[Objective] The research aimed to study the variation characteristics of pan evaporation and its influence factors in Qinghai Lake basin during 1961 -2007. [Method] By using the climate tendency rate method, the variation characteristics of small pan evaporation (20 cm) and its influence factors in Qinghai Lake basin during 1961 -2007 were analyzed. [Result] In recent 47 years, the pan evaporation in Qinghai Lake basin presented the decreasing trend, and the tendency rate was -47.75 mm/10a. Except in autumn, the pan evaporations in other seasons decreased at 7. 33 - 19.57 mm/10a rate. Spring decreasing range was the maximum, and winter decreasing range was the minimum. For the space characteristics of variation trend, except in Cangcha station, the annual pan evaporations in other stations of Qinghai Lake basin all presented the decreasing trend, and the decreasing range was during 32.36 -75.63 mm/10a. The decreasing range of pan evaporation decreased as the longitude increasing. The sunshine hours which affected the pan evaporation presented the significant declining trend, . And the rainfall presented the significant increasing trend. The average temperature significantly rose. The rising rate of average minimum temperature was bigger than that of average maximum temperature, and the diurnal temperature decreased, which also had the influence on the e-vaporation. [ Conclusion] The research had the important significances for better understanding the response of Qinghai Lake basin to the climate warming and the water resource management in the zone.%[目的]研究青海湖流域1961 ～2007年蒸发皿蒸发量及其影响因素的变化特征.[方法]采用气候倾向率方法,对青海湖流域1961 ～2007年20 cm小型蒸发皿蒸发量及其影响气候因子的变化趋势进行了分析.[结果]近47年来,青海湖流域的蒸发皿蒸发量呈现出减少的趋势,倾向率为-47.75 mm/10a.各季节的蒸发量除秋季没有变化外,其他各季以7.33～19.57 mm/10a的速率减小,其中春季减幅最大,冬季减幅最小；就变化趋势的空间特征而言,青海湖流域各站的年蒸发皿蒸发量除刚察站外,其他各站均表现为不同程度的减少趋势,减幅为32.36 ～75.63mm/10a.蒸发皿蒸发量的减少幅度随着经度的增加而减少.影响蒸发皿蒸发量的日照时数呈显著下降趋势,夏季降水量显著增加,平均气温显著升高,平均最低气温的升高速率比平均最高气温的升高速率大,导致气温日较差减小,对蒸发也会产生影响.[结论]该研究对更好地了解青海湖流域对气候变化的响应以及该区域的水资源管理均具有十分重要的意义.
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