Relation Between Air Temperature and Inland Surface Water Temperature During Climate Change (1961–2014): Case Study of the Polish Lowland

Abstract

The chapter describes the relations between changes in mean annual and mean monthly (1961–2014) air and water temperatures in rivers and lakes, as well as their spatial variability in the Polish Lowland. The determination of the directions and rate of changes in air and water temperatures involved the application of linear regression. Its significance was verified by means of F test at a level of 0.05. The rate of increase in air temperature in the western part of the Polish Lowland was determined to average 0.32 ℃·10 years−1 and decrease towards its eastern part to 0.22 ℃·10 years−1. In the case of rivers, the mean increase in water temperature varied from 0.26 ℃·10 years−1 in the western part to 0.20 ℃·10 years−1 in the eastern part, and for lake waters, from 0.30 to 0.15 ℃·10 years−1. Increase in water temperature in particular months throughout the analysed period was much more variable. Its highest increase occurred in May and ranged in lakes from 3.1 to 3.9 ℃, and in rivers from 1.9 to 2.6 ℃. The lowest increases in water temperature (usually from 0.1 to 1.0 ℃) were observed in autumn and winter months, whereas water temperature in some lakes showed a negative tendency in winter months. In the case of Lake Hancza, in November it decreased during the analysed period by 1.3 ℃. During longer periods such as a year or half-year, an evident increase was found to occur in air and inland water temperature. During shorter month-long periods, the increase is not always so evident, and sometimes even a decrease in temperature is observed.