摘要：The paper presents the analysis of the course of ice phenomena
on four lakes (Lednica, Żnińskie Duże, Biskupińskie, Powidzkie) in central
Poland in the period 1976–2015. The obtained results show changes in their
ice regime that occurred over the last 40 years. An advance of the term of
decline of ice cover was determined (by 2.5 day·dec-1on average for all
lakes), as well as a reduction of duration of ice cover (by 4.4 day·dec-1 on
average for all lakes), and a decrease in its maximum thickness (by 2 cm·dec1
on average for all lakes). Such a situation should be associated with the
observed warming, as confirmed by the course of air temperature for station
Gniezno, where in the period of the winter half-year (November-April), an
increase in temperature was recorded by 0.37°C·dec-1.
其他摘要：The paper presents the analysis of the course of ice phenomena on four lakes (Lednica, Żnińskie Duże, Biskupińskie, Powidzkie) in central Poland in the period 1976–2015. The obtained results show changes in their ice regime that occurred over the last 40 years. An advance of the term of decline of ice cover was determined (by 2.5 day·dec-1on average for all lakes), as well as a reduction of duration of ice cover (by 4.4 day·dec-1 on average for all lakes), and a decrease in its maximum thickness (by 2 cm·dec-1 on average for all lakes). Such a situation should be associated with the observed warming, as confirmed by the course of air temperature for station Gniezno, where in the period of the winter half-year (November-April), an increase in temperature was recorded by 0.37°C·dec-1.
