Hydrological model LSDM for operational Earth rotation and gravity field variations

Water mass redistributions within the global hydrological cycle are one of the main endogenous geophysical processes causing Earth rotation and gravity field variations on seasonal to inter-annual time scales.To simulate hydrospheric induced Earth orientation parameters and gravity field coefficients the complex system of global water mass transports has to be modelled.Operational data of atmospheric and oceanic water mass redistributions are widely used for near real-time simulations of hydrospheric Earth rotation excitation and gravity field representations.They are also essential for de-aliasing purposes of the GRACE (Gravity Recovery Climate Experiment) gravity products.In addition to atmosphere and ocean, seasonal and inter-annual variations are caused by continental water mass redistributions.In order to account for the terrestrial hydrology processes as well and to close the global water cycle, continental water mass storage fields and fluxes are needed in the same operational manner as for atmosphere and ocean.The operational LSDM (Hydrological Land Surface Discharge Model), presented here, has been built on the basis of the existing SLS (Simplified Land surface Scheme) and HDM (Hydrological Discharge Model).These two sub-models have been recoded, extended, and combined to enable a consistent operational simulation of continental water mass redistributions in the focus of a global hydrosphere simulation system.The processing system of LSDM, including the new land surface module LSXM (Land Surface eXtended Model), the revised discharge module HDXM (Hydrological Discharge eXtended Model), and optimized mass conservative remapping algorithms, has been adjusted to work closely with ECMWF (European Centre for Medium-Range Weather Forecasts) atmospheric forcing fields.Alternative atmospheric forcing from other models like NCEP (National Centers for Environmental Prediction) or the climate model ECHAM can be easily implemented in the same fashion.LSDM routinely provides