SHORT-PERIOD TEMPERATURE VARIABILITY AT WINNIPEG, CANADA, 1872-1993 -CHARACTERISTICS AND TRENDS

Temperature variability in Winnipeg, Canada, was assessed by determini ng average and extreme temperature ranges over 1, 2, 5, 10, and 15-day intervals, on a monthly basis, for the period of 1872-1993. Trends in the monthly averages for each of the intervals were also examined. Th e results show that Winnipeg experiences a very large amount of short- term temperature variability, especially over 2, 5, 10 and 15 days. Th e monthly average diurnal ranges vary from about 9 to 14 degrees C , w hile the 15-day average ranges are about two to three times as large. In general, average temperature ranges over the two shortest intervals (1 and 2 days) are slightly greater in the warm-season months than in the cold-season months, but the averages for the three longest interv als are inversely related to mean monthly temperature, as are the larg est ranges observed in each of the months. Average temperature variabi lity in the months of November through March was found to have decreas ed quite significantly, and rapidly, during the first two decades of t his century. This decrease was likely associated with a decrease in th e meridionality of the atmospheric circulation. It also occurred durin g a time when the average maximum and minimum temperatures in Winnipeg were rising, lending support to the conjecture that a warmer global c limate will result in less 1-15 day temperature variability. The rapid ity of the change also supports the hypothesis that climate changes te nd to be non-linear.