GOES-14 0.63 µm Visible (top), 3.9 µm Shortwave Infrared (middle) and 10.7 µm Infrared Window (bottom) images, with surface reports plotted in yellow [click to play MP4 animation]
The Pioneer Fire
in central Idaho produced another pyroCumulonimbus (pyroCb) cloud on 21 August 2016
(the first was on 19 August
). GOES-14 was in SRSO-R
mode, and sampled the fire with 1-minute imagery (above; also available as a large 73 Mbyte animated GIF
) — a large smoke plume was evident on 0.63 µm Visible images as it moved eastward; large fire hot spots (red pixels)
were seen on 3.9 µm Shortwave Infrared images; on 10.7 µm Infrared Window images, the cloud-top IR brightness temperature cooled to -35º C (darker green enhancement)
between 2249-2307 UTC as it moved over Stanley Ranger Station (KSNY), not quite reaching the -40º C threshold to be classified as a pyroCb.
However, a 1-km resolution NOAA-19 AVHRR 10.8 µm Infrared Window image (below; courtesy of René Servranckx) revealed a minimum cloud-top IR brightness temperature of -48.3º C (dark green color enhancement).
NOAA-19 AVHRR 0.64 µm visible (top left), 3.7 µm shortwave IR (top right), 10.8 µm IR window (bottom left) and false-color RGB composite image (bottom right) [click to enlarge]
A larger-scale comparison of the NOAA-19 AVHRR visible, shortwave infrared and infrared window images is shown below.
NOAA-19 Visible (0.63 µm), Shortwave Infrared (3.7 µm) and Infrared Window (10.8 µm) images [click to enlarge]
===== 23 August Update =====
Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm) and 11.45-3.74 µm brightness temperature difference images [click to enlarge]
The Pioneer Fire continued to be very active on 22 August
(exceeding 100,000 acres in total burn coverage since its start on 18 July), sending a large amount of smoke northeastward (OMPS Aerosol Index
). During the following overnight hours, cold air drainage and the development of a boundary layer temperature inversion acted to trap a good deal of smoke in the Payette River valley to the west/southwest of Stanley KSNT. The active fire hot spots (black to yellow to red pixels)
were evident on nighttime (1032 UTC or 4:32 AM local time) images (above)
of Suomi NPP VIIRS Shortwave Infrared (3.74 µm) data, while illumination from the Moon (in the Waning Gibbous phase, at 69% of Full) showed the ribbon of smoke trapped in the valley (note that this signal was not due to fog, since it did not show up in the VIIRS 11.45-3.74 µm brightness temperature difference or “fog/stratus product”).
During the subsequent daytime hours of 23 August, 1-minute GOES-14 Visible (0.63 µm) images (below; also available as a large 114 Mbyte animated GIF) showed the gradual ventilation of smoke from the Payette River valley as the temperature inversion eroded and mixing via winds increased.
GOES-14 Visible (0.63 um) images, with plots of hourly surface reports [click to play MP4 animation]