GLDAS月降水数据在中国区的适用性评估

Assessing the applicability of GLDAS monthly precipitation data in China

全球陆面数据同化系统(GLDAS)是全球变化与水循环研究的重要数据源之一。对比分析了1979—2012年间GLDAS多套降水数据与中国地面观测逐月降水数据所反映的中国降水趋势变化空间特征,采用相关系数、平均偏差、相对绝对误差和均方根误差4个指标,从时间变化和空间分布特征两个方面,对GLDAS降水数据在中国区域的数据质量进行了系统评估。结果表明:GLDAS-1的几套数据在时间上具有明显不连续性,1996年数据质量严重异常,2000年数据质量也较差,而且,不论是GLDAS-1数据,还是GLDAS-2数据,都存在前期(1979—1995年)与实测数据吻合度高于后期(1997年以后)的现象;GLDAS数据在中国东部湿润区的质量高于在西部干旱区;从相关性与误差指标来看,GLDAS-1数据质量略优于GLDAS-2(主要体现在1995年以前时段),但是GLDAS-2在数据一致性、数据质量季节稳定性及对趋势性描述能力方面则明显优于GLDAS-1数据。

Global Land Data Assimilation System （GLDAS） is an important data source for global change and water cycle research. GLDAS-1 and GLDAS-2 monthly precipitation data during 1979--2012 are compared with Chinese ground-based observations for evaluating their capabilities to detect spatial and temporal changes, and evaluating data quality in terms of correlation coefficient, mean bias error, relative absolute error and root mean square error. The results show that： The quality of GLDAS-1 data sets has a problem of discontinuity, especially serious anomalies in 1996 and poor quality in 2000; the qualities of both GLDAS-1 data and GLDAS-2 data decline during the period from 1979 to 2012 according to their fitness with the observed precipitation data; GLDAS data sets show better quality in eastern China wet areas than in western China arid areas; in terms of correlation and error measures, GLDAS-1 precipitation data are slightly better than GLDAS-2 data （mostly in the period before 1995） , but GLDAS-2 data are significantly superior to GLDAS-1 data in the temporal consistency, seasonal stability and their capability to describe temporal variations.