The plume of sulfur dioxide from the eruption of the Kasatochi Volcano in the first week of August continued its trans-continental trek across North America on August 13, 2008. This image based on data from the Ozone Monitoring Instrument on NASA’s Aura satellite shows sulfur dioxide concentrations high in the atmosphere (higher than urban and industrial pollution would be found). The volcanic gas spread across the Arctic and also dipped southward across Canada and into the Northeast United States.
The scale shows values as the natural logarithm of Dobson Units of sulfur dioxide. A logarithmic scale is one in which the values represented by the colors increase exponentially, not linearly. A Dobson Unit is a measure of the concentration of the gas in a 15-kilometer tall column of the atmosphere. If you could compress all the sulfur dioxide in that column of the atmosphere into a flat layer at the Earth’s surface (at 0 degrees Celsius), one Dobson Unit of the gas would be 0.01 millimeters thick, and it would contain 0.0285 grams of sulfur dioxide per square meter.
Additional images showing the spread of the sulfur dioxide plume from this eruption are featured in an Image of the Day.
NASA OMI image courtesy Simon Carn, Joint Center for Earth Systems Technology (JCET), University of Maryland Baltimore County (UMBC). Caption by Rebecca Lindsey.
After earthquakes and other seismic activity starting on August 7, 2008, Kasatochi Volcano began erupting large plumes of ash and gases in subsequent days. Over the following week, the plume of sulfur dioxide spread across Canada and the Northeast United States.