Volcano's fury gives NOAA a chance to try out new computer models
Lack of data on ash plumes makes forecasting difficult, but the agency is testing models that could help
- By William Jackson
- Apr 20, 2010
The eruption of a volcano on Iceland that has shut down commercial air traffic in much of Europe since late last week is giving the National Oceanic and Atmospheric Administration a chance to try out an advanced computer model for predicting volcanic ash dispersion.
The current state of the art and science of volcanic ash is limited by a lack of detailed information about the composition of the clouds of ash spewed by erupting volcanoes, which can threaten aircraft and change the Earth’s weather, said Gary Hufford, a physical scientist with NOAA’s National Weather Service.
“We can advance the science so we can do a better job of detecting the ash,” Hufford said Tuesday during a NOAA briefing on the eruption of the Eyjafjallajokull volcano.
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The agency plans this week to begin testing a version of a computer simulation that includes chemistry data in an effort to produce more accurate results, he said.
Tracking and predicting the movement of clouds of volcanic ash is important because of their potential effect on aircraft and weather. The threat of damage to aircraft has disrupted European and transatlantic air travel this week, even though little still is known about the threat.
“Bad things can happen if planes fly into ash clouds,” said Tony Hall, director of NOAA’s Alaska Volcanic Ash Advisory Center and Aviation Weather Center in Anchorage. That is why two NOAA advisory centers and seven others around the globe monitor and issue warnings and advisories about the clouds.
But there is not enough data from the airline and aircraft industries to fully understand the threat to planes. In 1998 a NASA research plan suffered $3 million in damage when it flew into a cloud of ash too light to be detected. So the U.S. airline industry has a zero-tolerance policy for ash risk, and since 1980 only about 100 planes around the world have suffered ash damage.
Another weak spot in understanding the threat is a lack of data about the clouds themselves. Because planes do not fly into them, little is known of the particle size, concentrations and chemical makeup of the plumes. Another missing element is how high the ash travels, because observations from weather satellites do not give good data on altitude.
One bright spot in ash cloud research is the possibility that samples could be gathered by unmanned planes, Hufford said.
Existing computer models are helpful in predicting where the plumes will go. One being used to track the Eyjafjallajokull plume over northern Europe is called HYSPLIT — the Hybrid Single Particle Lagrangian Integrated Trajectory Model — developed by NOAA’s Air Resources Laboratory and used by the weather service.
However, “in real time we don’t know the amount of ash being emitted into the atmosphere, and concentrations can’t be determined downwind,” said Barbara Stunder, research meteorologist in NOAA's Air Resources Laboratory.
A model that offers more detail is the Flow Following Finite-Volume Icosahedral Model, or FIM, being developed by NOAA Research. FIM is not brand new, but the chemistry elements executed within it have only been tested in the last few days, said Stan Benjamin, director of the forecast branch of the research division’s Global Systems Division. It is expected to get trial runs on the Eyjafjallajokull plume this week and to soon join other production computer models used by NOAA.
Although meteorologists in the United Kingdom recently issued an advisory for eastern Canada for some low-level ash drifting westward from Iceland, the clouds are not expected to hit U.S. airspace, Hall said. “We are watching it closely, though.”
The climate impact of the eruption also is expected to be negligible, although ash in the jet stream could bring some nice sunsets to the U.S. West Coast by the end of the week.
William Jackson is a Maryland-based freelance writer.