Hurricane Teddy and wildfire smoke

September 22nd, 2020 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed that the large circulation of Hurricane Teddy (downgraded from a Category 2 to a Category 1 storm at 18 UTC) was drawing hazy filaments of smoke — likely originating from wildfires in the western US — southward from eastern Canada and New England, carrying it across the far western Atlantic Ocean on 22 September 2020. Also of interest (early in the animation) were the narrow fingers of river valley fog across parts of New York, Pennsylvania, Maryland, West Virginia and Virginia.

Although the size of Teddy’s cloud shield was still fairly large, a DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC from the CIMSS Tropical Cyclones site (below) showed that no organized core of deep convection remained as the storm began to move across colder waters (Sea Surface Temperature | Ocean Heat Content) and encounter a more hostile environment of increasing deep-layer wind shear.

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

DMSP-17 SSMIS Microwave (85 GHz) image at 2217 UTC [click to enlarge]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

GOES-16 CIMSS Natural Color RGB images, with and without an overlay of Aerosol Optical Depth [click to play animation | MP4]

A larger-scale view of GOES-16 CIMSS Natural Color RGB images — with and without an overlay of Aerosol Optical Depth (above) showed that an elongated plume of smoke stretched westward from New York and Pennsylvania to parts of Wisconsin, Illinois and Iowa. Upward-looking lidar data from the University of Wisconsin – Madison (below) depicted a thick layer of smoke between altitudes of 2-6 km.

Plots of lidar backscatter and depolarization from 12 UTC o n 22 September to 00 UTC on 23 September [click to enlarge]

Plots of lidar backscatter (top) and depolarization (bottom) from 12 UTC on 22 September to 00 UTC on 23 September [click to enlarge]

Northern California’s Bear Fire produces a pyrocumulonimbus cloud

September 9th, 2020 |

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed the formation of a pyrocumulonimbus (pyroCb) cloud over the Bear Fire (part of the North Complex) in Northern California on 09 September 2020. The coldest cloud-top infrared brightness temperatures were -61.4ºC; no GLM-detected lightning activity was seen with this pyroCb. 

A comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images (below) displayed the initial 2 pyroCb cloud pulses shortly after their formation. Side-illumination from the Moon (which was in the Waning Gibbous phase, at 59% of Full) allowed for a distinct shadow to be cast northwest of the colder/taller pyroCb pulse — and the pyroCb clouds exhibited a darker appearance than the layer of low-altitude smoke to the west, likely due to very high amounts of fresh smoke contained within the rapidly-rising cloud turrets.

Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

A toggle between time-matched Infrared Window images of the Bear Fire pyrocumulonimbus cloud from Suomi NPP (SNPP) and GOES-17 (below) highlighted the differences in spatial resolution — 375-m with SNPP VIIRS, vs 2-km (at satellite sub-point) with GOES-17 ABI — and the parallax displacement inherent with GOES-17 imagery at that location (17 km for a 15.2-km tall cloud top). The coldest cloud-top infrared brightness temperature was -76.2ºC with SNPP, vs -59.9ºC with GOES-17 (identical color enhancements were applied to both images).

Infrared Window images from Suomi NPP (11.45 µm) and GOES-17 (11.45 µm) [click to enlarge]

Infrared Window images from Suomi NPP (11.45 µm) and GOES-17 (10.35 µm) [click to enlarge]

GOES-17 True Color Red-Green-Blue (RGB) images created using Geo2Grid (below) showed the southward drift of the high-altitude pyroCb cloud material during the day, along with widespread dense smoke that covered much of California at lower altitudes.

