顾及GRACE季节影响的华北平原水储量变化反演

基于移去-恢复方法，利用GRACE卫星重力数据研究了华北平原2003年1月—2014年6月的陆地水变化，提出了一种顾及季节影响尺度因子计算方法，用于减小GRACE后处理误差。将本文方法所得结果与水文模式和降水模型结合进行比较分析，结果表明：2008年之前华北平原发生比较明显的干旱现象，陆地水和地表水分别以（-7.9±2.4）mm/a和（-7.3±2.8）mm/a的速度下降，但地下水仅以（-0.6±1.4）mm/a的速度减少；2008年之后，陆地水和地表水分别以（4.3±1.3）mm/a和（10.9±2.1）mm/a的速度上升，期间地下水的超采严重，平均以（-6.5±1.2）mm/a的速度下降，但下降速度以0.9 mm/a²的趋势减缓。研究期间内，华北平原的陆地水、地表水和地下水整体分别呈现（-2.0±0.6）、（2.9±0.7）和（-4.8±0.7）mm/a的变化趋势。最后，利用交叉小波谱分析了GRACE滞后于降水的现象。研究结论表明，降水和地下水开采是影响华北平原水储量变化的两大决定性因素。

North China Plain Water Storage Variation Analysis Based on GRACE and Seasonal Influence Considering

Based on the remove-restore method, the GRACE satellite gravity data are used to study the variation of terrestrial water storage from January 2003 to June 2014 in North China Plain. A method for calculating the scale factor considered seasonal influence is proposed to reduce the GRACE post-processing error. The results obtained by the proposed method are compared with those from hydrological model and the precipitation model. The results indicate that serious drought occurred in North China Plain before 2008, and the terrestrial water and surface water decrease at the rate of (-7.9±2.4)mm/a and (-7.3±2.8)mm/a respectively while the groundwater decrease only at the rate of (-0.6±1.4)mm/a. However since 2008, the terrestrial water and surface water show an upward trend of (4.3±1.3)mm/a and (10.9±2.1)mm/a respectively.On the other hand, the over-exploitation of groundwater began to aggravate, and groundwater level showed a downward trend of (-6.5±1.2)mm/a, but the descent rate was reduced at the rate of -0.9 mm/a².During the study period, the terrestrial water, surface water and groundwater storage in North China Plain show a trend of (-2.0±0.6)mm/a, (2.9±0.7)mm/a and (-4.8±0.7)mm/a respectively.Finally, the phenomenon of GRACE lagging behind precipitation is analyzed using cross-wavelet spectrum.Research revealed that the two most crucial factors influencing the water storage variation in North China Plain are precipitation and groundwater exploitation.