Ozone helps to shield the Earths surface from the harmful ultraviolet (UV) light rays of the Sun. For example, if an ozone hole opens above Europe in the summer, then the risk of sunburn and skin cancer in the longer term increases dramatically for sun worshippers at the beach.

The speed of the new service makes it possible to broadcast warnings far more quickly, and to make more accurate forecasts of potential danger. However, the real sophistication and benefit of this new service is its ability to plot a profile of ozone density at various altitudes, rather than simply calculating the amount of ozone in a tower of air reaching from ground to space.

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"The main reason for making this service available is to enable the creation of improved weather forecasts," said Ronald van der A, a senior project scientist at KNMI. "Ozone moves with the wind in the high atmosphere we call it a stratospheric tracer. Because we can generate these three-dimensional profiles quickly, we can create moving maps from a series of snapshots. And [thus we can]start to model the behavior of the stratosphere much more accurately."

"Three years ago, most people thought that this could not be feasible," said the ESAs Claus Zehner. Zehner extended the European Remote Sensing satellite (ERS) ground segment to speedily provide Global Ozone Monitoring Experiment (GOME) measurements to KNMI for the development of this new service to users.

GOME is the Global Ozone Monitoring Experiment aboard the European Remote Sensing satellite, ERS-2, launched in 1995. It continues to contribute to environmental monitoring and to the understanding of the physical and chemical processes underlying Earth systems, both on a global and local scale.

...because we can see events developing quickly, if we spot a hole appearing, we can alert local scientists who can then monitor the event hour by hour.

"The big challenge is the computation," said van der A. "To calculate total ozone, youre using only part of the spectrum of light scattered back by the Earths atmosphere. But to generate the profile, you look at a much wider spectrum, each segment of which corresponds to a backscattering layer at a particular altitude in the atmosphere. Again, in itself this is not such a big task -- the real breakthrough is to be able to extract this profile information from the data in near real-time. We can publish the profiles with three hours of the data being gathered," he said.

With the fast-delivery service, data are acquired and processed to total ozone columns on global maps within three hours after acquisition. Then these data are used in a model to forecast the ozone, and an algorithm is applied to give the UV index, allowing accurate forecasting within 24 hours.

Although it still takes three days to completely cover Earth's surface, the near-real-time processing allows a complete global picture to be available in the same time frame, which is a major advance over any previous efforts.

"Equally," said van der A, "because we can see events developing quickly, if we spot a hole appearing, we can alert local scientists who can then monitor the event hour by hour, using equipment carried aboard specially launched balloons, called sondes."

The service is now live, providing GOME ozone profiles to scientists around Europe, as well as UV index forecasts.

"And we will certainly continue the service when Envisat is launched," said van der A. "The SCIAMACHY (SCanning Imaging Absorption Spectrometer for Atmospheric CartograpHY) instrument aboard Envisat may well allow us to improve the quality still further."