25-year anniversary of the 1991 Mount Pinatubo eruption

June 15th, 2016

GMS-4 Infrared Window (11.5 µm) images [click to play animation]

GMS-4 Infrared Window (11.5 µm) images [click to play animation]

During the first 2 weeks of June 1991 the Mount Pinatubo volcano on the island of Luzon in the Philippines began to produce a series of eruptions, culminating in the climactic eruption beginning at 0227 UTC on 15 June. An animation of 5-km resolution GMS-4 Infrared Window (11.5 µm) images (above) spans the period from 1831 UTC on 12 June to 1831 UTC on 16 June, and showed the very large volcanic cloud following the 15 June eruption (the animation pauses at the 0230 UTC image on 15 June — just after the time of the major eruption). Also evident in the imagery was the westward movement of what became Category 3 Typhoon Yunya (known locally in the Philippines as Diding) toward Luzon. A larger-scale version of the animation is available here.

A closer view of the GMS-4 Infrared Window (11.5 µm) images (below) revealed interesting characteristics of the volcanic plume which penetrated the tropopause (which was at an air temperature of around -83º C, according to nearby rawinsonde reports) during the 3-8 hours following the onset of the 0227 UTC eruption. Note the initial appearance of a small area of very warm IR cloud-top IR brightness temperatures (-21.6º C at 0631 UTC, and -25.7º C at 0730 UTC) which then blossomed outward and became a westward-moving stratospheric plume that was notably warmer than the majority of the cold volcanic cloud canopy (which exhibited IR brightness temperatures in the -80º to -90º C range, denoted by the violet to yellow color enhancement).

GMS-4 Infrared Window (11.5 µm) images [click to enlarge]

GMS-4 Infrared Window (11.5 µm) images [click to enlarge]

———————————————————————————————————-

NOAA-10 AVHRR Infrared Window (10.8 µm), Visible (0.91 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

NOAA-10 AVHRR Infrared Window (10.8 µm), Visible (0.91 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

A higher-resolution (1.1-km) view of the post-eruption cloud was provided by NOAA-10 AVHRR images at 1034 UTC on 15 June (above). Even though it was just past sunset over the Philippines, the narrow stratospheric plume could be seen towering above the canopy of the main volcanic cloud (the plume was at a high enough altitude — estimated at a maximum of 40 km (reference 1 | reference 2) — to still be illuminated by sunlight). The summit of Pinatubo is located 8.7 miles/14 km west-southwest of what was then Clark Air Force Base (station identifier RPLC). On the 10.8 µm Infrared Window image, cloud-top gravity waves could be seen propagating radially outward from the overshooting top located above the volcano (which exhibited a minimum IR brightness temperature of -86º C, violet color enhancement). Note the much warmer IR brightness temperatures (as warm as -31º C, green color enhancement) associated with the stratospheric plume just off the west coast of Luzon. A closer view is available here.

About 10 hours prior to the climactic eruption, a volcanic ash cloud from one of the earlier eruptions was captured by NOAA-10 AVHRR images at 2329 UTC on 14 June (below). Around this same time it can be seen that Yunya was making landfall as a minimal-intensity typhoon along the eastern coast of Luzon. A closer view is available here.

NOAA-10 AVHRR Infrared Window (10.8 µm), Visible (0.91 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

NOAA-10 AVHRR Infrared Window (10.8 µm), Visible (0.91 µm) and Shortwave Infrared (3.7 µm) images [click to enlarge]

GOES-3 is being decommissioned

May 27th, 2016
GOES3_VIS_1545_18MAY1980

GOES-3 Visible Image from 18 May 1980 at 1545 UTC (Click to enlarge)

GOES-3 started service on 16 June 1978 and was the operational GOES-West satellite until the late 1980s. Having lost imaging capabilities, it started a second long life as a communications satellite; GOES-3 is currently the oldest operating satellite. Decommissioning will begin on 8 June and run for 15 days. If final decommissioning happens as planned on 23 June, GOES-3’s service life will be 38 years, 7 days.

