Ulawun volcano erupts in Papau New Guinea

June 26th, 2019 |

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

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

The Ulawun volcano erupted just after 0430 UTC on 26 June 2019 — a comparison of Himawari-8 Visible (0.64 µm), Shortwave Infrared (3.9 µm) and Infrared Window (10.4 µm) images (above) showed the thermal anomaly (yellow to red 3.9 µm pixels) preceding the eruption and the development of a well-defined umbrella cloud after the eruption. The coldest cloud-top infrared brightness temperature was -83.6ºC in conjunction with a prominent overshooting top at 0600 UTC. Note the eastward-moving cloud material that originated from this overshooting top — judging from Merauke/Mopah, Indonesia rawinsonde data (plot | data), the westerly winds required for such transport existed in the stratosphere at altitudes of 20-24 km. The pocket of warmer cloud-top 10.4 µm brightness temperatures associated with this stratospheric cloud material was the warmest at (-57.2ºC) at 0640 UTC (which, with the adjacent -82.7ºC overshooting top, created a cold/warm couplet whose magnitude was 25.5ºC). In addition, concentric gravity waves propagating outward across the volcanic cloud top were evident on the imagery.

Himawari-8 Infrared Window images (below) showed that the volcanic cloud dissipated fairly quickly. The eastward drift of the stratospheric cloud material also became difficult to follow after a couple of hours — even in Low-level Water Vapor (7.3 µm) imagery (which is also sensitive to SO2 absorption).

Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 Infrared Window (10.4 µm) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images (below) revealed a thermal anomaly or “hot spot” (yellow to red pixels) for several hours leading up to the 0430 UTC volcanic eruption.

Himawari-8 Shortwave Infrared (3.9 um) images [click to play animation | MP4]

Himawari-8 Shortwave Infrared (3.9 µm) images [click to play animation | MP4]

Regarding the intensity of the thermal anomaly, a plot of volcano radiative power (VRP) and volcanic cloud longwave infrared brightness temperature (below) showed that the VRP exceeded 1 GW several hours prior to the formation of the eruption umbrella cloud.

Plot of volcano radiative power (red) and volcanic cloud longwave infrared brightness temperature (green), courtesy of Mike Pavolonis (NOAA/NESDIS) [click to enlarge]

Time series plot of volcano radiative power (red) and volcanic cloud longwave infrared brightness temperature (green), courtesy of Mike Pavolonis (NOAA/NESDIS) [click to enlarge]

Himawari-8 False Color RGB imagery along with radiometrically retrieved Ash Height, Ash Effective Radius and Ash Loading products (below) revealed a volcanic cloud characterized by high ash loading of large particles, having height values generally in the 16-20 km range (with a maximum height of 22 km).

False Color RGB (top left), Ash Height (top right), Ash Effective Radius (bottom left) and Ash Loading (bottom right) [click to play animation | MP4]

False Color RGB (top left), Ash Height (top right), Ash Effective Radius (bottom left) and Ash Loading (bottom right), courtesy of Mike Pavolonis (NOAA/NESDIS) [click to play animation | MP4]

An oblique view of of the Ulawun volcanic cloud was provided by GOES-17 “Red” Visible (0.64 µm) images (below). This view accentuated the vertical extent of overshooting tops, and the large solar angle helped to highlight the cloud-top gravity waves. The 3-dimensional aspect of the two distinct eruption pulses (with umbrella clouds at two different altitudes) along with the westward-drifting stratospheric plume were a bit more obvious in the GOES-17 images.

GOES-17 "Red" Visible <em>(0.64 µm)</em> images [click to play animation | MP4]

GOES-17 “Red” Visible (0.64 µm) images [click to play animation | MP4]

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