A summer temperature proxy from height increment of Scots pine since 1561 at the northern timberline in Fennoscandia

Abstract

Height increments of 60 Scots pine trees were used to reconstruct mean June—August temperature variability at interannual to decadal scales from 1561 to 2004. Three standardization methods (67%, 33% flexible splines, and a fixed 22 years spline) were compared in building chronologies in order to optimize the frequency response in relation to major climatic forcing factors. The height-growth chronology built using the 33% spline standardization proved to have the most consistent and time-stable relationship with the summer temperatures. Among the monthly precipitation and temperature variables from previous June to current August, previous July shows the highest correlation with height growth. In addition, both previous June and previous August have significant positive correlations. Our final transfer model accounts for 32.5% of the dependent instrumental temperature variance between 1909 and 2004. The Fourier spectra of the height-growth chronology and mean summer temperature are very similar in appearance, both series having peaks at 2.7—3.2 years, 6.7 years and 15.7 years. Thus, the 444 years long summer temperature reconstruction is limited to high and medium frequencies. The coldest three summers in this record were experienced in years 1601, 1790 and 1903. Correspondingly, the summers of 1626, 1689 and 1598 were the warmest. The 1820s experienced the warmest 10-year mean, while the first decade of the twentieth century was the coldest. Among the 14 non-overlapping 30-year periods between 1561 and 1980, the period 1621—1650 was the warmest and the period 1591—1620 the coldest.

Six Temperature Proxies of Scots Pine from the Interior of Northern Fennoscandia Combined in Three Frequency Ranges

“…The others are smaller, consisting of samples from 167 (FHI) to 78 trees (FXD). Height data (FHI) are shifted by one year for making comparisons possible, because height growth reflects conditions in the previous year [25,26].…”

Documentary evidence of historical floods and extreme rainfall events in Sweden 1400–1800

“…In a number of studies the great variability in flood frequencies in Europe has been explained by large-scale atmospheric circulation patterns, particularly on a decadal timescale (Schmocker-Fackel and Naef, 2010;Casanueva et al, 2014). In particular, the NAO together with other, related atmospheric circulation patterns is normally seen as the main explanation for climatic variability in northern Europe (Lindholm et al, 2009), especially winter precipitation in the NAO positive phases (Hurrell and Van Loon, 1997;Barker et al, 2004;Casanueva et al, 2014) as well as for river discharges, snow accumulation and flooding (Prudhomme and Genevier, 2011). However, there is no clear connection between the existing NAO reconstructions and flood frequency in Sweden.…”

“…For example, it seems that NAO-related precipitation patterns east of the Scandinavian mountains, i.e. in Sweden, are overplayed by other climatic factors (Uvo, 2003;Linderholm et al, 2003). However, it is conspicuous that the great majority of the worst flood events have been recorded in catchments that are particularly subjected to spring floods fuelled by melting snow from high altitudes or latitudes (Norrström, Göta älv, Dalälven, Torneälven, Piteälven, Ljungan, Indalsälven) and where lake evapotranspiration is lower and water storage capacity higher (see Fig.…”

Inter- and intra-annual dynamics of height increment in young beech and spruce stands in relation to tree size and weather conditions

“…A clear effect of air temperature on current-year height increment was shown by a variety of papers that usually refer to early summer weeks of the previous year (e.g. Salminen & Jalkanen 2005;Lindholm et al 2009) or summer weeks of the current year (Gamache & Payette 2004;Salmine & Jalkanen 2004), eventually summer temperatures in both previous and current years (Wang et al 2012). These interactions might be related to the fact that shoot extension of most tree species is a 2-year-process involving firstly the formation of terminal buds and then shoot elongation itself (Kozlowski 1964).…”