GOES-3’s arguably most famous imagery occurred during the eruption of Mount St. Helens on 18 May 1980, shown above (click here for an animation of the eruption, courtesy of Barry Roth, SSEC; Tim Schmit, NOAA/ASPB also provided longer visible animations: MP4 | animated GIF).

A comparison of GOES-3 Visible (0.65 µm) and Infrared Window (11.5 µm) images, below, showed that a large portion of the volcanic cloud exhibited IR brightness temperatures of -60º C (dark red color enhancement) or colder as the feature moved rapidly eastward during the first 10 hours following the eruption. It is interesting to note that an “enhanced-V” or cold/warm (-65º/-47º C) thermal couplet signature was evident on the initial 1545 UTC Infrared image (zoom), as the volcanic ash cloud rapidly rose to an estimated altitude of 12 to 16 miles (20 to 27 km) above sea level.

GOES-3 0.65 µm Visible (top) and 10.7 µm Infrared Window (bottom) images [click to play animation]

GOES-3 0.65 µm Visible (top) and 11.5 µm Infrared Window (bottom) images [click to play animation]

Some early examples of full disk GOES-3 images (on 20 November 1978) are shown below, courtesy of Tim Schmit, NOAA/ASPB.

GOES-3 Visible (0.65 µm) and Infrared Window (11.6 µm) images [click to enlarge]

GOES-3 Visible (0.65 µm) and Infrared Window (11.6 µm) images [click to enlarge]

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 the 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]

Eruption of the Popocatépetl Volcano in Mexico

January 25th, 2016

Soumi NPP VIIRS true-color RGB images [click to enlarge]

Soumi NPP VIIRS true-color RGB images [click to enlarge]

The Popocatépetl Volcano in Mexico began erupting at 1546 UTC on 20 January 2016 (Washington VAAC message). The volcanic plume was evident on Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images on 23, 24, and 25 January, as viewed using the SSEC RealEarth web map server (above).

Nighttime images of Suomi NPP VIIRS Shortwave Infrared (3.9 µm), Longwave Infrared Window (11.45 µm), and Day/Night Band (0.7 µm) images at 0817 UTC on 25 January (below, courtesy of William Straka, SSEC) revealed the hot spot of the erupting volcano summit (orange pixels), and ample illumination from the Moon allowed the plume to be seen on the Day/Night Band image. The large areas of bright city lights from Mexico City and Pueblo (located northwest and southeast of Popocatépetl, respectively) are also very apparent on the Day/Night Band image.

Suomi NPP VIIRS Shortwave Infrared (3.9 µm), Longwave Infrared Window (11.45 µm), and Day/Night Band (0.7 µm) images [click to enlarge]

Suomi NPP VIIRS Shortwave Infrared (3.9 µm), Longwave Infrared Window (11.45 µm), and Day/Night Band (0.7 µm) images [click to enlarge]

A legacy product for use in the detection of volcanic ash plumes is the Infrared “Split-Window” (11-12 µm) brightness temperature difference product (below), which showed the plume streaming eastward to northeastward during the 24-25 January period.

Terra/Aqua MODIS and Suomi NPP VIIRS Infrared "Split Window" (11-12 µm) Brightness Temperature Difference product images [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Infrared “Split Window” (11-12 µm) Brightness Temperature Difference product images [click to enlarge]

Taking advantage of the multi-spectral imagery available from the MODIS and VIIRS instruments on the Terra/Aqua ans Suomi NPP satellites, quantitative products can be derived such as Ash Height, Ash Loading, Ash Effective Radius, and Ash Probability from the NOAA/CIMSS Volcanic Coud Monitoring (below).

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Height product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Height product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Loading product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Loading product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Effective Radius product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Effective Radius product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Probability product [click to enlarge]

Terra/Aqua MODIS and Suomi NPP VIIRS Volcanic Ash Probability product [click to enlarge]