利用GRACE模型反演长江流域陆地水储量的变化

Terrestrial water storage variations in Yangtze River Basin based on Tongji-Grace 2018 Temporal Gravity Field Model

长江流域是我国重要的经济区域,分析其陆地水储量变化对研究气候变化及安排农业生产、防治旱涝灾害等具有重要的意义。利用同济大学最新解算的GRACE时变重力场模型Tongji-Grace2018,采用去相关滤波P4M6和300 km扇形滤波进行预处理,来反演长江流域2003年1月至2016年8月的陆地水储量变化(TWSC,terrestrial water storage change)并分析其时空分布特性,同时将其反演结果与CSR RL06模型的反演结果进行了对比。研究结果表明:①长江流域陆地水储量变化呈上升的趋势且季节性特征明显;Tongji-Grace2018模型反演的时段内长期趋势变化速率为0.58 cm/a,周年振幅为4.23 cm;CSR RL06模型反演得到的长期趋势变化速率为0.63 cm/a,周年振幅为4.04 cm。由此可见,Tongji-Grace2018模型反演的质量变化信号更明显。②在空间分布上,两种模型反演的长江流域水储量变化均表现出了中游和下游大、上游小的特征。③从季节角度分析可知,水储量夏季盈余,春冬季亏损,秋季变化基本平衡。此外,流域内的各省中,湖南和江西两省的水储量变化的周年振幅和趋势最大,分别约为6 cm/a和1 cm/a。研究成果对合理调配水资源具有重要的意义。

Yangtze River Basin is one of the most important economic zone in our country.Therefore,it is significant to analyze TWSC(terrestrial water storage change)in this region which is meaningful in studying climate change,arranging agricultural production and preventing droughts and floods disaster in the basin.In this paper,the Tongji-Grace2018 model released by Tongji University recently was employed,which was filtered by the combination of decorrelation in P4M6 and fan filter with a radius of 300 km.We calculated TWSC and analyzed its spatial-temporal variations from January in 2013 to August in 2016.As a comparison,CSR RL06 was also used to derive the TWSC.The specific results are as follows:the TWSC in Yangtze River Basin is on the rise with apparent seasonal characteristics.The linear trend and annual amplitude of TWSC series derived by Tongji-Grace2018 are 0.58 cm/a and 4.23 cm,whereas those for CSR RL06 are 0.63 cm/a and 4.04 cm,respectively.It is obvious that Tongji-Grace2018 can extract more signals than CSR RL06.In terms of spatial distribution,the TWSC in the Yangtze River Basin estimated by the two models are all larger in the middle and lower reaches and smaller in the upper reaches.From the perspective of the seasonal variation,the TWS has a surplus in summer,a loss in spring and winter,and a balance in autumn.For Hunan and Jiangxi Provinces,the linear trend and annual amplitude of TWSC are the highest and largest among all the provinces of this basin,which are 1 cm/a and 6 cm respectively.