Plane turbulence: Storms present new front

THUNDERSTRUCK: Thunderstorms play a more critical role in turbulence than previously thought.
THUNDERSTRUCK: Thunderstorms play a more critical role in turbulence than previously thought.

Australian researchers have discovered storms can cause turbulence more than 100km away - a revelation which they say should prompt a complete re-write of aircraft safety guidelines.

New research out of the Melbourne University's Centre of Excellence has shown thunderstorms could produce unexpected atmospheric gravity waves more than 100km away from storm cells.

Chief investigator Todd Lane said air safety guidelines worldwide did not take them into account.

"It is likely that many reports of encounters with turbulence are caused by thunderstorm generated gravity waves, making them far more important for turbulence than had previously been recognised," he said.

"Previously it was thought turbulence outside of clouds was mostly caused by jet streams and changes in wind speed at differing altitudes, known as wind shear, but this research reveals thunderstorms play a more critical role."

The research, published in the Bulletin of the American Meteorological Society, showed thunderstorms could have far more reaching effects.

Lane said it was now recognised that thunderstorms significantly modified the airflow, strengthening the jet stream and enhancing wind shear at a significant distance from the storm cell itself.

Many flights, including those operating in New Zealand, detoured around storm cells.

However, Lane said the research indicated they could still be close enough to encounter gravity waves and clear-air turbulence.

The researchers said the unexpected turbulence could lead to passenger injuries.

It is estimated about 97 per cent of injuries caused by turbulence during flight occurred because people were not wearing seatbelts. On average, around 15 people are injured every year due to turbulence.

Beyond the immediate safety concerns, it has been estimated that turbulence costs the aviation industry more than $100m a year globally due to associated rerouting and service checks, Lane said.

Despite this, he said little research was being carried out even though advances in technology now made it possible.

"Ten years ago, we didn't have the computing power and atmospheric models to answer some of the important questions around turbulence.

"Now we can answer some crucial questions but there are only a few groups working on this problem. We need more researchers to become engaged to improve the guidelines and passenger safety," Lane said.