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地球重力场季节和年际变化主要来源于地球表层大气、海洋和陆地各系统间水的质量交换,由GRACE重力卫星探测地球重力场变化所反映陆地水储量的改变主要来自降雨、土壤蒸发蒸腾、河流输运以及向地下深层的渗透等过程.本研究利用陆面过程模式CLM3.5以及基于本征正交分解的集合四维变分同化方法 PODEn4DVar,构建能够同化GRACE卫星重力场的陆面水文同化系统LDAS-G,实现对地球重力场所反映的大尺度陆地水储量变化在时间及垂直方向各分量的分解,并对垂直方向的水文变量进行同化,从而更好地估计陆面水循环要素变化并实现其监测.利用LDAS-G同化系统进行理想试验以及针对中国区域所进行的同化试验表明该同化系统能够改善对陆面水文要素变化的模拟,对大尺度陆面水文循环监测研究具有重要意义.
The seasonal and interannual variations of the Earth’s gravitational field mainly come from the mass exchange of water between the Earth’s surface atmosphere, the ocean and the terrestrial systems. The changes of the gravitational field of the Earth reflected by the GRACE gravity satellite mainly reflect rainfall, soil evapotranspiration, River transport and penetration into the deep underground.In this study, land surface process model CLM3.5 and the set of four-dimensional variational assimilation method PODEn4DVar based on eigen-orthogonal decomposition were used to construct a land surface hydrological assimilation The system LDAS-G realizes the decomposition of large-scale terrestrial water reserves in the time and the vertical direction reflected by the Earth’s gravitational field and assimilates the hydrological variables in the vertical direction to better estimate and implement Its monitoring.The ideal experiment with LDAS-G assimilation system and the assimilation test conducted in China show that the assimilation system can improve the simulation of the hydrological elements on the land surface, which is of great significance to the large-scale monitoring of the hydrological cycle on the land surface.