GOCE: Data Archiving and Processing Facility (DAPC) Graz

The satellite gravity mission GOCE (Gravity Field and Steady-State Ocean Circulation Explorer), the first Core mission of ESA’s Living Planet Programme, strives for a high-accuracy, high-resolution model of the Earth’s gravity field. The precise knowledge of the Earth’s gravity field will make an impact on many branches of Earth sciences. It will be applied to improve the modelling of the Earth’s interior, of geodynamic processes related to the lithosphere, and of the global ocean circulation, which plays a crucial role in climate regulation. In geodesy, it will provide a high-accuracy global height reference system, and it will improve the orbit prediction of satellites. The computation of an Earth‘s gravity field model, expressed in terms of about 70,000 parameters, from several 100 million observations is a laborious numerical task, and requires sophisticated processing algorithms. The scientific objective of the GOCE DAPC project was the design of an operational software system for the GOCE data processing and its installation as a first prototype, which is complemented by a data base design and archiving system concept for data retrieval. Two computation strategies have been followed: Applying parallel processing strategies on a PC cluster, the large normal equation systems are solved rigorously. Additionally, a fast, iterative solver has been implemented, for the purpose of quality assessment of the GOCE sensor system in the course of the mission.