport originating at 7 km.

Suomi NPP OMPS Aerosol Index on 30 January [click to enlarge]

Suomi NPP OMPS Aerosol Index on 30 January [click to enlarge]

Additional Suomi NPP VIIRS True-color and OMPS Aerosol Index images can be found on the OMPS Blog.

===== 01 February Update =====

This analysis of CALIPSO CALIOP data (courtesy of Mike Fromm, NRL) suggests that the upper-tropospheric smoke from this pyroCb event was transported as far as the eastern South Atlantic Ocean by 02 UTC on 01 February, having ascended to altitudes in the 9-10 km range.

A prescribed burn in Montana, as viewed from GOES-15, GOES-16 and GOES-13

January 2nd, 2018 |

GOES-15 (left), GOES-16 (center) and GOES-13 (right) Shortwave Infrared (3.9 µm) images, with plots of hourly surface reports [click to play MP4 animation]

GOES-15 (left), GOES-16 (center) and GOES-13 (right) Shortwave Infrared (3.9 µm) images, with plots of hourly surface reports [click to play MP4 animation]

A prescribed burn the SureEnough fire — in central Montana was viewed by GOES-15 (GOES-West), GOES-16 (GOES-East) and GOES-13 Shortwave Infrared (3.9 µm) imagery on 02 January 2018. The images are shown in the native projection for each of the 3 satellites.

Due to the improved spatial resolution of the GOES-16 3.9 µm Shortwave Infrared band (2 km at satellite sub-point, vs 4 km for GOES-15 and GOES-13) and the more frequent image scans (routinely every 5 minutes over CONUS for GOES-16), an unambiguous thermal anomaly or fire “hot spot” was first evident on GOES-16 at 1707 UTC, just southeast of Lewistown (station identifier KLWT). The GOES-16 fire thermal signature was also hotter (black pixels) compared to either GOES-15 or GOES-13.

Day 14 of the Thomas Fire in Southern California

December 17th, 2017 |

GOES-15 Shortwave Infrared (3.9 µm) images, with surface station identifiers plotted in yellow [click to play MP4 animation]

05-17 December GOES-15 Shortwave Infrared (3.9 µm) images, with surface station identifiers plotted in yellow and State Highway 101 plotted in cyan [click to play MP4 animation]

The Thomas Fire (InciWeb | Wikipedia) began to burn around 0226 UTC on 05 December 2017 (or 6:26 PM Pacific time on 04 December). By 17 December, the fire had burned 270,000 acres — the third largest wildfire on record in California — and caused 1 fatality. An animation of GOES-15 (GOES-West) Shortwave Infrared (3.9 µm) images (above) showed the evolution of the thermal signature (or “hot spots”, as depicted by darker black to yellow to red pixels) during the 0200 UTC 05 December to 0215 UTC 18 December time period. Besides the largest Thomas Fire, other smaller and more short-lived fires could also be seen — especially early in the period, when the Santa Ana winds were strongest (05-07 December blog post). Thick clouds moving over the region later in the period either attenuated or completely masked the thermal signatures, even though the fire was ongoing.

GOES-16 began transmitting imagery (from its GOES-East position at 75.2º W) at 1630 UTC on 14 December — a comparison of GOES-15 and GOES-16 Shortwave Infrared (3.9 µm) during the 14-17 December period (below) showed that in spite of the larger GOES-16 satellite view angle (62.6º, vs 43.2º for GOES-15), the improved spatial resolution (2 km vs 4 km at satellite sub-point) and improved temporal resolution (images every 5 minutes, with no 30-minute gaps due to Full Disk scans) provided a more accurate depiction of the fire trends and intensities.

GOES-15 (left) and GOES-16 (right) Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-15 (left) and GOES-16 (right) Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

In a comparison of 250-meter resolution Terra MODIS true-color and false-color Red-Green-Blue (RGB) images (source) at 1853 UTC on 17 December (below), minimal amounts of smoke and a lack of clouds allowed a good view of the large Thomas Fire burn scar (darker shades of reddish-brown) on the false-color image.

Terra MODIS true-color and false-color RGB images on 17 December [click to enlarge]

Terra MODIS true-color and false-color RGB images on 17 December [click to enlarge]

During the first full day of the fires on 05 December, a toggle between comparable Aqua MODIS true-color and false-color images (source) revealed very thick smoke plumes drifting southwestward over the adjacent offshore waters of the Pacific Ocean (below).

Aqua MODIS true-color and false-color images, 05 December [click to enlarge]

Aqua MODIS true-color and false-color RGB images on 05 December [click to enlarge]

A toggle between 05 December Aqua MODIS and 17 December Terra MODIS false-color images (below) showed the northward and northwestward growth of the Thomas Fire burn scar.

Aqua MODIS (05 December) and Terra MODIS (17 December) false-color RGB images [click to enlarge]

Aqua MODIS (05 December) and Terra MODIS (17 December) false-color RGB images [click to enlarge]