CIMSS Satellite Blog, CIMSS

Pyrocumulonimbus clouds in Australia

By Scott Bachmeier • 1 February 2020

2.5-miute Rapid Scan JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.4 µm) images (above) showed the formation of 2 small, fairly short-lived pyrocumulonimbus (pyroCb) clouds spawned by large, hot bushfires in southern New South Wales, Australia on 01 February 2020. The pyroCb clouds developed... Read More

Himawari-8 “Red” Visible (0.64 µm, left), Shortwave Infrared (3.9 µm, center) and Infrared Window (10.4 µm, right) images [click to play animation | MP4]

2.5-miute Rapid Scan JMA Himawari-8 “Red” Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.4 µm) images (above) showed the formation of 2 small, fairly short-lived pyrocumulonimbus (pyroCb) clouds spawned by large, hot bushfires in southern New South Wales, Australia on 01 February 2020. The pyroCb clouds developed in advance of an approaching cold front (surface analyses), exhibiting 10.4 µm cloud-top infrared brightness temperatures in the -40 to -49ºC range (shades of blue). The first pyroCb formed at at 0311 UTC to the northeast of Cooma (YCOM), with the second formed at 0559 UTC just southwest of Merimbula (YMER).

NOAA-20 VIIRS True Color Red-Green-Blue (RGB) and Infrared Window (11.45 µm) images at 0426 UTC as viewed using RealEarth (below) revealed cloud-top infrared brightness temperatures near -60ºC (darker red enhancement).

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 042 UTC [click to enlarge]

NOAA-20 VIIRS True Color RGB and Infrared Window (11.45 µm) images at 0426 UTC [click to enlarge]

A toggle between Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 1454 UTC or 1:54 am AEDT (below) displayed the nighttime glow and hot thermal signatures of large bushfires south and southeast of Canberra.

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 1454 UTC [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.7 µm) and Shortwave Infrared (3.74 µm) images at 1454 UTC (credit: William Straka, CIMSS) [click to enlarge]

View only this post Read Less

Interesting circular contrail over South Dakota

By Scott Bachmeier • 29 January 2020

Multi-panel images of all 16 ABI spectral bands from GOES-16 (GOES-East) (above) revealed an interesting circular contrail over northeastern South Dakota on 29 January 2020. A signature of this contrail was evident in all 16 bands — visible, near-infrared and infrared. This feature was likely formed by a military aircraft performing training... Read More

Multi-panel images of all 16 ABI spectral bands from GOES-16 [click to play animation | MP4]

Multi-panel images of all 16 ABI spectral bands from GOES-16 (GOES-East) (above) revealed an interesting circular contrail over northeastern South Dakota on 29 January 2020. A signature of this contrail was evident in all 16 bands — visible, near-infrared and infrared. This feature was likely formed by a military aircraft performing training exercises over the area.

A sequence of GOES-16 ABI spectral band images covering that same 1751-2001 UTC time period (below) provided a larger view of the circular contrail — whose diameter was about 10-12 miles — along with a linear contrail located about 30 miles to the southwest.

Sequence of GOES-16 ABI spectral band images [click to play animation | MP4]

A toggle between GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images at 1911 UTC (below) showed that the darker signature seen in the Visible imagery was a shadow cast by the higher-altitude contrail onto the top of the low-altitude stratus clouds. A similar northwestward shadow offset (of about 5 miles) was apparent with the linear contrail feature.

GOES-16 “Red” Visible (0.64 µm) and Near-Infrared “Cirrus” (1.37 µm) images at 1911 UTC [click to enlarge]

The southwestward shift of the higher-altitude contrail (with respect to the surface shadow) was not due to parallax — this webapp shows that the direction of parallax shift over that region would be northwestward for cloud features at altitudes of 15,000 feet and 30,000 feet (below).

Parallax correct vectors (green arrows) and magnitudes (red. in km) for cloud features at 15,000 feet and 30,000 feet over the CONUS domain [click to enlarge]

Plots of rawinsonde data from Aberdeen, South Dakota (below) showed an increase in moisture during the day within the 500-300 hPa layer — due to its relatively slow southeastward propagation, the circular contrail likely existed within the lower portion of that layer (where wind speeds were less).

Plots of rawinsonde data from Aberdeen, South Dakota [click to enlarge]

A signature of the circular contrail was seen in all 3 of the GOES-16 Water Vapor spectral bands — weighting functions derived using rawinsonde data from Aberdeen, South Dakota (below) showed either primary or secondary peaks within the 500-300 hPa layer.

GOES-16 Water Vapor weighting functions derived using rawinsonde data from Aberdeen, South Dakota [click to enlarge]

Thanks go out to Jay Trobec (@trobec), KELOLAND TV in Sioux Falls, for alerting us about this interesting example.

