BBC weatherman Nick Miller looks at the science behind what happened to Britain’s wild weather in 2012.
Britain went fro the worst drought in a generation to record-setting rains – the wettest year on record. And it may have been caused by a similar event seen in North America – the placement of the jet stream.
We just witnessed a winter storm in the USA driven by the jet stream. It snowed in Little Rock. There were ice storms across the country.
The position of the jet stream can vary by quite a bit. In early December, two large highs – in the North Pacific and on in the North Atlantic, pushed the jet streams farther north, bringing warm temperatures. The Atlantic one is a cyclical one called the North Atlantic Oscillation. This same weather event affects both Europe and the Eastern US. It seems to fluctuate randomly.
The Atlantic high is called the Pacific/ North American teleconnection pattern (PNA) that is mixed up with the jet stream. It is influenced by El Niño/La Niña events.
Both are involved in the Arctic oscillation and thus determine when and where cold Arctic weather falls lower into the US or Europe. Some of the deepest negative phases ever seen have happened in the last few years.
And this is also one of the areas we need more research. We know that the Arctic Oscillation affects the jet streams and thus our weather. We do not have a precise idea of the effect of climate change on the Arctic Oscillation and the jet stream. As the BBC video states, the effect of melting arctic waters is still an area of current research.