Eruption of the Pavlof Volcano in Alaska

November 15th, 2014
Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

According to the Alaska Volcano Observatory, an eruption of the Pavlof Volcano began around 01:50 UTC on 13 November 2014. A comparison of nighttime images of Suomi NPP VIIRS 0.7 µm Day/Night Band (DNB) and 3.74 µm shortwave IR data at 13:07 UTC or 4:07 am local time on 14 November (above) showed the bright glow of the eruption on the DNB image, with the hottest pixel being 52º C (red color enhancement) on the shortwave IR image.

With the subsequent arrival of daylight, a break in the clouds allowed the faint volcanic plume to be observed on GOES-15 0.63 µm visible channel images (below; click image to play animation), drifting northwestward over the Bering Sea.

GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

At 22:02 UTC on 14 November, the radiometrically-retrieved maximum volcanic ash mass loading value was 1.8 tons per km2, the maximum ash height was 16.8 km, and the maximum ash mass effective radius was 7.81 µm (below).

MODIS volcanic ash mass loading, ash height, and ash mass effective radius products

MODIS volcanic ash mass loading, ash height, and ash mass effective radius products

About an hour later, the volcanic ash plume could be seen on a 23:03 UTC Suomi NPP VIIRS Day/Night Band image, with a maximum 3.74 µm shortwave IR brightness temperature of 46º C at the summit of the volcano (below).

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

Suomi NPP VIIRS 0.7 µm Day/Night Band and 3.74 µm shortwave IR images

The brown hue of the volcanic ash plume was very evident on Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server (below).

Suomi NPP VIIRS true-color RGB images

Suomi NPP VIIRS true-color RGB images

The intensity of the Pavlof eruption increased on 15 November, and a well-defined volcanic ash plume could be seen on GOES-15 0.63 µm visible channel images (below; click image to play animation). Pilot reports estimated that the top of the plume was as high as 38,000 feet.

GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

On a comparison of Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images at 22:45 UTC (below), the coldest cloud-top IR brightness temperature value was -55º C.

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

Suomi NPP VIIRS 0.64 µm visible channel and 11.45 µm IR channel images

At 22:29 UTC, the CLAVR-x POES AVHRR Cloud Top Temperature product indicated a minimum value of -54º C, with a maximum Cloud Top Height value of 9 km; the -54º C cloud top temperature corresponded to an altitude of around 29,000 feet or 8.7 km on the 16 November/00 UTC Cold Bay AK rawinsonde profile.

POES AVHRR Cloud Top Temperature and Cloud Top Height products

POES AVHRR Cloud Top Temperature and Cloud Top Height products

A Suomi NPP VIIRS true-color RGB image at 23:04 UTC (below) suggested that the volcanic plume consisted of a dense layer of tan-colored ash, with a layer of mostly ice cloud at the top of the plume.

Suomi NPP VIIRS true-color RGB image

Suomi NPP VIIRS true-color RGB image

Re-suspended volcanic ash from the Novarupta volcano in Alaska

September 29th, 2014
GOES-15 0.63 µm visible channel images (click to play animation)

GOES-15 0.63 µm visible channel images (click to play animation)

McIDAS images of GOES-15 0.63 µm visible channel data (above; click image to play animation) showed the hazy signature of a plume of re-suspended volcanic ash originating from the region of the Novarupta volcano in Alaska, moving southeastward over the Shelikof Strait toward Kodiak Island on 29 September 2014. The 1912 eruption of Novarupta left a very deep deposit of volcanic ash, which often gets lofted by strong winds in the early Autumn months before snowfall covers the ash (another example occurred on 22 September 2013). Surface winds gusted as high as 30 knots at regional reporting stations, with numerical models estimating terrain-enhanced winds as high as 40-50 knots over the Novarupta ash field.

An AWIPS II image of POES AVHRR 0.86 µm visible channel data (below) showed the ash plume at 22:46 UTC; a pilot report at 22:45 UTC indicated that the top of the ash plume was between 4000 and 6000 feet above ground level.

POES AVHRR 0.86 µm visible channel image, with METAR surface reports and Pilot reports (PIREPs)

POES AVHRR 0.86 µm visible channel image, with METAR surface reports and Pilot reports (PIREPs)

A sequence of 3 Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server (below) indicated that the re-suspended ash plume had been increasing in areal extent during that period.

Suomi NPP VIIRS true-color images from 27, 28, and 29 September

Suomi NPP VIIRS true-color images from 27, 28, and 29 September

A sequence of 4-panel products from the NOAA/CIMSS Volcanic Cloud Monitoring site (below) shows False-color images, Ash/dust cloud height, Ash/dust particle effective radius, and Ash/dust loading (derived from either Terra/Aqua MODIS or Suomi NPP VIIRS data).

