陆面蒸散发是地表水循环和能量循环的重要组成部分,准确的估算蒸散发对区域气候研究和干旱监测有重要意义。利用公用陆面过程模式CLM 4.0模式输出的高时间分辨率的净辐射、地表温度作为遥感经验模型的输入,结合SACOL站观测资料估算了西北半干旱区的陆面蒸散发,并将估算值与观测值进行了对比分析。结果 表明:CLM模式对净辐射、地表温度的模拟性能较理想,与观测值的RMSE,MAPE相对较小,相关性更高。遥感经验模型估算的SACOL站陆面蒸散发与实测值的偏差较小,CLM模式模拟的蒸散发与观测值的一致性较好,但模式较观测值偏大。基于CLM模式模拟得到更为准确的净辐射、地表温度和NDVI估算得到的蒸散发与观测值的变化趋势较为一致,两者的误差较小,相关性更好,对半干旱区蒸散发的估算精度有显著提高,且能够得到更高时间分辨率的陆面蒸散发。
Land surface evapotranspiration is an important component of surface water and energy cycle. Accurate estimation of land surface evapotranspiration is of great significance to regional climate research and drought monitoring. We used the high temporal resolution net radiation and surface temperature simulated by CLM as the input of the remote sensing empirical statistical model(EMP)to estimate terrestrial evapotranspiration in the semi-arid region of Northwest China based on the observation data of Semi-Arid Climate Observatory and Laboratory of Lanzhou University(SACOL). Compared with the observed values, the results showed that the simulation performance of CLM for net radiation and surface temperature was ideal, the RMSE, MAPE of the net radiation and surface temperature simulated by CLM were relatively small, and the correlation was closer; the deviation between evapotranspiration estimated by EMP and measured values was small; the evapotranspiration simulated by CLM model was in good agreement with the observed values, but the values were larger than the observed values; the trend of evapotranspiration obtained by EMP_CLM which proposed by more accurate net radiation and surface temperature simulated by CLM and NDVI was more consistent with the observed values; the deviation between the two was smaller and the correlation was better. The estimation accuracy of evapotranspiration in semi-arid region was significantly improved, and higher temporal resolution evapotranspiration can be obtained. Generally speaking, the new method can improve the estimation performance of evapotranspiration in semi-arid area.
