Explaining Timescales Associated with Jet Stream Variability

Funder

NERC SCENARIO

Project Team

Prof. John Methven, Dr Tom Frame, Dr Paul Berrisford

Partners

ECMWF

Timescales

2016-2019

Country/Region

UK

Key Contact

Sandra Hansen

Keywords

jet stream, dynamics, Rossby waves, persistence, variability, modes, wave activity

Status

Current

Background

Extreme weather on a monthly or seasonal timescale is associated with persistent large-scale weather patterns.

For example, the unusually wet summers of 2007, 2008 and 2012 in the UK were associated with a similar Rossby wave pattern on the jet stream which was almost stationary over the UK.

A contrasting season was winter 2013/14 where the jet stream was directed at the UK and extreme seasonal rainfall resulted from a succession of weather systems hitting the UK.

In both examples, the persistence in the latitude of the jet stream is a key player.

This project aims to gain a theoretical understanding of the persistence of the jet stream, by looking at Rossby wave structures.

This could improve future prediction of extreme weather events.