The King Fire in California

September 19th, 2014
Suomi NPP VIIRS true-color images

Suomi NPP VIIRS true-color images

The King Fire began burning in central California (between Sacramento and Lake Tahoe) during the evening hours on 13 September 2014. A sequence of daily (12-19 September) Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server site (above) showed that as the prevailing southwesterly wind pattern switched to easterly on 19 September, there was a major change in the transport of smoke from the King Fire. The final image in the series zooms out to show how much of central California had become over-run with thick smoke.

A comparison of AWIPS-II images of Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR image at 09:18 UTC or 2:18 AM local time (below) revealed the bright glow of the large fire complex, along with the large fire “hot spot” signature (black to yellow to red color enhancement).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm shortwave IR images during the overnight hours (just after 2 AM local time) on 17 and 18 September (below) showed the dramatic northeastward advance of the fire hot spot signature during that 24-hour period. Smoke from the fire was reducing the surface visibility to 3-4 miles as far to the northeast as Lovelock (KLOL) and Fallon (KNFL) in Nevada.

Suomi NPP VIIRS 3.74 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm shortwave IR images

Long-range transport of Canadian wildfire smoke

July 8th, 2014

GOES-15 (top) and GOES-13 (bottom) 0.63 µm visible channel images [click to play animation]

GOES-15 (top) and GOES-13 (bottom) 0.63 µm visible channel images [click to play animation]

On 08 July 2014 a comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (above; click image to play animation; also available as an MP4 movie file) showed the southward and southeastward transport of dense smoke from wildfires that were burning in the Northwestern Territories of Canada. Over the Lower 48 states, the leading edge of the smoke made it as far south as Iowa and northern Illinois. The bulk of the dense smoke was aloft, but at the surface the visibility was reduced to 3-5 miles at some locations in North Dakota.

The above example serves as a good demonstration of the principle of “forward scattering”: the smoke was more evident on visible imagery from GOES-15  early in the day (as the sun was rising), and more evident on visible imagery from GOES-13 later in the day (as the sun was setting).

Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server (below) showed the areal coverage of the hazy pall of smoke on 06 July, 07 July, and 08 July.

Suomi NPP VIIRS true-color images

Suomi NPP VIIRS true-color images

The IDEA-I forward airmass trajectory model applied to targets of high Aerosol Optical Depth (AOD) which were detected by the Terra MODIS instrument over Canada on 08 July are shown below. Such a tool can be used as an aid in air quality forecasting.

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

===== 09 July Update =====

The Terra MODIS AOD product (below; click to play animation) indicated that the leading edge of the Canadian wildfire smoke had advanced as far southward as northwestern Missouri. The bulk of the highest AOD values over the Dakotas was forecast to be transported slowly east-northeastward toward the Great Lakes region.

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

IDEA-I MODIS Aerosol Optical Depth and forward trajectories (click to play animation)

Cyclonic transport of fire smoke over the Gulf of Alaska

May 21st, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) showed the cyclonic transport of smoke across the Gulf of Alaska on 20 May 2014. The source of the smoke was the Funny River Fire that was burning on the Kenai Peninsula of south-central Alaska, near Soldotna. The fire quickly grew to 20,000 acres in about 24 hours.

The curved smoke plume was also quite evident on 3 separate Suomi NPP VIIRS 0.7 µm Day/Night Band images (below). Smoke was reducing the surface visibility as low as 3 miles at Homer (station identifier PAHO).

Suomi NPP VIIRS 0.7 µm Day/Night Band images

Suomi NPP VIIRS 0.7 µm Day/Night Band images

Even though patchy clouds covered the Kenai Peninsula region around 13 UTC, the fire “hot spots” (black to yellow to red color enhancement) were still detectable on the VIIRS 3.74 µm shortwave IR image (below).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR channel images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR channel images

Southern California wildfires

May 15th, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

With an ongoing extreme to exceptional drought, hot temperatures (daily high temperatures along the coastal areas as high as 106º F at John Wayne Airport) combined with strong offshore Santa Ana winds (gusting as high as 87 mph at Big Black Mountain) conspired to create an environment favorable for wildfires across southern California and northern Baja California on 14 May 2014. McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) showed a number of smoke plumes streaming off the coast during the day. Note the brief appearance of a cluster of bright white pixels on the 18:00 UTC image, just north of the California/Baja California border — this a signal of sunlight being reflected off of large solar panel arrays in that area.

The side-by-side comparison of GOES-15 (GOES-West) and GOES-13 (GOES-East) 0.63 µm visible channel images (below) showed that with a lowering sun angle at the end of the day, the smoke plumes began to become more difficult to identify on GOES-15 images (left); on the other hand, thanks to the benefit of a favorable forward scattering angle, the areal coverage of the smoke plumes stood out very well on GOES-13 images (right). The enhancements are the same on both sets of images.

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images

GOES-15 (left) and GOES-13 (right) 0.63 µm visible channel images

A 375-meter resolution Suomi NPP VIIRS true-color Red/Green/Blue (RGB) image visualized using the SSEC RealEarth web map server (below) showed these smoke plumes with great clarity at 20:25 UTC or 1:25 PM local time.

Suomi NPP VIIRS true-color RGB image

Suomi NPP VIIRS true-color RGB image

As the larger fires continued to burn into the subsequent overnight hours, their hot thermal signature could be detected on AWIPS images of 4-km resolution GOES-15 3.9 µm shortwave IR channel data (below; click image to play animation).

GOES-15 3.9 µm shortwave IR images (click to play animation)

GOES-15 3.9 µm shortwave IR images (click to play animation)

A nighttime comparison of a 375-meter resolution Suomi NPP VIIRS 3.74 µm shortwave IR image with the corresponding 750-meter resolution VIIRS Day/Night Band image (below) showed a prominent fire hot spot (yellow to red pixels) on the shortwave IR image between San Diego (KSAN) and Camp Pendleton (KNFG), along with light gray signature of the narrow, fresh smoke plume that was being blown off the coast from that fire on the Day/Night Band image. At the time of the image, smoke was restricting the surface visibility to 5 miles at Camp Pendleton. Farther offshore, reflected moonlight was helping to show the location of smoke that had spread out over the adjacent waters of the Pacific Ocean from the previous day of burning.

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 3.74 µm shortwave IR and 0.7 µm Day/Night Band images

Finally, a demonstration of the importance of higher spatial resolution for accurate fire hot spot detection: on the comparison of 375-meter resolution Suomi NPP VIIRS 3.74 µm and 4-km resolution GOES-15 3.9 µm shortwave IR images (below), note that although the size of the fire “hot spot” was smaller on the VIIRS image, the highest IR brightness temperature was 54.5º C (compared to 48.0º C on the GOES-15 image). In addition, the two smaller fires burning in northern Baja California were not detected on the GOES-15 image.

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images

Suomi NPP VIIRS 3.74 µm and GOES-15 3.9 µm shortwave IR images