Eruption of the Mount Pavlof volcano in Alaska

March 28th, 2016

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

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

A major eruption of the Mount Pavlof volcano on the Alaska Peninsula began shortly before 0000 UTC on 28 March, or 4:00 pm on 27 March Alaska time (AVO report), as detected by a thermal anomaly (or “hot spot”, yellow to red color enhancement) on Himawari-8 AHI Shortwave Infrared (3.9 µm) images (above). The hot spot decreased in size and intensity toward the later hours of the day, signaling a lull in the volcanic eruption.

It is interesting to note on a comparison of the 0000 UTC Himawari-8 and GOES-15 Shortwave Infrared (3.9 um) images the large difference in the magnitude of the thermal anomaly — even though the viewing angle was larger for Himawari-8, the superior spatial resolution (2 km at nadir, compared to 4 km with GOES-15) detected a hot spot with an Infrared Brightness Temperature (IR BT) that was 36.6 K warmer (below). The Infrared channels on the GOES-R ABI instrument will also have a 2 km spatial resolution.

Himawari-8 AHI (left) and GOES-15 Imager (right) 3.9 µm Shortwave Infrared images [click to enlarge]

Himawari-8 AHI (left) and GOES-15 Imager (right) 3.9 µm Shortwave Infrared images [click to enlarge]

With the aid of reflected light from the Moon (in the Waxing Gibbous phase, at 75% of Full), a nighttime view using the Suomi NPP VIIRS Day/Night Band (0.7 µm) from the SSEC RealEarth site (below) revealed the bright glow of the eruption, along with the darker (compared to adjacent meteorological clouds) volcanic ash cloud streaming northeastward. The corresponding VIIRS Shortwave Infrared (3.74 µm) image showed the dark black hot spot of the volcano summit.

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

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

The volcanic ash cloud continued moving in a northeastward direction, as seen in a sequence of GOES-15 Infrared Window (10.7 µm) and either Terra/Aqua MODIS or Suomi NPP VIIRS retrieved Volcanic Ash Height products from the NOAA/CIMSS Volcanic Could Monitoring site (below).

GOES-15 Infrared (10.7 µm) images, with Terra/Aqua MODIS and Suomi NPP VIIRS Ash Height products [click to play animation]

GOES-15 Infrared (10.7 µm) images, with Terra/Aqua MODIS and Suomi NPP VIIRS Ash Height products [click to play animation]

Due to the oblique satellite view angle, the shadow cast by the tall volcanic ash cloud was easily seen on the following early morning (Alaska time) Himawari-8 AHI Visible (0.64 µm) images (below). A closer view (courtesy of Dan Lindsey, RAMMB/CIRA) revealed overshooting tops and gravity waves propagating downwind of the eruption site.

Himawari-8 AHI Visible (0.64 um) images (click to play animation]

Himawari-8 AHI Visible (0.64 um) images (click to play animation]

A few select Pilot reports (PIREPs) are shown below, plotted on GOES-15 Infrared Window (10.7 µm) and Aqua MODIS Ash Height derived products. Numerous flights were canceled as the ash cloud eventually began to drift over Western and Interior Alaska (media report).

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um) image, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm) image, with METAR surface reports and Pilot reports [click to enlarge]

Aqua MODIS Ash Height product, with METAR surface reports and Pilot reports [click to enlarge]

Aqua MODIS Ash Height product, with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 um), with METAR surface reports and Pilot reports [click to enlarge]

GOES-15 Infrared Window (10.7 µm), with METAR surface reports and Pilot reports [click to enlarge]

A comparison of Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color Red/Green/Blue (RGB) images (below) showed the volcanic hot spot and the brown to tan colored ash cloud at 2141 UTC on 28 March. Significant ash fall (as much as 2/3 of an inch) was experienced at the village of Nelson Lagoon, located 55 miles northeast of Pavlof (media report).

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color RGB images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.74 µm), Day/Night Band (0.7 µm), and true-color RGB images [click to enlarge]

A comparison of the 3 Himawari-8 AHI Water Vapor bands (7.3 µm, 6.9 µm and 6.2 µm) covering the first 14 hours of the eruption from 0000 to 1400 UTC is shown below. Note that volcanic plume was best seen on the 7.3 µm images, which indicated that it began to move over the coast of Western Alaska after around 0600 UTC; this is due to the fact that the 7.3 µm band is not only a “water vapor absorption” band, but is also sensitive to high levels of SO2 loading in the atmosphere (as was pointed out in this blog post).

