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Last Updated: Friday, 9 December 2005, 07:22 GMT
Europe's pollution hotspots shown
By Jonathan Amos
BBC News science reporter, San Francisco

The maps can pinpoint the sources of pollutants (Image: KNMI/FMI/NIVR/Nasa)

Dutch scientists are putting together remarkable maps showing pollution over Europe and other regions of the globe.

Using the US space agency's Aura satellite, the team can look right down to the troposphere, the lowest part of the atmosphere where we all live.

The Ozone Monitoring Instrument (Omi) and other key equipment on Aura can build a daily picture of air quality.

The pollution maps, which can see detail at the city scale, will be used to identify problem hotspots.

"This is the first time that we have been able to follow pollution globally from day to day," said Pieternel Levelt, of the Royal Netherlands Meteorological Institute, who is Omi's principal investigator.

"This will help us understand how pollution is formed and where it comes from, its sources; and where it goes to, its sinks.

"All this helps us understand the chemistry involved and that is important for us if we want to check our models."

Long track

Dr Levelt was speaking at the American Geophysical Union (AGU) Fall Meeting.

Her team was presenting maps it is developing to track nitrogen dioxide (NO2).

The gas - which comes from motor vehicle exhausts, power plants and industry - is an important precursor in the production of ground-level ozone, part of the photochemical smog that can blight city air, particularly in summer.

Aura (Nasa)
Aura keeps a watch over the Earth's atmosphere
By following the development and spread of NO2, Omi can be used to help make forecasts of where problem air might develop. Long-term tracking of the gas can also identify emission hotspots.

One map presented at the AGU, pulling together data gathered from May to September this year, showed expected high emissions over some of Europe's cities, and in particular over Antwerp, Rotterdam and the Ruhr.

Omi, which is a Dutch-Finnish instrument, can also detect formaldehyde, sulphur dioxide, small particles, as well as tropospheric ozone.

The Dutch are in the pilot stage of their mapping project but expect eventually to start providing invaluable data for all parts of the world.

Ice uncertainty

Omi is just one of four instruments on Aura that is giving researchers an extraordinary picture of the lower atmosphere.

The AGU meeting was told the spacecraft's Microwave Limb Sounder (MLS) instrument had recently begun offering the first observations of ice in clouds on a global basis.

This information is critical to our understanding of climate change.

Clouds are one of the big uncertainties in atmospheric modelling. Some types of cloud will reflect solar radiation and help cool the planet, others will trap radiation and warm the Earth's surface.

"There is a very wide disagreement in the models about how to represent cloud ice and that limits our confidence in the climate change predictions they provide," said Duane Waliser, a principal scientist at the US space agency's Jet Propulsion Laboratory.

"It's very important this is rectified."

'Eye in the sky' watches over air
20 Dec 04 |  Science/Nature
Nasa launches its Aura satellite
15 Jul 04 |  Science/Nature

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