The detection and monitoring of volcanic ash clouds is particularly important for aviation safety since volcanic particulates can cause serious damage to aircraft engines. The volcanic ash cloud in this example is from an eruption on Mt. Ruapehu, in New Zealand, on June 17th of 1996. This ash cloud and subsequent eruptions caused the Wellington airport to cease operations for several days.
Three products from GOES are useful in monitoring the evolution of volcanic ash clouds. They are daytime VIS
imagery (seen in the upper left at 0300 UTC) during daylight hours; the 3.9 um reflectivity product (upper right); and a
new ash cloud product (lower right), a scaled temperature difference between the 10.7 and the 12.0 micrometer
channels, made useful because of the absorption by sulphur dioxide in the 12 um band. Notice how well the volcanic
ash plume can be seen in all three images at 0300 UTC. At night, 10.7 micrometer
imagery (replacing the VIS imagery in the upper left at 0900 and 1200 UTC in this example) does not reveal the ash
cloud, however it is detectable in both the reflectivity and the ash cloud products at 0900 UTC and, three hours later, at 1200 UTC.
Note how the volcano's hot lava region is detectable in the reflectivity product, since it is not obscured by ash cloud.
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