Long-term characteristics of ice phenology in Karelian lakes

The statistical relationships between lake ice phenology (freeze and break-up dates, ice duration), air temperature and North Atlantic Oscillation (NAO) index are analysed for eight lakes in Karelia from 1950 to 2009. Linear trends over this time period are estimated. It is shown that in the last 20 years trends in the timing of ice phenomena are more evident than in the entire 60-year period. The statistical relationship between lake ice phenology and variability of regional air temperature is used in the empirical model to assess ice-related events on previously unstudied lakes in NW Russia.