Mt. Etna, a volcano on the island of Sicily, erupted on October 26, 2002.
Preliminary analysis of data taken by the Atmospheric Infrared Sounder
(AIRS) on NASA's Aqua satellite on October 28 shows the instrument can
provide an excellent means to study the evolution and structure of the
sulfur dioxide plume emitted from volcanoes. These data also demonstrate
that AIRS can be used to obtain the total mass of sulfur dioxide injected
into the atmosphere during a volcanic event, information that may help us
to better understand these dangerous natural occurrences in the future.
The image clearly shows the sulfur dioxide plume. This image was created
by comparing data taken at two different frequencies, or channels, and
creating one image that highlights the differences between these two
channels. Both channels are sensitive to water vapor, but one of the
channels is also sensitive to sulfur dioxide. By subtracting out the
common water vapor signal in both channels, the sulfur dioxide feature
remains and shows up as an enhancement in the difference image.
The Atmospheric Infrared Sounder Experiment, with its visible, infrared,
and microwave detectors, provides a three-dimensional look at Earth's
weather. Working in tandem, the three instruments can make simultaneous
observations all the way down to the Earth's surface, even in the presence
of heavy clouds. With more than 2,000 channels sensing different regions
of the atmosphere, the system creates a global, 3-D map of atmospheric
temperature and humidity and provides information on clouds, greenhouse
gases, and many other atmospheric phenomena. The AIRS Infrared Sounder
Experiment flies onboard NASA's Aqua spacecraft and is managed by NASA's
Jet Propulsion Laboratory, Pasadena, Calif., under contract to NASA. JPL
is a division of the California Institute of Technology in Pasadena.