A unique analysis of the Swedish wind climate over a period of more than 100 years has been carried out by SMHI. The study shows that the winds vary greatly between different areas and between different periods.
"The natural cycles are rather long, often around 10 years or more. That is why very long time series with observations are needed in order to be able to see more permanent changes and trends in the wind climate," says climate researcher Lars Bärring at SMHI.
The results show large variations, but over the past 60 years, the change has in general meant slightly weaker winds. This reduction in average wind speeds and energy content is more pronounced in the North. All in all for the entire country, the potential wind energy has reduced by 7%.
Wind calculations have been carried out based on observations of air pressure. The analysis encompasses wind data for 11 areas throughout the country and relates to so-called geostrophic wind. This is an estimated value of the large-scale regional wind speed, without local topography or other wind-dampening factors such as forest, buildings etc having any influence. Such factors often change over time and can have a major influence on the local wind climate.
What governs the wind climate in the long term is the large-scale circulation in the atmosphere, which is determined by large-scale differences in air pressure. This in turn is controlled by temperature differences between southern and northern latitudes.
The connection between the wind climate and the large-scale temperature distribution is however complicated. That is why there is still no consensus of opinion in science as to how the wind climate in Scandinavia and Europe will develop in the future.
The analysis of the wind climate provides a clear historical picture and will also provide valuable support to interpret future scenarios.