2010-2014年祁连山老虎沟流域高寒草甸蒸散发变化特征

Characteristics of evapotranspiration in an alpine meadow in the Laohugou catchment in Qilian Mountains from 2010 to 2014

为估算祁连山老虎沟流域高寒草甸的蒸散发量,利用2010—2014年老虎沟流域自动气象站观测数据,采用Penman-Monteith(P-M)公式首先计算了单点的蒸散发量,再利用Landsat8遥感数据,结合能量平衡系统(SEBS)模型估算了典型晴天条件下流域的蒸散发量,并将估算结果与P-M公式估算结果进行了对比分析。结果表明:研究区高寒草甸5a年蒸散发总量变化幅度较大,平均为205.4mm;各生长阶段蒸散发总量与日均值大小顺序均表现为生长中期>生长后期>生长初期;蒸散发量在7月中旬之前较低,7月中旬之后直到8月下旬最高,8月下旬到生长期结束下降。整个流域的典型晴天遥感日平均蒸散发呈现冰川表面<草地<裸土裸岩石砾地<水域的特征。敏感性实验显示,蒸散发量对相对湿度、净辐射较敏感。

To estimate the evapotranspiration（ET）of an alpine meadow in Laohugou catchment in Qilian mountains,meteorological data of automatic meteorological station from 2010 to 2014 and the Penman-Monteith formula were used in a single observation point.Landsat8 remote sensing data was also used,combined with the surface energy balance system model（SEBS）,to estimate the ET of typical sunny days in the catchment scale.The results show that the annual ET in alpine meadow changes remarkably and the average is 205.4 mm from 2010 to 2014.The order of total and average ET in different growing stages is the middle growing period〉the end growing period〉the initial growing period.The ET is low before mid-July,and it is the highest after mid-July until late August and decreases in late August to the end of the growing season.The daily ET of typical sunny days in the total catchment presents the characteristics of glacier surface 〈grass〈 bare rock and bare soil fertile land〈 waters.Sensitivity experiments show that ET is sensitive to the relative humidity and the net radiation.