Wildfires in British Columbia

August 17th, 2018 |

GOES-16

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

A 2-panel comparison of GOES-16 (GOES-East) “Red” Visible (0.64 µm) and Shortwave Infrared (3.9 µm) images (above) showed the smoke plumes and thermal anomalies or “hot spots” (darker black to red pixels) associated with a flare-up of wildfires in western British Columbia on 17 August 2018.

A sequence of Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS (below) revealed the diurnal changes in areal coverage and intensity of the thermal signature of the fires.

Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS [click to enlarge]

Shortwave Infrared (3.7 µm) images from Terra / Aqua MODIS and Suomi NPP / NOAA-20 VIIRS [click to enlarge]

Toggles between Visible and Shortwave Infrared images from Terra MODIS (1912 UTC), NOAA-20 VIIRS (1950 UTC) ans Suomi NPP VIIRS (2129 UTC) are shown below (note: the NOAA-20 images are incorrectly labeled as Suomi NPP). It is interesting to note the impact that the smoke plume had on the air temperature at Quesnel (CYQZ) — because the smoke layer was optically dense enough (VIIRS True Color image) to significantly reduce incoming solar radiation, the temperature was as much as 14-18ºF (8-10ºC) cooler than Prince George (CYXS) to the north and Williams Lake (CYWL) to the south.

Terra MODIS Visible (0.65 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

Terra MODIS Visible (0.65 µm) and Shortwave Infrared (3.7 µm) images at 1912 UTC [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images [click to enlarge]

NOAA-20 VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 1950 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 2129 UTC [click to enlarge]

Suomi NPP VIIRS Visible (0.64 µm) and Shortwave Infrared (3.74 µm) images at 2129 UTC [click to enlarge]

===== 19 August Update =====

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

GOES-17 Near-Infrared

GOES-17 Near-Infrared “Cloud Particle Size” (2.24 µm, left) and Shortwave Infrared (3.9 µm, right) images [click to play 81 Mbyte MP4 animation]

A 2-panel comparison of GOES-17 Near-Infrared “Cloud Particle Size” (2.24 µm) and Shortwave Infrared (3.9 µm) images during the 7-day period of 13-19 August (above) showed the diurnal changes in thermal signatures of the ongoing British Columbia wildfires. The nighttime thermal signatures seen on the 2.24 µm images (brighter white pixels) result from the fact that this spectral band is located close to the peak emitted radiance of very hot features such as active volcanoes or large fires (below).

Plots of Spectral Response Functions for ABI Bands 5, 6 and 7 [click to enlarge]

Plots of Spectral Response Functions for ABI Bands 5, 6 and 7 [click to enlarge]

Stereoscopic view of Severe Convection over Nebraska

August 16th, 2018 |

GOES-16 (Left) and GOES-17 (Right) Visible (0.64 µm) Imagery over Nebraska, 1902 UTC 15 August – 0157 UTC 16 August 2018 (Click to play mp4 animation)

GOES-17 Data shown in this post are preliminary and non-operational!

A Strong thunderstorm developed over Nebraska on 15 August (read more below), depositing baseball-sized hail in Arthur County. This storm was sampled by a GOES-16 Mesoscale sector, and the 1-minute imagery allowed views of the rotating updraft (Link). The stereoscopic view above, from the GOES-16 and GOES-17 CONUS sectors, shows the development and evolution of the storm at 5-minute increments (Click here for animated gif). To view the storm in three dimensions, cross your eyes until you view 3 images, and focus on the image in the middle. This storm develops the above-anvil cirrus plume that has been shown to be associated with severe weather, as in this case.

Severe thunderstorms in South Dakota and Nebraska

August 15th, 2018 |

GOES-16

GOES-16 “Red” Visible (0.64 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

1-minute Mesoscale Domain Sector GOES-16 (GOES-East) “Red” Visible (0.64 µm) images (above) showed the development of thunderstorms which produced large hail and damaging winds across parts of southwestern South Dakota and western/central Nebraska (SPC storm reports) on 15 August 2018. The dominant storm in Nebraska exhibited a well-defined Above Anvil Cirrus Plume (AACP), which is often an indicator of a storm producing severe weather such as tornadoes, hail and wind (reference). Also note the slow-moving parallel bands of boundary layer wave clouds or “billow clouds” in northwestern Nebraska — this is a signature of warmer air flowing along the top of a low-level temperature inversion (caused by a pool of cold outflow from earlier thunderstorms). A stereoscopic view of this convection (using GOES-16 and GOES-17 visible images) can be seen here.

