Monthly land waters solutions by least-squares inversion of GRACE geoid data (2002- 2006)

A least-squares inversion procedure is used to derive the Land Waters (LW) variations at the resolution of ~400 km by combining: (1) monthly GRACE solutions from August 2002 to February 2007 recently made available by GFZ; and (2) a priori information from hydrology models. This approach proves to be an efficient strategy to separate different hydrological components (i.e., continental water storage included snow) from other geophysical phenomena, residual errors and high-frequency noise. Time-series of continental water storage for large drainage basin can be derived from these LW solutions, and proved to be consistent in comparison with sparse in situ measurements of water levels and global hydrology models. A posteriori uncertainties on the estimated LW coefficients and errors from spectrum truncation and leakage can also be computed.