New study to help inform climate models
By Summit Voice
SUMMIT COUNTY — Using data from sensitive satellite instruments, researchers at the University of Saskatchewan have determined relatively small volcanic eruptions can affect climate on a global level, as aerosols from the eruptions are transported into the upper levels of the atmosphere by weather systems like monsoons.
“If an aerosol is in the lower atmosphere, it’s affected by the weather and it precipitates back down right away,” said Adam Bourass, with university of Saskatchewan’s Institute of Space and Atmospheric Studies. “Once it reaches the stratosphere, it can persist for years, and with that kind of a sustained lifetime, it can really have a lasting effect,” Bourass said, explaining that the particles scatter incoming sunlight, thus cooling the Earth’s surface.
Bourassa said that, until recently, researchers believed that only large eruptions could inject aerosols into the stratosphere, beyond the turbulent troposphere.
For example, the massive eruption of Mount Pinatubo in the Philippines in 1991 temporarily dropped temperatures by half a degree Celsius world-wide.
The calm layers of the stratosphere are at least 10,000 meters high — higher near the equator — and perturbations in the lower atmosphere have a hard time piercing through the boundary. For example, the distinctive flattened “anvil” shape at the top of large thunderstorms is created as the storm pushes against the stratosphere.
But data gathered by the Canadian Space Agency’s OSIRIS instrument aboard the Swedish satellite Odin detected volcanic gas and lighter liquid droplets from the 2011 Nabro eruption penetrating the stratosphere, leading to the largest stratospheric aerosol load recorded by OSIRIS in its more than 10 years of flight.
Regional winds carried the volcanic gas and aerosol – minute droplets of sulfuric acid – into the path of the annual Asian summer monsoon, where it they were able to mix into the stratosphere.
“There are only a few instruments that can measure stratospheric aerosols, and OSIRIS is one of them,” Bourassa said. “It’s become extremely important for climate studies, because we’ve captured more than a full decade of data. The longer it’s up, the more valuable it becomes.”
The hope is these latest findings will provide another piece of the puzzle to allow more accurate models of climate behavior and change.
The research team includes scientists from the U of S, Rutgers University in New Jersey, the National Centre for Atmospheric Research in Colorado, and the University of Wyoming.
The research appeared in the July 6 issue of the journal Science.