Effect of Northern Hemisphere Teleconnections on the Hydropower Production in Southern Sweden

Approximately 50% of Sweden's electricity is produced by hydropower. This makes energy production in the country vulnerable to factors affecting water availability. Research has shown a positive correlation between the North Atlantic Oscillation (NAO) and hydropower production in Norway and northern Sweden during winter months. The correlation is, however, weaker in southern Sweden, which indicates that there might be other low-frequency atmospheric drivers (teleconnections) affecting this area. The aim of this paper is to analyze the natural climate forcing that affects hydropower production in southern Sweden on a seasonal basis. This knowledge may be of key importance in improving long-term (seasonal to yearly) water management and planning for electricity production in southern Sweden. The Spearman correlation coefficient was calculated between the principal component time series of electricity production (1999-2010) from 17 hydropower stations in 5 different rivers located in southern Sweden and 5 different teleconnection indices: the NAO, East Atlantic (EA), East Atlantic/Western Russia (EA/WR), Scandinavia (SCA), and Polar/Eurasia (POL). Results show that the impact of teleconnections on hydropower electricity production varies with season. In winter, the NAO shows the strongest positive relation with hydropower electricity production, explaining 24% of the variability in production, while the SCA has an almost as strong (15%) opposite effect. During spring and summer, the EA/WR alone shows a significant negative relation, explaining respectively 9 and 13% of the variance in production. No significant correlation appeared during the fall season. (C) 2015 American Society of Civil Engineers.