Basin-scale water-balance estimates of terrestrial water storage variations from ECMWF operational forecast analysis

In recent publications, a new basin-scale dataset of monthly variations in terrestrial water storage (BSWB) was derived for the ERA40 time period (1958-2002) using an atmospheric-terrestrial water-balance approach (Seneviratne et al., 2004; Hirschi et al., 2006). Here, we test the feasibility of using ECMWF operational forecast analyses available for the recent time period in near real time instead of reanalysis data for the derivation of these estimates. Our results suggest that the moisture flux convergence from the ECMWF operational forecast analysis is generally consistent with ERA40 in the investigated regions, including 35 mid-latitude river basins and domains. For ten domains with recent streamflow measurements, water-balance estimates of monthly terrestrial water storage variations derived using the ECMWF operational forecast data are compared with estimates from the Gravity Recovery and Climate Experiment (GRACE). In general the atmospheric-terrestrial water-balance estimates show more geographical detail than the analyzed standard resolution GRACE products.