Scientists Explain Wayward Weather Forecasts

By Stuart Coles, PA News, 17 March 2004

Scientists at Oxford University say they have discovered what could be behind some wayward weather forecasts.

The researchers say small atmospheric fluctuations ignored by meteorologists may have a far greater impact on weather systems than previously thought.

The fluctuations, known as inertia-gravity waves, can often be seen from the surface of the Earth as stripy features in clouds, but forecasters had always thought they had little effect on cold and warm weather fronts.

The waves can be found in the bottom 15 kilometres (9.3 miles) of the atmosphere but wavelengths can be as short as 5 kilometres long (3.1 miles) - too small to be picked up by current weather prediction models, which divide the surface of the Earth into grid-boxes measuring around 50km (31.25 miles) by 50km.

Atmospheric physicists Dr Paul Williams and Professor Peter Read developed a computer model to mimic the behaviour of the atmosphere and say the waves could be leading to "significant errors" in some forecasts.

Dr Williams said: "More research is needed to find out exactly how bad the forecast error might be, but the preliminary results are very exciting.

"People in the past have thought they were too small to have any real effect. It sounds bizarre to suggest that adding random noise to a forecast might help to improve it, but science is always full of surprises."

Their research, published in Nonlinear Processes in Geophysics, is to be taken further by The European Centre for Medium-Range Weather Forecasts in Reading, a research centre with 25 countries involved.

But Dr Williams said it could be some time before others such as the Met Office took the idea on.

"Hopefully, it will feed into forecasts in a few years, but it is a bit delicate as it's an admission that something is not quite right now."