夏季黑河流域蒸散发量卫星遥感估算研究

依据空气动力学方法和蒸散发量时间尺度扩展方案,利用MODIS资料和气象资料,计算中国西北内陆河黑河流域复杂地形下,2004年夏季7月蒸散发量空间分布及总量。利用Landsat-5TM资料对比分析发现,估算地表水热传输过程时,采用高分辨率遥感资料的估算结果受下垫面非均匀性影响程度,明显小于采用中分辨率资料。通过金塔实验湍流观测资料验证表明,利用高分辨率资料估算日蒸散发量的相对误差在10%以内。对月蒸散发量计算分析表明,黑河流域海拔2000m以上祁连山区,7月平均蒸散发量是海拔2000m以下山前地区的2.2倍,而山前平原区绿洲(NDVI>0.10区域)平均蒸散发量又是荒漠戈壁地区的12.3倍。因此,流域中下游绿洲地区特别是农业灌溉区是夏季主要水资源消耗区。

Estimation of summer evapotranspiration using satellite remote sensing data over the Heihe river basin

In this paper,the distribution and total amount of evapotranspiration (ET) is estimated under the diverse landscape over the Heihe river basin in Northwestern China in July 2004 by using MODIS data and meteorological data based on the aerodynamic method and the time upscaling scheme.Taking advantage of the high resolution Landsat-TM data,according to the contrastive analysis,we find that the influence of the heterogeneous underlying earth's surface on the estimation of water and heat exchange on the land surface by using the high resolution remote sensing data is obviously smaller than that by using the middle resolution ones.By comparing the estimates of ET with the observation data collected from JTEX experiment we conclude that,by using the high resolution data,the parameterization algorithm used in this paper can derive daily ET with a relative error of 10%.After analyzing the distribution of the derived monthly ET over the basin in July 2004,it is concluded that the mountainous area above 2000 m exhibits the ET twice more than that the area fronting mountains below 2000 m elevation; and the oasis and crop area take on an ET 12 times more than that of the desert and Gobi region over the area fronting mountains,and the former is the most significant region that consumes land surface water over the mid-downstream area in summer.