Smoky hurricane

Smoky hurricane

16 September 2020 10:00–15:00 UTC

Smoky hurricane
Smoky hurricane

A large smoke cloud was sucked into Hurricane Paulette, changing microphysical properties of associated cloud bands.

Last Updated

22, October 2020

By Ivan Smiljanic (CGI)

Hurricane season 2020 is provided not only high number of Tropical Cyclones, but also rarely seen large-scale smoke intrusion into the cyclonic system.

Large-scale advection of smoke from the fires in California and Oregon met the path of hurricane Paulette. A low pressure system pulled the smoke in, setting up the conditions for more special cloud formation — a type of DIBS (Dust‐Infused Baroclinic cyclone Storm) cloud, this time seeded with smoke rather than dust particles. The mixture of smoke and water/ice particles gave birth to smaller cloud particles, longer lasting high ice clouds and more granular texture of cloud tops.

 GOES-17 GoeColor RGB, 16 September, 12:00 UTC. Credit: CIRA/RAM
Figure 1: GOES-17 GoeColor RGB, 16 September, 12:00 UTC. Credit: CIRA/RAM
 

It appears that smoke, unlike dust, produces a finer granular cloud structure. The size of individual cloud crystals also seemed to not be very small. However, comparing two contemporary hurricanes, Teddy and Paulette, one can notice smoother cloud tops with a sort of cirrus veil persisting aloft. Also in the Convection RGB Paulette's cloud bands take on more yellow hues (generally, not by looking at isolated smaller cloud patches), a sign of smaller cloud particles.

Image comparison

Natural Colour RGB image compare1
compare2
 

Figure 2: Comparison of between hurricane Paulette and Teddy, GOES-16 Convection RGB and Natural Colour RGB products, 16 September, 12:00 UTC.

Looking closer, through 500 m resolution of the ABI VIS0.64 channel, the cloud bands appear more 'milky', having a texture similar to whipped cream (Figure 3 and 4).

 GOES-16 VIS0.64 channel with resolution of 500 m, 16 September 2020, 14:00 UTC
Figure 3: GOES-16 VIS0.64 channel with resolution of 500 m, 16 September 2020, 14:00 UTC
 
 GOES-16 VIS0.64 channel with resolution of 500 m, 16 September 2020, 15:00 UTC
Figure 4: GOES-16 VIS0.64 channel with resolution of 500 m, 16 September 2020, 15:00 UTC
 

The hurricane's cirrus outflow also took on a prominent shape – showing very persistent, linear cirrocumulus formations.

 GOES-16 VIS0.64 channel with resolution of 500m, 16 September 2020, 12:00 UTC
Figure 5: GOES-16 VIS0.64 channel with resolution of 500m, 16 September 2020, 12:00 UTC
 

Long-distance smoke transport was happening in the higher levels of atmosphere, detected also by NIR1.3 ABI channel imagery. This channel is ‘blind’ to any particle reflection taking place in the lower troposphere (roughly lower than 500 hPa), due to water vapour absorption in around the 1300 nm spectral region. Reflectance range of this channel needs to be enhanced down to only 0-1 % for the full extent of smoke to be seen, even 0-3 % range is not completely sufficient for that (comparison in Figure 6).

Image comparison

NIR1.3 channel, range 0-3% compare1
compare2
 

Figure 6: GOES-16 NIR1.3 channel, range 0-1% (0-3% for background image), 16 September 12:00 UTC.

 

Previous case studies

Extensive DIBS in the deformation zone (18 April 2020)