Spatial diversity of air temperature changes in Poland in 1961–2018

Abstract

The article comprises an analysis of the spatial distribution, and variability of air temperature in Poland in the years 1961–2018. It was found that the mean increase in air temperature was 0.33 °C/10 years. The most evident warming occurred in the west of the country and at the Baltic Sea (> 0.4 °C/10 years). The greatest increase in the temperature was observed in summer (July 0.48 °C/10 years), winter (January 0.46 °C/10 years) and spring (April 0.41 °C/10 years), whereas in autumn the warming was not statistically significant. The major role of atmospheric circulation in shaping air temperature in Poland was corroborated. The positive correlation with the NAO was confirmed, and Pearson’s linear correlation coefficient (r) reached 0.81 in the north of Poland in January. An analysis of the variability of air temperature in Torun (Central Poland) in 1991–2018 demonstrated that the increase in temperature was correlated with a solar irradiance (r = 0.69 in July). Moreover, the types of atmospheric circulation and incoming air masses are also significant. The type of baric centre was found to play a very important role that is opposite in winter to what it is in summer. In cyclonic situations, air temperature increased in winter (r = 0.65 in January) and decreased in the warm half of the year (r = − 0.47 in September). An intensified flow of incoming air masses from the west caused air temperature to increase in winter (r = 0.72 in January) and to cool in summer (r = − 0.69 in August). The role of meridional flow becomes particularly evident in autumn (r = 0.49 in October).