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       17-Jul-2014
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Monthly and Weekly EIGEN-GRACE05S Gravity Field Solutions for Monitoring of Mass Variations in the Earth System
Schmidt, R.; Meyer, U.; Dahle, C.; Kusche, J.; Flechtner, F.
GFZ Potsdam

GFZ Potsdam, as part of the Gravity Recovery and Climate Experiment (GRACE) Science Data System (SDS), is responsible for routine generation of monthly gravity field products. Just recently, nearly the complete 5.5 years mission data have been reprocessed based on improved background models and application of the full IERS2003 standards. This new release is called EIGEN-GRACE05S respectively Release 04 (RL04) in the GRACE SDS naming convention. It currently provides 55 monthly gravity field models in terms of spherical harmonics allowing for the resolution of changes in mass anomalies at the Earth’s surface down to about 500 km half-wavelength and smaller. These time series clearly trace, after appropriate filtering of spurious meridional striping, mass variations in the Earth system such as the continental water cycle, the ice mass balance in Greenland and Antarctica, or the post-glacial rebound in Canada and Fennoscandia at such spatial scales with an accuracy of 2-3 cm in terms of equivalent water height. In addition with other geodetic and geophysical data the GRACE-based estimates of changes of surface mass anomalies allow for a quantification of ongoing mass transfers, thus providing a novel substantial input to the numerical modelling of geophysical and climatologically driven phenomena (as e.g. global hydrology).

In order to increase the temporal resolution of the standard monthly products weekly solutions by different concepts ranging from moving averages, pure subset solutions to stochastic or functional modelling are currently under investigation at GFZ Potsdam. These higher resolution time series are analysed and compared to the standard monthly solutions, independent data sets (e.g. SLR and GPS-based) and geophysical/climatological models (in particular global hydrology) showing the capability of GRACE, depending on the weekly ground track pattern and instrument data availability, to monitor large scale mass variations on such smaller temporal scales.

The presentation will show typical results obtained with the standard EIGEN-GRACE05S data as well as with the experimental weekly gravity model series, with a focus on global hydrology.

 

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