A global map of nitrogen dioxide in the atmosphere has revealed the most precise view yet of pollution hotspots around the world.
The map, based on 18 months' worth of satellite data, shows very high levels of NO2 above major European and North American cities and across much of north-east China. South-east Asia and Africa also have raised concentrations of the gas due to their burning of vegetation.
But perhaps more surprising are the oceans. "Ship tracks are visible in some locations," says Steffen Beirle, one of the research team at the University of Heidelberg, Germany. "Look at the Red Sea and the Indian Ocean between the southern tip of India and Indonesia."
Although NO2 is formed naturally by lightning and by microbes in the ground, it is also released into the atmosphere from the burning of fossil fuels by power plants, heavy industry and vehicles. Large quantities of the gas can cause respiratory problems and lung damage, and can also contribute to harmful ozone forming near ground level.
"Our results could be used for air quality prediction in future," says Beirle. "But for now we are focused on quantifying the contributions of the different sources of nitrogen oxides." The amount produced by lightning is still highly uncertain, he notes.
Data for the map were obtained between January 2003 and June 2004 from the European Space Agency's Envisat satellite, which scans the globe every six days.
The instrument used was the Scanning Imaging Absorption Spectrometer for Atmospheric Chartography (SCIAMACHY), developed by John Burrows at the University of Bremen, Germany.
"The satellite measures light reflected by the Earth," says Beirle. "Different gases in the atmosphere have a characteristic absorption." The absorption patterns produced by the major gases present in the atmosphere - such as oxygen, nitrogen and water - are factored out to reveal the level of pollutants such as NO2.
An earlier satellite, called the Global Ozone Monitoring Experiment, also produced an image of global pollution but at a much lower resolution. "The higher spatial resolution delivered by SCIAMACHY means we see a lot of detail, even resolving individual city sources," says Beirle.
He adds that SCIAMACHY is also a great improvement for the imaging of other trace gases, such as carbon dioxide and methane.
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Thu Mar 04 13:40:12 GMT 2010 by Charlotte Green
I think Birmingham UK is like a mini New York or Moscow. Cold and pulluted. Please do soomething about Birmingham in the UK!!!!
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