Annual and seasonal mean temperatures in Finland during the last 160 years based on gridded temperature data

Abstract

ABSTRACT:The annual and seasonal mean temperature of Finland was calculated for 162 years based on spatially interpolated monthly mean temperature records. The spatial interpolation method, known as kriging, was used with the following forcing parameters: the geographical coordinates, elevation of the terrain, and percentage share of lakes and sea. Homogenised data was used, and thus the most important factor affecting the accuracy of the interpolated data was the uneven distribution of the available observation stations both in time and space. The uncertainty due to the homogenisation adjustments made earlier was notably smaller. In the mid-1800s, the uncertainty in the annual and seasonal mean temperatures was large, with a maximum in winter of over ±2.0°C, but the accuracy improved quickly with time as the number of the observation stations increased. At the beginning of the 20th century, the uncertainty related to the limited station network was less than ±0.2°C, in winter less than ±0.4°C. According to the data, the rise in Finland's annual mean temperature has been statistically significant during the last 100, 50 and 30 years. During the last 100 years the increase in the mean temperature was largest during spring, but during the last 50 years winters have warmed up the most. The temperature time series obtained are compatible with grid point values picked from the global temperature data grids starting from the 1880s, though the global data sets tend to smooth the extremes.

Sodankylä manual snow survey program

“…Synoptic weather observations have been made in Sodankylä since 1908 (Tietäväinen et al, 2010), first in the town centre and since 1913 at the current research station area. Today two institutes share the station: Sodankylä Geophysical Observatory (SGO), which was established in 1913 as Magnetic Observatory and is presently part of the Oulu University, and FMI observatory, which was established in 1949 and continues the meteorological data records at the site.…”

A palaeotemperature record for the Finnish Lakeland based on microdensitometric variations in tree rings

“…In order to obtain the longest possible temperature time series for the study area, the Finnish monthly mean temperature grid data (Tietäväinen et al, 2010) was used to estimate the mean monthly temperatures for a grid point representing the site of the Punkaharju meteorological station. The grid data provides temperature values for the site since the year AD 1883.…”

Recent Change—Atmosphere

“…A number of studies show similar warming trends for areas of the Baltic Sea basin and its vicinity: Finland (Tietäväinen et al 2009 (Brázdil et al 2009), Latvia Klavinš and Rodinov 2010), Estonia (Kont et al 2007(Kont et al , 2011Russak 2009) and for the three Baltic countries together (Kriauciuniene et al 2012). Long and homogeneous time series of spatial mean air temperature were created for Finland covering 1847-2008 (Tietäväinen et al 2009). Trends were calculated for three periods: 1909-2008, 1959-2008 and 1979-2008.…”