利用卫星观测数据评估GLDAS与WGHM水文模型的适用性

Using Satellite Observations to Assess Applicability of GLDAS and WGHM Hydrological Model

  • 摘要: 利用2002—2012年的GLDAS和WGHM模型模拟水文产品,以及重力恢复与气候试验卫星(Gravity Recovery and Climate Experiment,GRACE)观测数据,计算了全球范围内30个主要流域的水储量变化时间序列,从模拟数据与观测数据的年周期振幅、长期趋势项及时空分布一致性等几个方面,对GLDAS和WGHM进行了评估。结果表明,GLDAS的4个子模型都表现出了明显的季节性变化,CLM年周期振幅输出最小,MOSAIC和VIC最大,NOAH居中,且最接近4个子模型的平均值。与GRACE结果相比,约80%流域的GLDAS与WGHM模型年周期振幅输出呈明显低估现象,且GLDAS的低估程度大于WGHM,但靠近北极高纬度地区的流域有相反的情况出现。在长期趋势项方面,三者结果差异较大,尤其是对于面积较小且人类活动影响较大的流域,GLDAS与WGHM模型不能充分反映人类活动的影响,模型输出表现较差,GRACE结果更接近实际情况。此外,还研究了流域水储量长期变化趋势与灌溉率的关系,发现呈现明显下降趋势的流域主要集中在高灌溉率(>10%)地区,而灌溉率是影响流域水储量变化的重要因素之一。

     

    Abstract: GLDAS and WGHM hydrological products from January 2002 to December 2012 are investigated with GRACE satellite observations to study the terrestrial water storage anomalies (TWSA) in 30 major river basins worldwide. GLDAS and WGHM model outputs are compared and evaluated in terms of annual amplitude, long-term trend and spatial-temporal consistency with GRACE observations. The results show that the four land surface models in GLDAS show an obvious seasonal cycle in TWSA, among which the amplitudes of CLM is the smallest, MOSAIC and VIC are largest, and NOAH is in middle which exhibits the strongest consistency to the average GLDAS estimates. Compared with the GRACE results, the annual amplitudes are obviously underestimated by both GLDAS and WGHM in most river basins, and the underestimation degree of GLDAS is greater than that of WGHM. Also, the opposite situation occurs in river basins located near the Arctic. In terms of long-term trend, the results of the three models are quite different, especially for river basin with small area and strong human intervention, GLDAS and WGHM are not capable enough of reflecting the impact of human activities and their output performances are poor, while the GRACE results are closer to the actual situation. It is also found that the river basins with obvious downward trends are mainly concentrated in the areas with high irrigation rate (>10%).

     

/

返回文章
返回