Author(s): Johanna Korhonen

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Keywords: Lakes; Break-up; Freezing; Ice thickness; Trends

Abstract: The longest ice break-up series in Finland started in spring 1693 (river Tornionjoki) and freezing and break-up records are available at least since the mid-19th century from three lakes - Kallavesi, Nasijarvi and Oulujarvi. The number of time series starting in the late 19th century amounts to at least twenty. A large number of ice observations were analysed in order to identify long-term changes in the ice regime. The analysis clearly showed that there is a statistically significant change towards earlier ice break-up in Finland, from the late 19th century to the present time. There is also a significant trend towards later freezing in the longest series and thus also towards a shorter ice cover duration. The series of maximum thickness of ice showed both decreasing and increasing trends. These trends were statistically significant for approximately half of the observation sites. Decreasing maximum ice thickness trends were found in the southern part of the country and increasing trends in central and northern regions.

DOI:

Year: 2006