NOAA-NESDIS
Regional And Mesoscale Meteorology Team
Daily Satellite Discussion
Tuesday October 28,1997
Figure 1
GOES-8 Visible Imagery
click to enlarge
Figure 2
GOES-8 Multichannel Imagery
click to enlarge
Figure 3
Nighttime GOES-8 Multichannel Imagery
click to enlarge
The Soufriere Hills Volcano on Montserrat had another violent erruption on 21 October 1997. The ash plume poses a serious aviation hazard, and the extent of the plume can be monitored with satellite imagery. During daylight hours, the plume can readily be tracked with the GOES-8 15 minute high resolution Visible imagery. Figure 1 shows 15 minute imagery from 1531 UTC until 2045 UTC, after which it begins to get dark over the region.

The ash plume can also be tracked with multichannel imagery. Figure 2 presents an 1845 UTC comparison of the Visible imagery, the 3.9/10.7 micrometer reflectivity product, the 10.7/12.0 micrometer difference product and a new experimental product combining the reflectivity and 10.7/12.0 micrometer difference product. Unlike the Visible imagery, multichannel imagery allows for continuous tracking of the ash plume after dark. Figure 3 is an example of the detection of the plume after dark at 2215 UTC using the reflectivity product, the 10.7/12.0 micrometer difference product and the new 3.9/10.7/12.0 micrometer product. Note that while the blue region in the test product highlights the thickest portion of the plume and draws our eye to that region, examining imagery before this time from the various channels helps us determine the full extent of the plume.

See the August 12 discussion for reference to other Volcanic Ash detection using satellite imagery.

Bernadette Connell

We welcome your comments and discussion at ramsdis@comet.ucar.edu

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