Precipitation Trends on the Canadian Prairies

Abstract

The Canadian prairies are a major producer of grain, much of which is produced under rain-fed agriculture. The amount and timing of precipitation are critical to grain production. Information on the precipitation trend is therefore vital to this region. Regression analysis was used to establish linear trends of precipitation amounts, number of precipitation events, and variance of precipitation at 37 stations with 75 yr of record across the Canadian prairies. The precipitation was further split into rainfall and snowfall, and similar analysis was performed on these variables. The analysis showed that there has been a significant increase in the number of precipitation events mainly due to an increase in the number of low-intensity events. As such, precipitation events are not getting more intense on the Canadian prairies. The number of precipitation events (excluding events that are 0.5 mm or less) has increased by 16 events during the last 75 yr. Precipitation and rainfall amounts have increased significantly by 0.62 and 0.60 mm yr?1, respectively, on the Canadian prairies during the last 75 yr. During the period from 1921 to 1960 the trends in precipitation, rainfall, and snowfall were not statistically different from zero. However, from 1961 to 1995, snowfall has declined significantly by 0.95 mm yr?1. The trends in the most recent period (1961?95) were also significantly different from those in the 1921?60 period for snowfall. The difference in trends between the two periods for snowfall, combined with the inverse relationship in the rainfall?snowfall trends, suggest that these trends may be related to climate change.