National and international cooperations

Various branches of the German Aerospace Center (DLR) contribute to the success of the GRACE missions. In addition to the German Space Agency in Bonn (GRACE and GRACE-C mission management), these institutes include in particular the Raw Data Centre in Neustrelitz (telemetry data), the German Space Operations Centre (GSOC) in Oberpfaffenhofen (mission operations), the Institute of Satellite Geodesy and Inertial Sensing in Hanover (sensor data analysis) and the German Remote Sensing Data Centre in Oberpfaffenhofen (complementary remote sensing data).

The evaluation of the GRACE data is coordinated in the German-American Science Data System (SDS). In addition to GFZ and DLR, the American partners are NASA's Jet Propulsion Laboratory (Pasadena, California) and Goddard Space Flight Center (Greenbelt, Maryland) as well as the Center for Space Research at the University of Austin (Texas). From the archiving of Level-0 sensor data (telemetry data), the processing of the various Level-1 instrument data to global Level-2 gravity field models, all the processing steps required for the success of the mission are carried out within the SDS in close coordination between the partners.

Within the Helmholtz Association of German research centers, the GFZ cooperates with the GEOMAR Helmholtz Centre for Ocean Research (Kiel) and the Alfred Wegner Institute for Polar and Marine Research (Bremerhaven) especially for the calculation of user-friendly data products on ice mass changes in Greenland and Antarctica. Researchers at the Technische Universität Dresden also contribute to the Level-3 data provided via GFZ's GravIS portal (Gravity Information Service). Close links also exist with research groups at the t3://page?uid=27Technical University of Munich (realization of the future gravity field missions NGGM/MAGIC), the University of Bonn (geoscientific applications), and the HafenCity University Hamburg (climate research). Numerous ties exist to Lower Saxony, where critically important research is being performed at the Leibniz University of Hanover (geodetic evaluation methods for Level 1 data), the Max Planck Institute for Gravitational Physics in Hanover (sensor development), the Physikalisch-Technische Bundesanstalt in Braunschweig (gravity field determination with clocks), the Centre for Applied Space Technology and Microgravity in Bremen (satellite simulations) and the local DLR institutes towards the preparation of gravity field satellite missions of the next generation and beyond.

Other long-standing links within Germany exist regarding the utilisation of gravity field data for hydrological applications. These include in particular the Goethe University Frankfurt (hydrological modelling), the University of Stuttgart (stochastic modelling) and the German Geodetic Research Institute at the Technical University of Munich (satellite altimetry). There is also close cooperation with the Federal Agency for Cartography and Geodesy in order to make terrestrial gravity observations useful for monitoring regional changes in terrestrial water storge. Through the participation of GFZ researchers in the Terrestrial Observation Panel for ClimateIn contrast to weather, which refers to daily or very short-term events, climate refers to an average condition in the atmosphere over a longer period of 30 to 40 years. All processes such as average temperature, precipitation, wind direction, wind s... (TOPC) of the Global ClimateIn contrast to weather, which refers to daily or very short-term events, climate refers to an average condition in the atmosphere over a longer period of 30 to 40 years. All processes such as average temperature, precipitation, wind direction, wind s... Observing System (GCOS) led by the World Meteorological Organization (WMO), contributions of satellite gravimetry to essential climate variables (especially terrestrial water storage and groundwater) are provided. The GFZ also regularly contributes to the Annual State of Water Resources Report of the World Meteorological Organization (WMO) with data and analyses on changes in terrestrial water storage based on gravimetric observations.

At the European level, the GFZ maintains since the time of its foundation regular and intensive exchanges with the Groupe de Recherche de Géodésie Spatiale (GRGS) of the French space agency Centre national d'études spatiales (CNES) on a wide range of theoretical and practical problems in gravity field determination with satellite methods (Level-1 and Level-2 data). Close ties also exist with the University of Berne in Switzerland, which is home to the International Association of Geodesy (IAG) combination service for time-variable gravity field models (Level-2 data). On problems related to stochastic modelling within the calculation of GRACE gravity fields, there are regular exchanges with researchers at the Graz University of Technology. In the numerical modelling of the Glacial Isostatic Adjustment (GIA) phenomenon, which is of central importance for geophysical signal separation, we cooperate in particular with the Charles University in Prague and the Geodetic Survey in Sweden (Lantmäteriet in Gävle). The GFZ has been working closely with the Polish Space Research Centre in Warsaw for many years on the interpretation and prediction of Earth orientation changes by using also the GRACE observation data. A variety of smaller, additional projects with numerous other partners from Germany, the Netherlands, Spain or Turkey make the GFZ a central partner in Earth system research with the GRACE satellite missions.

Text: Dr. Henryk Dobslaw, GFZ