Terrestrial water storage data based on the generalized three-cornered hat fusion method

We deduct 2004-2009 means from the three GRACE terrestrial water storage (TWS) Mascon products (CSR, JPL and GSFC) to ensure that they have the same reference period. To eliminate the discrepancies induced by the different data and improve the reliability of the results, we estimate the relative uncertainties of the GRACE TWS data using the generalized three-cornered hat method (GTCH), and then fuse them according to their uncertainties using a least squares method.