4-panel MODIS/VIIRS products: False color image; Ash/dust cloud height; Ash/dust particle effective radius; Ash/dust loading

4-panel MODIS/VIIRS products: False color image; Ash/dust cloud height; Ash/dust particle effective radius; Ash/dust loading

Hat tip to Mark Ruminski (NOAA/NESDIS) for alerting us to this event.

Eruption of the Mount Ontake volcano in Japan

September 27th, 2014
Suomi NPP VIIRS true-color images on 27, 28, and 29 September

Suomi NPP VIIRS true-color images on 27, 28, and 29 September

The Mount Ontake volcano erupted on the main Japanese island of Honshu around 02:52 UTC (11:52 AM local time) on 27 September 2014. A sequence of three daily (27, 28, and 29 September) Suomi NPP VIIRS true-color Red/Green/Blue (RGB) images from the SSEC RealEarth web map server (above) showed the volcanic plume drifting eastward then southeastward during that period. The ash plume disrupted air travel in some parts of Japan.

A comparison of pre-eruption (22 September) and post-eruption (28 September) VIIRS true-color images (below) revealed the light gray signature of thick volcanic ash covering the region around the summit of Mount Ontake. There was also a narrow volcanic plume streaming southeastward on the 28 September image.

22 September vs 28 September VIIRS true-color images

22 September vs 28 September VIIRS true-color images

Eruption of the Sangeang Api volcano in Indonesia

May 30th, 2014
MTSAT-2 0.63 µm visible channel and 10.8 µm IR channel images at 08:32 UTC

MTSAT-2 0.63 µm visible channel and 10.8 µm IR channel images at 08:32 UTC

A comparison of McIDAS images of MTSAT-2 0.63 µm visible channel and 10.8 µm IR channel data at 08:32 UTC on 30 May 2014 (above) showed the volcanic cloud from the first in a series of eruptions of the Sangeang Api volcano in Indonesia (aircraft photos). The coldest cloud-top IR brightness temperature at that time was -74.5º C; note that the tall volcanic cloud was casting a large shadow toward the east-southeast in the visible image.

An animation of MTSAT-2 10.8 µm IR images (below; click image to play animation; also available as an MP4 movie file) revealed that there were a number of smaller eruptions that followed the initial, larger eruption.

MTSAT-2 10.8 µm IR channel images (click to play animation)

MTSAT-2 10.8 µm IR channel images (click to play animation)

 ———————————————————————————————————

MTSAT-2 false-color RGB images (click to play animation

MTSAT-2 false-color RGB images (click to play animation)

The NOAA/CIMSS Volcanic Cloud Monitoring MTSAT-2 false-color Red/Green/Blue (RGB) images (above; click image to play animation) showed the southeastward spread of volcanic ash cloud from the first 2 eruptions, while the Volcanic Ash Height product (below; click image to play animation) indicated that the ash may have reached altitudes of at least 12-14 km. Pilot reports in the vicinity placed the height of the volcanic cloud at 65,000 feet or 19.8 km.

NOAA/CIMSS Volcanic Ash Height product (click to play animation)

NOAA/CIMSS Volcanic Ash Height product (click to play animation)

Night-time McIDAS-V images of Suomi NPP VIIRS 11.45 µm IR, 3.9 µm shortwave IR, and 0.7 µm Day/Night Band (DNB) images of one of the secondary eruptions at 17:43 UTC on 30 May (below; courtesy of William Straka, SSEC) showed a cloud-top IR brightness temperature as cold as -77º C, along with the yellow-enhanced “hot spot” on the shortwave IR and the bright glow on the DNB image from the hot volcano vent and lava flows.

Suomi NPP VIIRS 11.45 µm IR, 3.9 µm shortwave IR, and 0.7 µm Day/Night Band images

Suomi NPP VIIRS 11.45 µm IR, 3.9 µm shortwave IR, and 0.7 µm Day/Night Band images

A composite of Suomi NPP VIIRS true-color RGB images from 31 May, viewed using the SSEC RealEarth web map server (below) showed the widespread extent of the volcanic ash cloud from the ongoing eruption.

Suomi NPP VIIRS true-color RGB image composite

Suomi NPP VIIRS true-color RGB image composite

Due to the southeastward drift of the primary volcanic ash plume toward Australia, flights were cancelled at the Darwin airport. MTSAT-2 visible and IR images with polygons of Volcanic Ash Advisories are shown below (click image to play animation).

MTSAT-2 visible and IR images, with Volcanic Ash Advisory polygons

MTSAT-2 visible and IR images, with Volcanic Ash Advisory polygons

===== 01 June Update =====

A comparison of Suomi NPP VIIRS true-color images from 31 May and 01 June (below) showed that while the eruption was still ongoing, the amount of ash output had dramatically decreased.

Suomi NPP VIIRS true-color images

Suomi NPP VIIRS true-color images