Tropical Storm Danny in the eastern Atlantic Ocean

August 19th, 2015
GOES-13 10.7 µm IR images [click to play animated GIF]

GOES-13 10.7 µm IR images [click to play animated GIF]

The first tropical storm of the season in the eastern Atlantic (Ana, Bill and Claudette all formed over the western Atlantic) has formed from a cluster of thunderstorms that emerged from Africa. The multi-day animation, above, from GOES-13, shows the steady progress of the disorganized system across the eastern Atlantic basin. Visible Imagery from GOES-13 and Meteosat-10, below, from the morning of 19 August, show the system near 40 W. The cyclonic curvature to the clouds is apparent; identification of the center in infrared imagery, below, is more difficult. Convection to the east of Danny has colder cloud top temperatures.

Meteosat-10 0.6 µm Visible Imagery (Top, 1200 UTC) and GOES-13 0.63 µm Visible imagery (Bottom, 1145 UTC) on 19 August 2015 [click to enlarge]

Meteosat-10 0.6 µm Visible Imagery (Top, 1200 UTC) and GOES-13 0.63 µm Visible imagery (Bottom, 1145 UTC) on 19 August 2015 [click to enlarge]

Meteosat-10 10.8 µm Infrared Imagery (Top, 1200 UTC) and GOES-13 10.7 µm Infrared imagery (Bottom, 1145 UTC) on 19 August 2015 [click to enlarge]

Meteosat-10 10.8 µm Visible Imagery (Top, 1200 UTC) and GOES-13 10.7 µm Visible imagery (Bottom, 1145 UTC) on 19 August 2015 [click to enlarge]

ASCAT Winds with GOES-13 Water Vapor Imagery (6.5 µm), 0100 UTC 19 August 2015 [click to enlarge]

ASCAT Winds with GOES-13 Water Vapor Imagery (6.5 µm), 0100 UTC 19 August 2015 [click to enlarge]

ASCAT winds from 0100 UTC on 19 August 2015 (above) show a compact circulation center with winds of 40 knots just north of 10 N and east of 40 W.

Saharan Air Layer Tracking Product [click to play animated GIF]

Saharan Air Layer Tracking Product [click to play animated GIF]

A persistent impediment to Tropical Cyclone initiation in the eastern Atlantic this year has been widespread Saharan Air Layer dust. The one-day animation, above (taken from this website), shows the SAL persists over the Atlantic; Danny has formed just to the south. Wind shear over Danny at present is weak (see below [source]), and slow strenghtening is expected as Danny approaches the Caribbean.

Mid-level Wind Shear [click to enlarge]

Mid-level Wind Shear [click to enlarge]

The Discussion from the National Hurricane Center at 0900 UTC on 19 August included this phrase: “The center is difficult to locate on infrared images,…” The Day Night Band from VIIRS on Suomi NPP can sometimes be used to locate low-level circulation centers of tropical systems. This relies on the presence of moonlight, however, and when Suomi NPP overflew Danny just before 0500 UTC on 19 August, the moon was below the horizon. Thus, the Day Night Band, below (Courtesy of William Straka) gave very little information.

VIIRS 10.35 µm Infrared Imagery and 0.70 µm Visible Imagery, 0441 UTC 19 August 2015 [click to enlarge]

VIIRS 10.35 µm Infrared Imagery and 0.70 µm Visible Imagery, 0441 UTC 19 August 2015 [click to enlarge]

More information on Danny is available at the CIMSS Tropical Weather Website. Consult the National Hurricane Center for the latest updates and official forecasts.

GOES-14 SRSO-R: central Montana wildfire

August 15th, 2015

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm shortwave IR images [click to play MP4 animation]

GOES-15 (left), GOES-14 (center), and GOES-13 (right) 3.9 µm shortwave IR images [click to play MP4 animation]

A comparison of 4-km resolution GOES-15 (GOES-West), GOES-14, and GOES-13 (GOES-East) 3.9 µm shortwave infrared images (above; click to play MP4 animation; also available as a 9.4 Mbyte animated GIF) showed the development and evolution of the “hot spot” (dark black to yellow to red color enhancement) associated with a small wildfire that formed near the border of Fergus and Petroleum counties in central Montana during the afternoon hours on 15 August 2015. With GOES-15 Routine Scan mode “SUB-CONUS” sectors, images were available up to 6 times per hour (at :00, :11, :15, :30, :41, and :45); with GOES-13 in Rapid Scan Operations (RSO) mode, images were available up to 8 times per hour (at :00, :07, :15, :25, :30, :37, :45, and :55). The GOES-14 satellite had been placed into Super Rapid Scan Operations for GOES-R (SRSO-R) mode, providing images at 1-minute intervals to emulate what will be available with mesoscale sectors from the ABI instrument on GOES-R.

For the central Montana wildfire, the first unambiguous signature of a darker black wildfire hot spot began to appear on each satellite after about 1945 UTC, with the first color-enhanced pixels (signifying a shortwave IR brightness temperature of 331.9 K) showing up on the 2026 UTC GOES-14 image. The hottest fire pixel  on the GOES-15 images was 336.5 K at 2130 UTC, while the hottest fire pixel on GOES-13 images was 329.8 K at 2125 UTC. From 2120 to 2130 UTC, the hottest GOES-14 fire pixels were 341.2 K (the saturation temperature of the 3.9 µm detectors on that satellite).

