摘要
利用GRACE重力卫星数据反演得到陆地水储量变化,可监测大尺度区域水储量变化,但该数据空间分辨率低,在中小尺度上很难应用。基于GRACE陆地水储量变化和其他水文要素的关系,提出一种基于GRACE陆地水储量变化的统计降尺度方法,即将GRACE反演得到的空间分辨率为1°的水储量变化数据降尺度到0.25°,并运用地下水及土壤含水量的变化总量来验证降尺度之后数据的可靠性。结果表明,该统计降尺度方法成功应用于云南中部地区,降尺度后的水储量变化和实测的水储量变化的时间序列在三个验证监测点的相关系数均超过0.82,而相对误差低于5.5%,并利用降尺度的结果分析了2009年7月~2010年6月西南大干旱期间水储量及干旱的时空变化特征,发现统计降尺度方法可有效提高GRACE数据的空间分辨率,但也具有一定的不确定性。
GRACE-derived terrestrial water storage change(TWS)is a powerful tool to monitor water storage dynamic change in large scale regions but it is hard to follow at small scale due to its low spatial resolution.Based on GRACEderived TWS and water balance equation,the statistical empirical regression method was applied to downscale GRACEderived TWS in this study.The GRACE-derived TWS data with 1°spatial resolution are converted into those of 0.25°spatial resolution.The downscaling results are validated using measured TWS calculated from groundwater level and GLDAS soil moisture.This downscaling method is successfully applied in the middle region of Yunnan Province.The results show that the correlation coefficient between the downscaled TWS and measured TWS is higher than 0.82,and the relative error is lower than 5.5%in all three validation areas.Finally,the typical drought event from July 2009 to June 2010 is analyzed based on the above downscaled TWS data.Therefore,the statistical regression downscaling method could effectively improve the spatial resolution of GRACE-derived TWS,but it also has some uncertainties.
引文
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