Impact of climate change on winter precipitation regimes across Ontario

The goal of this thesis lies in the identification of possible significant trends in winter temperature and precipitation across Ontario. In this study the trends and variations in several indices of daily winter temperature and precipitation were explored applying least squares regressions and Mann-Kendall test for 13 stations located across Ontario for the period 1939 to 2008. Correlation analysis was also used to detect possible link between winter temperature and winter precipitation variables. Datasets were supplied by Environment Canada. The analysis of the temperature indices indicates a significant upward trend in winter temperature values. Also the analysis of the precipitation indices reveals no significant trend in the winter total precipitation series, decreasing trends in winter snowfall, and increasing trends in winter rainfall. This analysis showed that there has been a significant increase in the number of rainy days, but no significant trend has been detected in the number of snowy days. A downward trend in winter snowfall as a percentage of winter precipitation (S/P), and an upward trend in winter rainfall as a percentage of winter precipitation (R/P) have also been detected. The downward trend in winter S/P is linked to the decreasing trend in the winter snowfall, and the upward trend in R/P is linked to the rising trend in winter rainfall. The trends in inter rainfall and snowfall were found to be correlated with the trend in winter temperatures.