17 April, 2013

Jet stream influences extreme storms

A new study of Europe’s extreme storm events reveals that they often occur near  the jet stream – the fast flowing air currents that flow high in the Earth’s atmosphere.

The study further reveals that storms also bunch together in time – with extreme events sometimes happening closer to each other than traditional weather predictions would suggest. This bunching can then have a knock-on effect of leaving a larger gap than predicted between those events and the following storm cluster.

In a paper published this week in a special issue of Philosophical Transactions of the Royal Society A, Dr Christian Franzke, of British Antarctic Survey, examines the impact of the North Atlantic jet stream on extreme wind speeds and storms in Europe.

The impact of natural hazards that can cause significant damage in economic and human terms is of great interest to Government, business and society.  European wind storms rank as one of the major causes of global natural catastrophe insurance losses.

The scientific community strives to improve models and predictions.  This requires a deep understanding of the pattern and frequency of extreme storm events.

Dr Franzke’s analysis of weather station and satellite data for the North Atlantic and European region between 1958 to 2001 leads him to conclude that the jet stream exerts an influence on wind speeds and that the clustering of storms in time is not just down to coincidence.  He says,

“The point was to see if the bunching together of extreme storms is more than just due to chance like a roll of the dice – to see if there is a systematic process leading to clustering. I wanted to find out what might be considered to be the ‘normal’ pattern and see if there was a connection between storms and the jet stream. The data show that storm clusters often follow the track of the jet stream. This is a new step forward in our understanding of this complex and complicated process. This research will help forecasting future storm events and is particularly important because we expect to see an increase in the intensity of storms due to climate change”.

ENDS

Issued by the British Antarctic Survey Press Office.

Contact:

Paul B. Holland, Tel: +44 (0)1223 221226; Mob: + 44 07740822229; email: pbmho@bas.ac.uk

Dr Christian Franzke, Tel: 01223 221350; email: chan1@bas.ac.uk

Notes for editors

Dr Franzke’s paper Persistent Regimes and Extreme Events of the North Atlantic Atmospheric  Circulation is published in Philosophical Transactions of the Royal Society A, Mathematics applied to the climate system. 15 April 2013

For further information on the Royal Society please visit http://royalsociety.org or contact assistant press officer Natasha Little – Tel: +44 20 7451 2510.

The jet stream is a major motor for climate in Europe and moves slightly north and south as the seasons change. In recent years its movement has, on average, been more towards the North Pole and occurs about 10-15km altitude.

The Royal Society is a self-governing Fellowship of many of the world’s most distinguished scientists drawn from all areas of science, engineering, and medicine. The Society’s fundamental purpose, as it has been since its foundation in 1660, is to recognise, promote, and support excellence in science and to encourage the development and use of science for the benefit of humanity.