ANALYSIS: WEATHER FORECASTING: Weather Satellite Heralds Return of `the Wow Factor' - and It Could Alter Our Lives in Forecasting ; the Latest in Satellite Technology Has Just Been Blasted into Space, and It Will Force Meteorological Scientists to Rewrite Their Programs

Article excerpt

THREE YEARS after Sputnik, the Soviet satellite that was the first to orbit Earth, went up in 1957, the Americans sent up their own satellite, Tiros 1, to take pictures of the planet. "The effect on people was - wow," said Martin Jones, head of the space programme at the UK Meteorological Office in Hadley. Weather forecasters, seeing the patterns of clouds swirling around the globe, realised that satellite pictures would revolutionise their lives, and everyone else's too.

It also meant that they had to tear up their computer programs, said Martin Shelley, head of science at the British National Science Centre. "Until then, they had just estimated how much cloud cover there was over the oceans, which makes a big difference to the weather on the land. When they saw the pictures, they had to redo all their algorithms."

On Wednesday night the latest in weather satellite technology was blasted into space from French Guyana, the first of three Meteosat Second Generation (MSG-1) satellites that will become operational over the next 12 years, in a pan-European project costing about pounds 800m, of which Britain is contributing pounds 95m.

MSG-1 would alter our lives too, said Dr Tillman Mohr, director general of Eumetsat, which co-ordinates meteorological satellites for 18 European countries. "This programme is the culmination of more than 10 years' work by literally hundreds of people, all acting as a team, throughout Europe."

Just like its American forebear, MSG-1 could lead to a mass scrapping of weather programs, Mr Shelley said. On board is a scientific system called GERB - Geostationary Earth Radiation Budget - which will measure how much energy the earth and the oceans receive, and how much they radiate back into space. "At present nobody knows quite how much energy is used up. It's a big debate in global warming, understanding the energy balance," he said

That, for now, remains in the future. But weather satellites have a glowing past. The first generation of Meteosat satellites began going aloft in 1977; there are seven still locked in geostationary orbit around the equator, so that they appear to remain in the same place relative to the surface.

Compared with those ageing systems, MSG will be able to send back pictures twice as often - every 15 minutes, rather than 30 - and measure reflected radiation at 12 wavelengths rather than the three that its predecessor, the first generation of Meteosat satellites, was able to do. "It will have better resolution in its pictures," said Mr Jones at the Met Office. "The combination means that we will be able to detect and measure the presence of fog - which has a very different reflection `signature' from clouds - and low cloud, snow, and even volcanic ash."

The way we understand what is happening above us has changed drastically in the past few years. Partly that is because satellites bring better pictures; but largely it is because we have more powerful computers to marry the data collected at ground level by a network of stations, to that collected by weather balloons - which still play an important part - with the newest satellite data.

Mr Jones said: "We reckon that if all the satellites were knocked out today by something, then the quality of our forecasting would fall by 10 to 15 per cent. We reckon our accuracy is in, well, say the low 90 per cents." The comparison is made by looking at what was predicted with what weather arrives. "To put it another way, the three-day forecast now is as good - that is, as reliable, as accurate - as the one-day forecast was seven to 10 years ago. …