Tailored regional gravity field models for mass distribution and mass transport phenomena in the Earth system.

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The main task of this proposal is the rigorous mathematical treatment of a localized modelling of geophysical fields, the development of improved techniques to derive the space-time structure of the gravity field, the implementation of these improvements in the ITG Gravity field Recovery Software package to determine precise global gravity field models with regional focus from the original level-1 observations and, most important for the various proposals of this SPP1257, the assimilation of the gravity field products into oceanographic, hydrologic, glaciological and geophysical models referred to selected regions. Various mass transport phenomena in the Earth system are regionally bounded and the inhomogeneous mass distributions are reflected in geographically varying gravity field functionals. These functionals cause signals with varying strength and can be detected with high precision by the innovative sensors of the new gravity and altimetric satellites. Therefore, regional space-time structures of the gravity field shall be derived by tailored modelling and analysis techniques based on the line-of-sight observations of the GRACE twin-satellites as well as on the observational functionals of the gravity gradiometry mission GOCE. The regional gravity field structures modelled by space-time localizing base functions and consistently embedded into a datum referenced mean global solution shall be assimilated with the corresponding oceanographic, hydrologic, glaciologic and geophysical models provided by the various projects of SPP 1257. Alternative observables as derived from the altimetric satellites as well as terrestrial and airborne gravity field measurements shall be integrated consistently into the assimilation procedure. From the mathematical point of view the discrepancy of a rigorous localisation with the intrinsic non-locality of solutions of the Laplace equation for the gravitational potential shall be investigated. Besides these basic mathematical problems of a regional modelling of the gravity field with space-localising base functions algorithms shall be developed to find statistically justified procedures to model the mass distribution and the various mass transport phenomena in the Earth system.