Wind speeds over the North Atlantic and Europe have decadal changes but no significant trends

The study investigated windiness at monthly scale during 1979-2018 in the North Atlantic and Europe region using ERA5 reanalysis. During the whole 40 year period, the strongest winds occurred over the sea and seasonally during winter time. No significant trends were found in mean and extreme wind speeds but the annual and decadal changes were large. For example, winters in the 1990s in Northern Europe were stormier than average whereas winters in the 1980s and 2010s were windier in Southern Europe.

The decadal wind speed changes are mainly explained by the positioning of the jet stream and storm tracks and the strength of the north-south oriented pressure gradient over the North Atlantic.

“For example in the 1990s, the jet stream and storm track were shifted towards a more northerly path and they extended further east reaching Northern-Eastern Europe,” says Terhi Laurila, research scientist at the Finnish Meteorological Institute.

“In addition, the pressure difference between the northern and southern parts in the North Atlantic was large in the 1990s. These factors led to a stormy decade in Northern Europe”, Laurila continues.

The pressure difference across the North Atlantic is described with the NAO (North Atlantic Oscillation) index which was found to correlate well with the wind speed changes in the North Atlantic and Europe region. In contrast, the AMO (Atlantic Multidecadal Oscillation) index, which describes the sea surface temperature changes in the North Atlantic, was not found to correlate with windiness in Europe, although there was a weak correlation between winds in the North Atlantic and the AMO index.

Wind speed changes are, therefore, related to changes in atmospheric circulation. The study showed that we can obtain more, and broader, information about wind speed changes by investigating long-term variability rather than just analysing linear trends over the whole time period.

Further information:

Research scientist Terhi Laurila, Finnish Meteorological Institute, terhi.laurila@fmi.fi, tel. +358 50 4648812

Reference: Laurila, T.K., V.A. Sinclair, and H. Gregow, 2021: Climatology, variability and trends in near‐surface wind speeds over the North Atlantic and Europe during 1979–2018 based on ERA5. International Journal of Climatology, https://doi.org/10.1002/joc.6957