中文摘要：

利用位于藏北高原季节性冻土区的MS3478自动气象站的观测资料，基于FAO推荐的Pen—man—Monteith方法，分析了该地区的潜在蒸散量的变化特征。讨论了动力、热力和水分因子对潜在蒸散的影响，并分析了该地区的干湿状况。结果表明：全年日潜在蒸散量在0．52～6．46mm之间；夏季蒸发力最旺盛，5～9月的月潜在蒸散量均超过了100mm，11月份潜在蒸散锐减至33mm，潜在蒸散年总量为1037．83mm；夏季热力蒸散量明显大于动力蒸散，而冬季动力蒸散明显大于热力蒸散。藏北冻土区仅在5～9月为半湿润气候，持续时间较短，冬半年的干旱和半干旱维持时间长。水分因子和动力因子对潜在蒸散的影响季节变化大。土壤水分不是影响潜在蒸散的主要因素。

英文摘要：

Based on the observed data at Automatic Weather Site（AWS） of MS3478 in the seasonal frozen soil region of northern Tibetan Plateau from March 2007 to February 2008. The variation characteristics of potential evapotranspiration （PE） was analyzed based on Penman-Monteith method recommended by FAO. The contributions of dynamic, thermal and water factors to PE were discussed. Meanwhile, the wet-dry conditions of that region was further studied. The results indicated that the daily PE was between 0.52 mm and 6.46 mm in the whole year. In summer, the evaporation was the most intensive, and month PE from May to September was over 100 mm. In November, there was a clear mutant. Annual potential evapotranspiration was 1037.83 mm. In summer, thermal evapotranspiration was much more significantly than dynamic evapotranspiration; in winter it was on the contrary. In addition, the drought and semidrought climate lasted for a long time while semi-humid climate short. The effect of water and dynamic factors on PE varied considerably with the season. Soil moisture was not the main factor affected PE.