Himawari-9 Infrared Window (10.4 µm) images from 1110-1600 UTC on 17 April [click to play animated GIF | MP4]

10-minute JMA Himawari-9 AHI Infrared Window (10.4 µm) images (above) showed an explosive eruption of Mount Ruang in Indonesia on 17 April 2024. Note that a thunderstorm was reported at Menado (station identifier WAMM) from 1400-1430 UTC, due to abundant lightning activity within the dense volcanic umbrella cloud.

Himawari-9 Infrared Window (10.4 µm) image at 1240 UTC on 17 April [click to enlarge]

In the Himawari-9 Infrared Window (10.4 µm) image at 1240 UTC (above), the coldest pixel exhibited a brightness temperature of -88.8ºC (dark purple enhancement) — with an adjacent warm pixel of -46.4ºC (green enhancement), possibly a result of compensating subsidence immediately downwind of the robust updraft (which penetrated the local tropopause and extended into the lower stratosphere).

Maximum radiometrically retrieved Ash Height values (source) reached 16-18 km. In a plot of rawinsonde data from Menado at 1200 UTC (below), this height corresponded to the 80-110 hPa pressure level.

Plot of rawinsonde data from Menado at 1200 UTC on 17 April [click to enlarge]

In Himawari-9 Ash RGB images created using Geo2Grid (below), shades of pink around the the umbrella cloud represented higher concentrations of volcanic ash, while shades of green to yellow represented increasing concentrations of volcanic SO2.

Himawari-9 Ash RGB images, from 1110-1600 UTC on 17 April [click to play animated GIF | MP4]

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