CIMSS Satellite Blog

Himawari-8 “Red” Visible (0.64 µm) images [click to play animation | MP4]

Large bushfires burning in the southern portion of the state of Western Australia produced three pyroCumulonimbus (pyroCb) clouds on 01 March 2019. JMA Himawari-8 “Red” Visible (0.64 µm) images (above) showed that the pyroCb clouds drifted southeastward after formation.

Himawari-8 “Clean” Infrared Window (10.4 µm) images (below) further revealed the 3 distinct pyroCb pulses — 2 originating from the southernmost fire located near 29.5ºS / 124.4ºE, and a smaller one originating from a fire located farther to the northwest. Cloud-top infrared brightness temperatures cooled to the -60 to -65ºC range for the pair of larger pyroCbs (corresponding to the tropopause level on Perth rawinsonde data), with temperatures reaching -50ºC with the smaller northernmost pyroCb. Also apparent was a surge of cooler air moving northeastward behind a surface trough, whose arrival appeared to coincide with the pyroCb formation. A time series of surface data from Forrest (YFRT) clearly showed the arrival of the cool, moist air behind the trough.

Himawari-8 “Clean” Infrared Window (10.4 µm) images [click to play animation | MP4]

On Himawari-8 Shortwave Infrared (3.9 µm) images (below), the pyroCb clouds exhibited a warmer (darker gray) appearance compared to adjacent conventional cumulonimbus clouds — this is due to the fact that ice crystals ejected into the pyroCb anvils are smaller (due to their shorter residence time within the intense updrafts above the fires), and these smaller ice crystals are more effective reflectors of incoming solar radiation. The large flare-up of red-enhanced land during the day is due to highly reflective soils of the Great Victoria Desert that quickly become very hot.

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

from CIMSS Satellite Blog http://cimss.ssec.wisc.edu/goes/blog/archives/32125