With the finer spatial resolution of the shortwave IR detectors on the polar-orbiting MODIS (1-km) and VIIRS (375-meter) instruments, a fire hot spot was first detected on the 1857 UTC VIIRS image (below).

Terra/Aqua MODIS and Suomi NPP VIIRS 3.7 µm shortwave IR images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS 3.7 µm shortwave IR images [click to enlarge]

Eruption of the Cotopaxi volcano in Ecuador

August 14th, 2015

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images [click to play animation]

GOES-13 visible (0.63 µm) images (above; click to play animation) displayed distinct dark-gray ash plumes from 2 separate daytime eruptions of the Cotopaxi volcano in Ecuador on 14 August 2015 (there was also an initial eruption that occurred during the preceding nighttime hours). The asterisk near the center of the images marks the location of the volcano summit. Volcanic ash fall was observed in the capitol city of Quito (station identifier SEQU, located about 50 km or 30 miles north of the volcano), and some flights were diverted due to the volcanic ash cloud.

The corresponding GOES-13 infrared (10.7 µm) images (below; click image to play animation) showed that cloud-top IR brightness  temperatures were as cold a -53º C (orange color enhancement) at 1915 UTC.

GOES-13 infrared (10.7 µm) images [click to play animation]

GOES-13 infrared (10.7 µm) images [click to play animation]

The volcanic cloud features were also easily tracked on GOES-13 water vapor (6.5 µm) images (below; click image to play animation). In fact, note how the signature in the water vapor imagery is more distinctly seen for a longer period of time than on the 10.7 µm infrared imagery.

 GOES-13 water vapor (6.5 µm) images [click to play animation]

GOES-13 water vapor (6.5 µm) images [click to play animation]

The tan-colored volcanic ash cloud was also evident on Aqua MODIS and Suomi NPP VIIRS true-color Red/Green/Blue (RGB) imagery (below), as viewed using the SSEC RealEarth web map server.

Aqua MODIS true-color images [click to enlarge]

Aqua MODIS true-color images [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]

Suomi NPP VIIRS true-color image [click to enlarge]

A comparison of Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images is shown below (courtesy of William Straka, SSEC). The coldest cloud-top IR brightness temperature was -72.7º C.

Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images [click to enlarge]

Suomi NPP VIIRS visible (0.64 µm) and infrared (11.45 µm) images [click to enlarge]

Explosion in Tianjin, China

August 12th, 2015

Himawari-8 (3.9 µm, top), MTSAT-2 (3.75 µm, middle) and COMS-1 (3.75 µm, bottom) shortwave infrared imagery, times as indicated [click to animate]

Himawari-8 (3.9 µm, top), MTSAT-2 (3.75 µm, middle) and COMS-1 (3.75 µm, bottom) shortwave infrared imagery, times as indicated [click to animate]

A storage facility in Tianjin, China exploded shortly after 1500 UTC on 12 August 2015 (media story). Himawari-8, MTSAT-2 and COMS-1 all viewed the explosion that generated a strong thermal signature in the shortwave infrared band (3.75 µm – 3.9 µm). The animation above shows the benefit of Himawari-8’s speedier scanning mode: the smoke clouds that emanate from the explosion are easily traced, and data gaps when Full Disk images are being scanned (around 1800 UTC) are not present. Superior spatial resolution of Himawari-8 infrared channels (2-km, compared to 4-km for COMS-1 and MTSAT-2) means hotter brightness temperatures are sensed as well. The fact that smoke resulting from the explosion was seen spreading northeastward, southeastward, and southwestward was due to a marked shift in wind direction with height, as seen in the nearby Beijing rawinsonde report.

The explosion exhibted a signal in other Himawari-8 AHI bands as well. Band 5, at 1.6 µm and Band 6, at 2.3 µm are shown below (animations courtesy of William Straka, CIMSS); Similar animations are available for 3.9 µm, 6.2 µm (very faintly visible in this upper tropospheric water vapor channel), 7.0 µm, 7.3 µm and 8.6 µm and 10.35 µm.

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to enlarge]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

Himawari-8 1.6 µm near-Infrared Imagery, times as indicated [click to animate]

A view of Himawari-8 shortwave IR imagery using the SSEC RealEarth web map server is shown below. In addition, an animation of Himawari-8 true-color images showing the dark smoke plume can be seen here.

Himawari-8 shortwave IR (3.9 um) images, displayed using RealEarth [click to enlarge]

Himawari-8 shortwave IR (3.9 um) images, displayed using RealEarth [click to enlarge]


========================== Added 14 August 2015 ===================

Suomi NPP VIIRS Day/Night Band (0.70 um) visible images on 9 August (before explosion) and 13 August (after explosion) [click to enlarge]

Suomi NPP VIIRS Day/Night Band (0.70 um) visible images on 9 August (before explosion) and 13 August (after explosion) [click to enlarge]

The Suomi NPP satellite overflew Tianjin before and after the explosion; VIIRS Day/Night Band images afford views that suggest power outages around the explosion site.