利用高分辨率水文模型提高GRACE卫星的空间分辨率

为克服GRACE卫星数据空间分辨率粗糙的局限性,本文以高空间分辨率的PCR-GLOBWB数据为基础,构建了加权、乘权及误差分配降尺度方法,将GRACE卫星在河北省的水储量变化数据的空间分辨率由0.50°提高至0.05°。结果表明:加权降尺度方法不仅保留了GRACE数据的原始空间分布特征,还刻画了局部细节特征;误差分配降尺度方法结果较为理想,但在格网交界处的信号存在跳跃现象;乘权降尺度方法表现最差,与GRACE存在明显差异。经实测数据验证可知,加权降尺度方法与实测值拟合程度最好,相关系数最高可达0.81。本文为获取河北省高空间分辨率地下水储量数据提供了有效保障。

Improving the spatial resolution of GRACE satellites based on high-resolution hydrological simulations

To overcome the limitation of the coarse spatial resolution of GRACE observations, this study selects PCR-GLOBWB simulations as the reference data with higher resolution. Three kinds of downscaling schemes are employed to improve the resolution of GRACE data in Hebei province from 0.50° to 0.05°, namely add weight downscaling method (AWDM), multiply weight downscaling method (MWDM), and error distribution downscaling method (EDDM), respectively. The results indicate that the AWDM-based scheme can not only preserve the original spatial characteristics of GRACE observations, but also give signals at local areas. Although the EDDM-based scheme can also provide ideal downscaled results, there are obvious jumps with regard to the signals between the junction of different pixels. In contrast, the worst performance is observed in the MWDM-based scheme, which is significantly different from the actual GRACE signals. In-situ groundwater level measurements highlight that the AWDM-based downscaling scheme is superior to other downscaling methods, and can provide reasonable downscaling performance with the correlation up to 0.81. This study provides an effective guarantee for obtaining high spatial resolution groundwater storage data in Hebei province.