The Tungurahua Volcano in Ecuador began to have a series of eruptions during the first 2 weeks of February 2008 (Washington VAAC advisories). A comparison of 4 different GOES-10 Imager and Sounder products (above) shows the Imager 10.5µm “IR window”, the Imager 10.5-12.0µm “split window difference”, the Sounder 11.0-12.0µm “split window difference”, and the Sounder 7.4-13.3µm “SO2 detection product”. A volcanic ash plume was evident on both the Imager and Sounder split window difference products, moving southwestward away from the volcano at 16:31-16:45 UTC on 06 February 2008. The lack of a signal on the SO2 detection product could have been due to masking by clouds, or the fact that very little SO2 was present in that particular volcanic ash plume.
A comparison of GOES-10 split window difference and IR window images from 06:15-13:15 UTC on 06 February (above) show the improved volcanic ash detection capability of the 11-12µm technique — ash shows up as red features in the split window difference product.
An animation of the GOES-10 visible channel imagery from 06 February 2008 (above) shows the plume of volcanic ash drifting southwestward.
An animation of GOES-10 IR “split window difference” (10.5µm – 12.0µm, top panel) and IR window (10.5µm, bottom panel) imagery from (above) showed two separate pulses of volcanic ash cloud (gray enhancement) that were drifting southwestward on that day. Two days later, on 08 February (below), a new ash cloud was seen to be drifting almost due west.
Then on 10 February (below), two separate ash clouds could be seen — one drifting eastward, and one drifting westward — as changes in wind direction with height (wind shear) moved the volcanic ash plumes in different directions.