Himawari-8 AHI Water Vapor 7.3 µm (left), 6.9 µm (center) and 6.2 µm (right) images [click to play animation]

Himawari-8 AHI Water Vapor 7.3 µm (left), 6.9 µm (center) and 6.2 µm (right) images [click to play animation]

2 West Pacific storms, as seen using 3 Himawari-8 water vapor bands

March 19th, 2016

Himawari-8 Water Vapor images: 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) - [click to play MP4 animation]

Himawari-8 Water Vapor images: 6.2 µm (top), 6.9 µm (middle), and 7.3 µm (bottom) – [click to play MP4 animation]

The Himawari-8 AHI instrument has 3 water vapor bands, centered at 6.2 µm, 6.9 µm, and 7.3 µm. Images of these 3 water vapor bands (above; also available as a large 126 Mbyte animated GIF) showed the intensification of a mid-latitude cyclone as it moved east of Japan during the 17-19 March 2016 period. Surface analyses of this storm produced by the Ocean Prediction Center are shown below.

West Pacific surface analyses [click to play animation]

West Pacific surface analyses [click to play animation]

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Himawari-8 Water Wapor images: 7.3 µm (left), 6.9 µm (center), and 6.2 µm (right) - [click to play MP4 animation]

Himawari-8 Water Wapor images: 7.3 µm (left), 6.9 µm (center), and 6.2 µm (right) – [click to play MP4 animation]

Several days earlier (during 14-16 March), another storm just off the coast of Japan rapidly intensified to hurricane force as it moved north-northeastward toward the southern tip of the Kamchatka Peninsula. A comparison of the three Himawari-8 AHI water vapor bands (above; also available as a large 109 Mbyte animated GIF) depicted varying aspects of the storm evolution. The corresponding Ocean Prediction Center surface analyses are shown below.

West Pacific surface analyses [click to play animation]West Pacific surface analyses [click to play animation]

West Pacific surface analyses [click to play animation]

The GOES-R ABI instrument will have nearly identical water vapor bands; plots of their weighting functions (below, from this site) show that each of these 3 spectral bands senses radiation from different layers of the atmosphere. This example assumes a typical cold mid-latitude winter temperature/moisture vertical profile, with a satellite view angle (or “zenith angle”) of 45 degrees.

GOES-R ABI water vapor band weighting function plots

GOES-R ABI water vapor band weighting function plots

Severe Cyclone Emeraude in the Indian Ocean

March 17th, 2016

Advanced Dvorak Technique intensity plot for Cyclone Emeraude [click to enlarge]

Advanced Dvorak Technique intensity plot for Cyclone Emeraude [click to enlarge]

A plot of the Advanced Dvorak Technique intensity estimate for Cyclone Emeraude in the Indian Ocean (above) shows that the storm rapidly intensified to Category 4 intensity on 17 March 2016.

Himawari-8 AHI Visible (0.64 µm) and Infrared Window (10.4 µm) images (below; also available as a large 31-Mbyte animated GIF) revealed the formation of a well-defined eye during the day.

Himawari-8 Visible (0..64 µm, top) and Infrared Window (10.4 µm, bottom) images [click to play MP4 animation]

Himawari-8 Visible (0..64 µm, top) and Infrared Window (10.4 µm, bottom) images [click to play MP4 animation]

Nighttime images of Suomi NPP VIIRS Day/Night Band (0.7 µm) and Infrared Window (11.45 µm) data at 1859 UTC (below, courtesy of William Straka, SSEC) showed the ragged appearance of the eye at that time, with an isolated convective burst that had developed well west of the eye.

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

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

Solar eclipse shadow as seen from geostationary satellites

March 9th, 2016

Himawari-8 true-color images [click to play MP4 animation]

Himawari-8 true-color images [click to play MP4 animation]

The shadow of the total solar eclipse of 09 March 2016 was captured by a number of geostationary satellites, including JMA Himawari-8 (above; also available as either a large 140 Mbyte animated GIF, or a YouTube video: large) | small) and KMA COMS-1 (below). The Himawari-8 true-color Red/Green/Blue (RGB) images were created using the Simple Hybrid Contrast Stretch (SHCS) method by Yasuhiko Sumida, SSEC visiting scientist from JMA.

COMS-1 Visible (0.67 um) images [click to play animation]

COMS-1 Visible (0.67 um) images [click to play animation]

Toward the end of the eclipse, the shadow was also seen with NOAA GOES-15 (below) as it moved northwest and north of Hawai’i.

GOES-15 Visible (0.63 um) images [click to play animation]

GOES-15 Visible (0.63 um) images [click to play animation]

In addition, the eclipse shadow was captured with the Chinese satellites FY-2E and FY-2G (below).

FY-2E Visible (0.73 µm) images [click to enlarge]

FY-2E Visible (0.73 µm) images [click to enlarge]

FY-2G Visible (0.73 µm) images [click to enlarge]

FY-2G Visible (0.73 µm) images [click to enlarge]