GOES-17 True Color RGB images [click to pay animation | MP4]

GOES-17 True Color RGB images [click to pay animation | MP4]

Pyrocumulonimbus cloud spawned by the Creek Fire in California

September 5th, 2020 |

GOES-17 “Red” Visible (0.64 µm, top left), GOES-17 Shortwave Infrared (3.9 µm, top right), GOES-17 Fire Temperature RGB + GLM Flash Extent Density(bottom left) and

GOES-17 “Red” Visible (0.64 µm, top left), Shortwave Infrared (3.9 µm, top right), Fire Temperature RGB + GLM Flash Extent Density (bottom left) and “Clean” Infrared Window (10.35 µm, bottom right) [click to play animation | MP4]

1-minute Mesoscale Domain Sector GOES-17 (GOES-West) “Red” Visible (0.64 µm), GOES-17 Shortwave Infrared (3.9 µm), Fire Temperature Red-Green-Blue (RGB) + GLM Flash Extent Density (FED) and “Clean” Infrared Window (10.35 µm) images (above) showed the formation of a pyrocumulonimbus (pyroCb) cloud created by the Creek Fire in Central California on 05 September 2020. The appearance of a few brief GLM FED pixels (2026 UTC | 2117 UTC) indicated that this pyroCb cloud was producing lightning; the coldest cloud-top infrared brightness temperatures were -56.3ºC. The pyroCb developed after the Creek Fire made an explosive run to the north — and the pyroCb also spawned two “fire tornadoes”, which were rated EF2 and EF1 (Wildfire Today).

A comparison of time-matched Infrared Window images of the Creek Fire pyrocumulonimbus cloud from Suomi NPP (SNPP) and GOES-17 (below) highlighted differences in spatial resolution — 375-m with SNPP, vs 2-km (at satellite sub-point) with GOES-17 — and parallax displacement inherent with GOES-17 imagery at that location (17 km for a 15.2-km tall cloud top). The coldest cloud-top infrared brightness temperatures were -71.0ºC with SNPP, vs -55.5ºC with GOES-17. Identical color enhancements were applied to both images.

Infrared Window images from Suomi NPP and GOES-17 [click to enlarge]

Infrared Window images from Suomi NPP (11.45 µm) and GOES-17 (10.35 µm) [click to enlarge]

Several hours later, a nighttime comparison of Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images of the Creek Fire at 0935 UTC or 2:35 am PDT (below) showed the bright glow of the large fire, with several small but very hot fires continuing to burn along its periphery — and a few pyrocumulus clouds were developing along the western/southwestern edge. Along the northeastern edge of the fire signature, outlined in blue, is the Mammoth Pool Reservoir — where over 200 people needed to be airlifted from a campground after the only exit road was cut off by the fast-moving fire (media report).

Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images

Suomi NPP VIIRS Day/Night Band (0.7 µm), Shortwave Infrared (3.74 µm) and Infrared Window (11.45 µm) images [click to enlarge]

Long-range transport of California wildfire smoke across the Upper Midwest

August 24th, 2020 |

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 True Color RGB images [click to play animation | MP4]

GOES-16 (GOES-East) True Color Red-Green-Blue (RGB) images created using Geo2Grid (above) revealed the hazy signature of dense smoke aloft moving eastward across much of the Upper Midwest on 24 August 2020 — smoke that had been transported from large wildfires burning in California.

Images of 532 nm and 1064 nm lidar attenuated backscatter collected and processed by the University of Wisconsin Lidar Group at Madison from 00 UTC on 24 August to 00 UTC on 25 August (below) indicated that this smoke existed within altitudes between 2 km and 6 km.

532 nm and 1064 nm lidar attenuated backscatter during 24 August at Madison, Wisconsin [click to enlarge]

532 nm and 1064 nm lidar attenuated backscatter over Madison, Wisconsin [click to enlarge]

CIMSS Natural Color RGB images with plots of Pilot Reports are shown below. While this “simple” RGB does not depict the haziness of the smoke as well as the True Color RGB images above — which are corrected for the effect of Raleigh scattering — s subtle smoke signature was still apparent. Not many of the available Pilot Reports (PIREPs) explicitly mentioned any effects of the smoke, but one 1955 UTC PIREP indicated a reduction to Marginal Visual Flight Rules (MVFR, visibility of 3-5 miles) at at altitude of 11,500 feet (3.5 km).

CIMSS Natural Color RGB images, with plots of Pilot Reports [click to play animation | MP4]

CIMSS Natural Color RGB images, with plots of Pilot Reports [click to play animation | MP4]