中文摘要：

在中分辨率成像光谱仪（MODIS）数据产品的基础上,使用MODIS地表温度替代净辐射及蒸散模型中的气温进行计算,并利用兰州大学半干旱气候与环境监测站（SACOL）的实测资料对模型进行修正。将模型修正前后估算的SACOL站和定西干旱气象与生态环境试验站（定西站）的净辐射和蒸散与实测值进行对比。结果表明,MODIS的白天／夜间地表温度与日最高／最低气温之间具有很好的相关性,相关系数都超过0.75,使用其替代气温进行净辐射和蒸散的估算是可行的,且各参数具有明确的物理意义。通过比较模型估算值与地面通量观测站的实测值发现：使用实测资料对模型进行修正后,净辐射和蒸散的估算结果较修正前有了明显的改善。净辐射估算值与实测值之间的均方根误差减小到25.93 W·m^-2;修正后模型估算的SACOL站和定西站蒸散更接近于实测值,均方根误差分别减小到0.81 mm和0.68 mm,相关系数都增加到0.6以上,通过了0.01显著性水平检验;且遥感估算的区域蒸散分布特征与地表覆盖特征相符,说明利用修正后模型估算的净辐射和地表蒸散是合理的,由于这种估算净辐射和蒸散的模型不需要任何实时地面资料的辅助,可以为观测资料缺乏地区的辐射及蒸散研究提供一种新的思路。

英文摘要：

Based on the Moderate-Resolution Imaging Spectroradiometer（MODIS）products,the air temperature in the net radiation and evaportranspiration models were instead by the land surface temperature,and the models were modified using the observed data of Semi-Arid Climate and Environment Observatory of Lanzhou University（SACOL）. Then the net radiation and evapotranspiration estimated by original and modified models were compared with the observed values in SACOL and Dingxi Arid Meteorology and Ecological Environment Experimental Station（Dingxi station）. The results showed that：the MODIS daytime/nighttime land surface temperature was highly correlated with the observed daily maximum／minimum air temperature,and the correlation coefficients were greater than 0. 75,therefore the air temperature in the model can be instead by land surface temperature,and using this method all the parameters in the model have specific physical meanings. Compared to the observations,the modified model improved the accuracy of net radiation and evapotranspiration when used the observed data to modify the model. The root mean square errors of the net radiation by modified models reduced to 25. 93 W·m~（-2）. The evapotranspiration of SACOL and Dingxi stations estimated by the modified model was closer to the measured data,and the root mean square errors were reduced to 0. 81 mm and 0. 68 mm,respectively,and the correlation coefficients were greater than 0. 6,and all passed the 0. 01 level of significance test. Furthermore,the modified model estimated regional evapotranspiration distributions were consistent with the actual land covers of the research area,which implied that the net radiation and evapotranspiration estimated by the modified model was reasonable. Because the modified model only used the remote sensing data without any real- time ground observation,it was a new idea to study the radiation and evapotranspiration in the area where lack of ground measured data.