石羊河流域近53a参考作物蒸散量的敏感性分析

Sensitivity Analysis of Reference Crop Evapotranspiration in Shiyang River Basin in Recent 53Years

利用国家气象信息中心提供的地面气候资料日值数据集,基于FAO Penman—Monteith公式计算了石羊河流域4个测站1959—2011年的逐日参考作物蒸散量(ET0)。利用敏感系数法计算了其对平均最高气温、平均最低气温、风速、平均相对湿度和日照时数的敏感系数,并分析了敏感系数的时空变化特征。结果表明,石羊河流域ET0对相对湿度最敏感,其次为风速和气温,而对日照时数的敏感性最低。由于气象要素分布不均,敏感系数的空间差异显著,相对湿度的敏感系数在上游祁连山区形成高值区,同时,气温在该区的敏感系数也相对较大,而风速的敏感系数在下游民勤盆地较大,日照时数的敏感系数在全区无明显差异。各气象因子的敏感系数均存在一定程度的波动,风速的敏感系数冬高夏低,气温和日照时数的敏感系数均为夏季最高,相对湿度敏感系数的绝对值持续上升在秋季达到最大。53a来,相对湿度敏感系数波动变化,近20a来其绝对值上升趋势显著,而风速、日照时数和气温的敏感系数无明显变化趋势。

The sensitivity coefficients of daily reference evapotranspiration （ET0） to average temperature, wind speed, relative humidity and sunshine hours in the Shiyang River basin during 1959--2011 were calculated by using Penman--Monteith equation recommended by FAO, based on daily meteorological data provided by the China Meteorological Administer. Moreover, temporal variations of the sensitivity coefficients were analyzed. Results show that relative humidity was the most sensitive factor of ET0 in the Shiyang River basin, wind speed and temperature were in the second place, and sunshine hours had the lowest sensitivity. Because of climate factors contrast and significant spatial difference of the sensitive coefficients, the sensitive coefficient of relative humidity formed high value area in the upstream area of the Qilian Mountains. Mean- while, the sensitive coefficient of temperature was relatively large. But the sensitive coefficient of wind speed was the largest in the downstream area of the Minqin basin. The sensitive coefficient of sunshine hours had no significant difference in all the areas. The sensitive coefficient of each of the meteorological factors showed a certain degree of volatility. Wind speed was high in winter, but low in summer; temperature and sunshine hours were all high in summer; and the absolute value of relative humidity continued to rise to the maximum in fall. The sensitive coefficient of relative humidity fluctuated in the past 53 years, absolute value showed a significant upward trend, but the wind speed, sunshine hours and temperature had no obvious trend in the last 20 years.