CHANGES IN ICE REGIME OF JAGODNE LAKE (NORTH-EASTERN POLAND)

Aim of the study Indication of directions and pace of changes in ice regime of Jagodne Lake in 1975–2015. An analysis of predictability of ice phenomena in relation to stability and seasonality and an understanding mutual interactions between parameters describing ice regime of the lake. Material and methods Data from the Jagodne Małe water gauge station on Jagodne Lake, concerning: the dates of the beginning and the end of ice phenomena, the beginning and the end of ice cover, and the thickness of ice cover from 1975–2015. Average monthly air temperature from the IMGW-PIB synoptic station in Mikołajki. Statistical analysis based on trend analysis using the non-parametric Mann-Kendall test and the Colwell method. Results and conclusions The research has proven that Jagodne Lake shows some tendencies to change in ice regime over the last four decades. These trends should be identified with a successive shortening of ice season and a decrease of the thickness of ice cover. However, these changes in the case of the beginning and the end of ice phenomena (including ice cover) and the thickness of ice cover are not statistically significant. Only shortening of ice phenomena duration was observed and confirmed by the Mann-Kendall statistical test. The analyzed object reacts similarly to most of lakes, for which research on changes in icing was conducted. The observed increase of average temperatures in April had an influence on shortening of ice phenomena.