View only this post Read Less

Stratospheric smoke from Australian bushfires

By Scott Bachmeier • 24 January 2020

GOES-16 (GOES-East) Near-Infrared “Cirrus” (1.37 µm) images during the 19-24 January 2019 period (above) showed a semi-circular pall of smoke that originated from Australian bushfires — outbreaks of pyrocumulonimbus clouds that occurred in late December 2019 and early January 2020 injected large amounts of smoke into the lower stratosphere, and this smoke drifted eastward across... Read More

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, 19-24 January 2019 [click to play animation | MP4]

GOES-16 (GOES-East) Near-Infrared “Cirrus” (1.37 µm) images during the 19-24 January 2019 period (above) showed a semi-circular pall of smoke that originated from Australian bushfires — outbreaks of pyrocumulonimbus clouds that occurred in late December 2019 and early January 2020 injected large amounts of smoke into the lower stratosphere, and this smoke drifted eastward across the South Pacific Ocean. The 1.37 µm spectral band does a good job at detecting light scattered by airborne particles such as ice crystals, smoke, volcanic ash, dust, etc.; the areal extent of the smoke was most apparent approaching sunset on each day, due to enhanced forward scattering.

CALIPSO satellite CALIOP lidar data indicated that this smoke often resided at altitudes in the 18-24 km range — one example from 21 January can be seen here. 12-hourly GOES-16 Cirrus images with plots of GFS model 70 hPa wind barbs during the 20-24 January 2019 period (below) showed that winds at the 70 hPa pressure level were generally light.

GOES-16 Near-Infrared “Cirrus” (1.37 µm) images, with plots of GFS model 70 hPa wind barbs (knots), 20-24 January 2019 [click to enlarge]

As the stratospheric smoke feature was beginning to move over the Punta Arena, Chile area (station identifier SCCI), rawinsonde data from that site indicated that the wind speed at 70 hPa (18.5 km) was 18 knots (below).

Plot of rawinsonde data from Punta Arenas, Chile at 12 UTC on 24 January [click to enlarge]

View only this post Read Less

Gravity waves over the Gulf of Mexico and Florida

By Scott Bachmeier • 22 January 2020

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed a packet of gravity waves over the eastern Gulf of Mexico and southern Florida on 22 January 2020. Later time in the time period, there were isolated pilot reports of moderate turbulence in the vicinity of the waves... Read More

GOES-16 Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images, with pilot reports of turbulence [click to play animation | MP4]

GOES-16 (GOES-East) Low-level (7.3 µm), Mid-level (6.9 µm) and Upper-level (6.2 µm) Water Vapor images (above) showed a packet of gravity waves over the eastern Gulf of Mexico and southern Florida on 22 January 2020. Later time in the time period, there were isolated pilot reports of moderate turbulence in the vicinity of the waves (though it’s uncertain whether the gravity waves were directly responsible).

What caused these gravity waves to form and slowly propagate southeastward is also uncertain — earning this example its place in the “What the heck is this?” blog category. The SPC Mesoscale Analysis at 07 UTC (below) did show weak convergence of 300 hPa ageostrophic winds (dark blue oval) in the entrance region of a secondary jet streak “J” over the Gulf of Mexico — this convergence could have played a role in the gravity wave development.

SPC Mesoscale Analysis valid at 07 UTC, showing 300 hPa height, isotachs and ageostrophic winds [click to enlarge]

GOES-16 Derived Motion Winds (calculated using 6.9 µm imagery) in the vicinity of the gravity waves (below) had velocities in the 50-60 knot range at pressure levels of 370-380 hPa (0916 UTC).

GOES-16 Water Vapor (6.2 um) Derived Motion Winds [click to enlarge]

GOES-16 Water Vapor (6.9 µm) Derived Motion Winds [click to enlarge]

Also of note was the fact that the surface of southern Florida was sensed by GOES-16 Low-level Water Vapor imagery (below).

GOES-16 Low-level (7.3 µm) Water Vapor images, with pilot reports of turbulence [click to play animation | MP4]

With an unseasonably cold, dry air mass moving southward over the peninsula, the 7.3 µm water vapor weighting functions were shifted to lower altitudes at Miami and Key West (below) — this allowed the thermal contrast between relatively cool land surfaces and the surrounding warmer water to be seen in the 7.3 µm imagery.

GOES-16 weighting functions for the 7.3 µm (violet), 6.9 µm (blue) and 6.2 µm (green) Water Vapor spectral bands, calculated using 12 UTC rawinsonde data from Miami, Florida [click to enlarge]

GOES-16 weighting functions for the 7.3 µm (violet), 6.9 µm (blue) and 6.2 µm (green) Water Vapor spectral bands [click to enlarge]

GOES-16 weighting functions for the 7.3 µm (violet), 6.9 µm (blue) and 6.2 µm (green) Water Vapor spectral bands, calculated using 12 UTC rawinsonde data from Key West, Florida [click to enlarge]

In fact, at Key West the Total Precipitable Water value of 0.3 inch calculated from 12 UTC rawinsonde data (below) was a new record for the date/time (the previous record minimum value was 0.36 inch).

Climatology of Total Precipitable Water for the Key West, Florida rawinsonde site [click to enlarge]

View only this post Read Less

First
Previous
Go to Page:
Next
Last

Pyrocumulonimbus clouds in Australia

Interesting circular contrail over South Dakota

Stratospheric smoke from Australian bushfires

Gravity waves over the Gulf of Mexico and Florida

Search blog

Categories

Authors

Archive

Follow us on