Interannual variations and trends in surface air temperature in Finland in relation to atmospheric circulation patterns, 1961–2011

Abstract

Annual and seasonal variations in surface air temperature (SAT) during the period 1961-2011 were analysed using daily mean temperature data sets from regular grid points (10 × 10 km 2 ) throughout Finland. The Mann-Kendall nonparametric test was used to detect significant historical trends in SAT and Spearman's correlation coefficient ( ) to test the relationships between SAT patterns and various atmospheric circulation patterns over the northern hemisphere. The results showed that mean annual SAT in Finland increased (p < 0.05) by 0.4 ± 0.2 ∘ C per decade during the study period and that the SAT was significantly ( = 0.58, p < 0.05) positively correlated with the Arctic Oscillation (AO) index. However, there were spatial differences within Finland for both the trends and relationships with the atmospheric circulation. Analysis of seasonal mean SAT identified significant (p < 0.05) warming trends for both spring (by 0.4 ± 0.2 ∘ C per decade) and summer (by 0.3 ± 0.2 ∘ C per decade). Winter and spring mean SATs were most strongly (p < 0.05) correlated with the AO index ( = 0.72 and 0.42, respectively), while the most significant teleconnection pattern for mean SAT in summer was the East Atlantic (EA) pattern ( = 0.43, p < 0.05); and in autumn the EA/West Russia (WR) pattern ( = −0.59, p < 0.05). These results provide a detailed spatial picture of climate warming in Finland in recent decades and reveal that interannual variation of the SAT in Finland is closely linked with a number of atmospheric circulation patterns, not just the AO and North Atlantic Oscillation (NAO). Annual and cold-season SAT are mainly influenced by the AO and NAO, whereas the EA, EA/WR, Scandinavia (SCA) and West Pacific (WP) patterns play an important role for warm-season SAT.

Warm spells in Northern Europe in relation to atmospheric circulation

“…According to The BACC Author Team (Assessment of Climate Change… 2008; Wójcik and Miętus 2014), the warming within the Baltic Sea region is progressing faster than on the global scale. As Tietäväinen et al (2010) displayed that between 1909 and 2008 in Finland, the increase in the mean annual air temperature was 0.093 ± 0.072°C/decade, whereas between 1961 and 2011, the increase was 0.4 ± 0.2°C/decade (Irannezhad et al 2014). A similar trend in air temperature changes was also confirmed in Norway.…”

Can tree-ring density data reflect summer temperature extremes and associated circulation patterns over Fennoscandia?

“…Climate in the north is characterized by harsh winters with a long-lasting snow cover and a short growing season in summer, while climate in the south is featured by mild winters with little or no snow cover, and longer growing season (Linderholm 2006;Linderholm et al 2008). Climate variability in this region is influenced by a number of circulation patterns in summer such as the East Atlantic, Western Russia and Scandinavia patterns (Irannezhad et al 2015) and the North Atlantic Oscillation (NAO) on interannual-to-decadal time scales (Hurrell 1995;Rogers 1997;Chen and Hellström 1999;Busuioc et al 2001;Folland et al 2009). North Atlantic sea surface temperature (SST) also plays a role on decadal to centennial time scales (Dima and Lohmann 2007).…”

Observed Regional Climate Variability during the Last 50 Years in Reindeer Herding Cooperatives of Finnish Fell Lapland

“…While the higher sensitivity of northern latitudes, compared to most other parts of the world, to climate change has been shown [1, 7,8], few multidisciplinary studies have undertaken quantitative climate research in specific remote and vulnerable areas of Finnish Lapland [9]. Also, most of the studies conducted in Finland focus on the long-term variability of one single climate variable at local-scale [10] or national-scale [11,12], whereas the present one attempts to investigate the long-term and local-scale variability of all climate variables that are specifically crucial for reindeer herding.…”