Trends in evaporation for the Canadian prairies

Trend analyses of evaporation data were conducted for 48 sites on the Canadian Prairies for three analysis periods. Significant trends were identified using the Mann-Kendall statistical test for trend and a bootstrap resampling technique. Trends in calculated evaporation were compared with trends in input variables used to calculate evaporation for all sites and with trends in pan evaporation for four sites. June, July, August, October and warm season evaporation revealed significant trends that were mainly decreasing. The longest analysis period identified an increasing trend in April. Increasing trends were typically in the more northern regions and decreasing trends in the more southern regions. Examining causal mechanisms for evaporation revealed that wind speed had more of an influence on decreasing trends and vapour pressure deficit had more of an influence on increasing trends. (c) 2006 Elsevier B.V. All rights reserved.