BoM-Darwin Volcanic Ash Advisory Centre

Darwin Volcanic Ash Advisory Centre graphic

Rinjani, Lombok, Indonesia, September 1994

(Related pages: Rinjani, July 1994, Rinjani, August 1994)

NOAA, 5 September
Image source: NOAA-12, 5 September 1994 2330 UTC, enhanced infrared & visible.

Comments: These fascinating images show what almost appear to be 'smoke rings' being blown off by the volcano. The ash cloud is thickest to the south, suggesting this is the youngest of the plumes, but the two plumes to the northeast suggest either a wind change during the night, or else a wind profile that is causing the ash to circle around as it ascends.

NOAA, 10 September
Source: NOAA-12, 10 September 1994, visible.

Comments: Again, a twisted plume shape, suggesting a steady ascent of the plume through varying wind fields. The very clear shadow to the west of the upper portions of the plume (this image was taken early in the day) shows, by its distance from the plume, that the plume is much higher at its southeastern extent. Images like this can be used to estimate the plume high through simple trigonometry.

Multiple Channel image
Source: As above, multiple channel.

IR animation, 10-11 September
Source: GMS infrared, 10-11 September 1994

Comments: The animations above and below, for the same 'twisted plume' event, show how quickly the ash clouds evolve and dissipate. Thus, while the NOAA polar orbiting satellites provide a detailed 'snapshot' of the event, the geostationary satellites such as GMS give a much better temporal view.

Visible animation
Source: as above, visible.

NOAA image, 11 September
Source: NOAA-11, 11 September 1994, enhanced.

Comments: This image shows how effective the processing algorithm can be at picking discrete ash clouds that have travelled some distance from the volcano.

(Related pages: Rinjani, July 1994, Rinjani, August 1994)

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