Equivalent water height changes over Qinghai-Tibet Plateau determined from GRACE with an independent component analysis approach

Abstract

We estimated the equivalent water height (EWH) over Qinghai-Tibet Plateau (QTP) from time-variable gravity field models derived from the Gravity Recovery and Climate Experiment (GRACE) data released by CSR, JPL, GFZ, and GRGS. EWHs calculated from CSR, GFZ, JPL, and GRGS models, respectively, were taken as the observed signals, and the corresponding 4 independent source signals of each observed signal were determined by independent component analysis to remove the north-south stripe errors and identify the fourth independent components as meaningful water storage change (WSC) signals. These interesting signals are highly correlated to those predicted by hydrological models such as CPC and GLDAS with the maximum and minimum correlation coefficients of 0.89 and − 0.5, respectively. The result shows that EWHs over QTP wholly have the rising trend with the mean rate of WSC of greater than 0.7 mm/year. The in situ precipitations on 140 meteorological stations are also analyzed to verify the water storage changes determined from GRACE data. The results indicate that precipitation is one important water source to replenish the groundwater in QTP.