ICE ON LAKE-ONTARIO AT KINGSTON

Observations are reported of freezeup, growth, decay, and breakup of ice during a 10-year period on Lake Ontario at Kingston. The date of freezeup is related to the date on which the running mean air temperature during n days fell to 0-degrees-C where 55 less-than-or-equal-to n less-than-or-equal-to 100 for early and late freezeup respectively. The mean duration of ice cover was 71.7 days (range 18-96 days). Average mean ice thickness was 32 cm and maximum ice thickness in a given year is related to the intensity of cooling measured in degree days of freezing. Breakup normally occurs more rapidly than in smaller, completely ice-covered lakes as a result of the mechanical action of waves and currents. It is estimated that the climatic warming predicted by Global Climate Models will result in little or no ice formation on this part of Lake Ontario. The close response of ice to climatic control while filtering minor fluctuations from the record offers a tool to assess the early stages of climatic warming.