A mass conserving approach for studying the impacts of global water storage changes on gravimetric time series

High precision terrestrial gravity time series as obtained with Superconducting gravimeters are sensitive to local and regional water storage changes. Besides such mass changes in the vicinity of the sensor, global redistribution of water is likely to affect the measurements. To assess the quantity of the changing mass attraction, not only water storage changes of the continental hydrosphere have to be considered, but also the mass exchange and redistribution of masses in the oceans and in the atmosphere. In order to re-assess this effect, we use ECMWF's latest re-analysis ERA Interim together with simulated ocean bottom pressure from OMCT and terrestrially stored water masses from LSDM, which have been both consistently forced by ERA Interim. The mass attraction effect is computed globally from those data sets, and subsequently compared with measured gravity time series at selected stations of the Global Geodynamics Project.