近53a来祁连山南北坡潜在蒸散量及地表湿润度变化趋势分析

Analysis on Potential Evapotranspiration and Surface Moisture Index Change in the South and North Slope of Qilian Mountains in Recent 53 Years

利用祁连山地区15个气象台站1961-2013年月气象资料,计算和分析该地区潜在蒸散量和湿润指数的变化趋势。研究表明：（1）祁连山南北坡潜在蒸散量的年变化表现为单峰型,较大值出现在5-8月,较小值出现在12月至翌年2月。湿润指数从5月开始逐渐增大,南坡7月最大,北坡9月最大,10月开始逐步减小。湿润指数与潜在蒸散量在祁连山地区存在明显的位相差。季节表现均为夏季最大、春秋季次之、冬季最小,潜在蒸散量相邻季节间的波动北坡明显大于南坡,湿润指数则相反;（2）祁连山地区南北坡潜在蒸散量均在波动中呈显著增加趋势,而湿润指数波动中缓慢增加,但变化趋势不明显。潜在蒸散量和湿润指数增加速率均是北坡大于南坡。南北坡潜在蒸散量和湿润指数未来变化趋势总体上将同过去保持一致,且北坡年潜在蒸散量变化趋势强度强于南坡;（3）通过与各气候因子的多元回归分析表明,影响祁连山南北坡湿润指数（潜在蒸散量）的主要因子是降水量（气温）,其他气候因子的变化对地表干湿状况起增强或削弱作用。

Based on meteorological data of 15 observation stations in the Qilian Mountains from 1961 to 2013,the potential evapotranspiration and moisture index there were calculated and analyzed. The results are as follows：（ 1） The annual variation of potential evapotranspiration in the north and south slope of the Qilian Mountains presented a single peak with the larger values occurring from May to August and the smaller values appearing from December to next February. The moisture index increased gradually from May,the maximum occurred in July（ September） in the south（ north） slope,and decreased gradually from October. There was obvious phase difference between moisture index and potential evapotranspiration in the Qilian Mountains area. The potential evapotranspiration and moisture index in summer were larger than those in spring and autumn,which were minimum in winter. The adjacent seasonal fluctuation of potential evapotranspiration in the north slope was significantly greater than that in the south slope,but moisture index was adverse.（ 2） The potential evapotranspiration in the north and south slope of the Qilian Mountains significantly increased,while moisture index increased slowly and the trend was not obvious. The increasing rate of potential evapotranspiration and moisture index in the north slope was faster than that in the south slope. The future trends of potential evapotranspiration and moisture index in the north and south slope would be coherent with the past in general,and the future trend of potential evapotranspiration in the north slope was stronger than that in the south slope.（ 3） The main factor influencing moisture index（ potential evapotranspiration） in the south and north slope was precipitation（ temperature）,and the variation of other meteorological factors enhanced or weakened surface humid state.