摘要
[Objective] The study aimed to analyze the changing characteristics of evaporation in Cangzhou City in recent 40 years.[Method] Based the observation data of evaporation measured by small evaporation pans （with the caliber of 20 cm） from weather stations of Cangzhou dur- ing 1971 -2010, the monthly, seasonal, annual and decadal variation of evaporation were analyzed using conventional assessment methods. [Result] During 1971 -2010, monthly average evaporation in Cangzhou fluctuated within a year, and the maximum value appeared in June, while the minimum value appeared in January. Within a year, average evaporation was the highest in summer, and its variation was the greatest; it was the lowest and varied most slightly in winter. During 1971 -2010, evaporation in winter showed an increasing trend, while evaporation showed a de- creasing trend in spring and autumn, and there was no obvious change in evaporation in summer. Annual average evaporation in Cangzhou showed a decreasing trend from 1971 to 2010, and the highest evaporation reached 2 273.3 ram, appearing in 1972. The lowest evaporation was only 1 681.4 mm, appearing in 1990, and the difference between them reached 591.9 mm. Average evaporation in each decade showed a decrease trend, and the maximum value appeared in the 1980s （1 958.6 mm）, while the minimum value appeared in the first ten years of the 21st century （1 880.9 mm）. [ Conclusion] The research could provide theoretical references for studies on climate change in Cangzhou in future.
[Objective] The study aimed to analyze the changing characteristics of evaporation in Cangzhou City in recent 40 years.[Method] Based the observation data of evaporation measured by small evaporation pans （with the caliber of 20 cm） from weather stations of Cangzhou dur- ing 1971 -2010, the monthly, seasonal, annual and decadal variation of evaporation were analyzed using conventional assessment methods. [Result] During 1971 -2010, monthly average evaporation in Cangzhou fluctuated within a year, and the maximum value appeared in June, while the minimum value appeared in January. Within a year, average evaporation was the highest in summer, and its variation was the greatest; it was the lowest and varied most slightly in winter. During 1971 -2010, evaporation in winter showed an increasing trend, while evaporation showed a de- creasing trend in spring and autumn, and there was no obvious change in evaporation in summer. Annual average evaporation in Cangzhou showed a decreasing trend from 1971 to 2010, and the highest evaporation reached 2 273.3 ram, appearing in 1972. The lowest evaporation was only 1 681.4 mm, appearing in 1990, and the difference between them reached 591.9 mm. Average evaporation in each decade showed a decrease trend, and the maximum value appeared in the 1980s （1 958.6 mm）, while the minimum value appeared in the first ten years of the 21st century （1 880.9 mm）. [ Conclusion] The research could provide theoretical references for studies on climate change in Cangzhou in future.
