联合GRACE重力卫星与实测资料估计西辽河流域蒸散发量

Evaluation of the Evapotranspiration in the West Liaohe River Basin Based on GRACE Satellite and in Situ Measurements

西辽河流域是中国气候变化最敏感的区域之一,2000年以来,该区域水资源短缺日趋严重。基于水量平衡方程,联合重力卫星、降水资料和径流资料估计了西辽河流域的实际蒸散发量,并与遥感蒸散发产品和水文模式的蒸散发结果进行了对比分析。结果表明,在2005—2011年的干旱期,该流域平均年累计蒸散发量比同时期年降水量高了9.8 mm,多出的蒸散发主要来自于地下水亏损的贡献(约6.8 mm/a)。基于卫星重力的水量平衡方法可以有效估计干旱期由于地下水亏损导致的蒸散发增加。遥感蒸散发产品均明显低估了西辽河流域的实际蒸散发,而GLDAS-2.1 Noah模式明显高估了该区域的蒸散发量。基于卫星重力可以估计西辽河流域的蒸散发,并可用于评估不同的蒸散发产品。

The West Liaohe River Basin(WLRB)is one of the most sensitive areas to climate change in China.Here we use the terrestrial water fluxes derived from the Gravity Recovery and Climate Experiment(GRACE)satellites,precipitation dataset,and in situ runoff records,to calculate the actual evapotranspiration(ET)in the WLRB based on the water balance equation.We find that during the drought period of 2005—2011,the mean annual ET is 350.5 mm,which is 9.8 mm more than the mean annual precipitation during the same time period.This difference can be explained by the groundwater depletion in the WLRB(about 6.8 mm/a).We also find that the ET products from remote sensing both underestimate the actual ET in the WLRB,compared with the GRACE-based ET results.However,the ET simulated by the global land data assimilation system version 2.1(GLDAS-2.1)Noah is overestimated.This paper highlights the capability of GRACE to monitor actual ET in the WLRB and to validate different ET products from remote sensing and models.