The corresponding GOES-16 Mid-level Water Vapor (6.9 µm) images (below) better revealed the broad circulation of the middle-tropospheric low that was centered over South Dakota (500 hPa analysis).

GOES-16 Mid-level Water Vapor (6.9 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 Mid-level Water Vapor (6.9 µm) images, with SPC storm reports plotted in red [click to play MP4 animation]

GOES-16 "Clean" Infrared Window (10.4 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images, with SPC storm reports plotted in purple [click to play MP4 animation]

GOES-16 “Clean” Infrared Window (10.3 µm) images (above) showed that the coldest cloud-top infrared brightness temperatures associated with thunderstorm overshooting tops were around -60ºC (darker red enhancement) — slightly warmer than that of the tropopause on rawinsonde data from North Platte, Nebraska (below).

Plots of rawinsonde data from North Platte, Nebraska at 12 UTC on 15 August and 16 August [click to enlarge]

Plots of rawinsonde data from North Platte, Nebraska at 12 UTC on 15 August and 16 August [click to enlarge]

Regarding the AACP feature, in this case the plume was colder than the adjacent underlying thunderstorm anvil, as seen in a toggle between GOES-16 Visible and Infrared images at 0005 UTC when the storm produced a wind gust of 70 mph at the surface (below). The temperature profile and lapse rate of the upper tropospheric/lower stratospheric air directly above the thunderstorm top will have in influence on whether an AACP is warmer or colder than the underlying thunderstorm anvil surface.

GOES-16

GOES-16 “Red” Visible (0.64 µm) and “Clean” Infrared Window (10.3 µm) images at 0005 UTC [click to enlarge]

Finally, when trying to correlate the location of storm-top satellite image features with reports of hail/wind/tornadoes at the surface, it is important to factor in the effect of parallax. The GOES-16 satellite (positioned over the Equator at 75.2º W longitude) viewing angle for the North Platte area is 54 degrees — which has the effect of shifting the apparent location of storm-top features to the northwest of their true location over the Earth’s surface. The pair of image toggles shown below demonstrate how the “parallax-corrected” (northwest-shifted) location of the hail or wind reports more closely aligns with the cold overshooting top (orange to red enhancement) associated with the strongest storm updraft at that time.

GOES-16

GOES-16 “Clean” Infrared Window (10.3 µm) image at 2234 UTC, with the actual and “parallax-corrected” locations of a 2.75-inch hail report [click to enlarge]

GOES-16 "Clean" Infrared Window (10.3 µm) image at 0005 UTC, with the actual and parallax-corrected locations of a 70 mph wind gust [click to enlarge]

GOES-16 “Clean” Infrared Window (10.3 µm) image at 0005 UTC, with the actual and “parallax-corrected” locations of a 70 mph wind gust report [click to enlarge]

Carr Fire in northern California

August 11th, 2018 |
GOES-15, GOES-14, GOES-17 and GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

GOES-15, GOES-14, GOES-17 and GOES-16 Shortwave Infrared (3.9 µm) images [click to play MP4 animation]

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

A comparison of GOES-15 (GOES-West), GOES-14, GOES-17 and GOES-16 (GOES-East) Shortwave Infrared (3.9 µm) images (above) showed the thermal anomaly or “hot spot” (dark black to red pixels) associated with the Carr Fire in northern California on 11 August 2018. A GOES-16 Mesoscale Domain Sector was providing images at 1-minute intervals. This comparison demonstrates how fire detection can be affected by both satellite viewing angle and shortwave infrared detector spatial resolution (4 km at satellite sub-point for the GOES-14/15 Imager, vs 2 km for the GOES-16/17 ABI).

A toggle between 30-meter resolution Landsat-8 False Color and Thermal Infrared (10.9 µm) imagery viewed using RealEarth (below) showed new fire activity (clusters of red pixels) along the northeastern edge of the Carr Fire burn scar on the False Color image, as well as smoke plumes drifting northeastward; the heat signatures (brighter white pixels) of smaller fires hidden by the smoke were more clearly ssen on the Thermal Infrared image. As of this date the Carr Fire was the 8th largest and 6th most destructive fire on record in California, and was responsible for 8 fatalities.

Landsat-8 False Color and Thermal Infrared (10.9 µm) images [click to enlarge]

Landsat-8 False Color and Thermal Infrared (10.9 µm) images [click to enlarge]