Three overarching research topics are highly cross-related to the research areas Reference Systems and Satellite Altimetry for which they provide important foundations.
The Atmosphere affects all measurement techniques of space geodesy. On the one hand atmospheric effects such as refraction or signal delay are a major source of errors that needs to be reduced. Thus the optimization of respective corrections and models means an important research challenge. On the other hand the observation data of various geodetic measurement techniques that are influenced by the atmosphere in different ways provide valuable information on state and dynamics of the atmosphere. These are of great interest for other disciplines, such as meteorology or navigation. In particular the DGFI-TUM has been building up strong experience in the modelling and prediction of global and regional physical structures of the Earth's ionosphere (4D electron content, space weather) from the joint analysis of space geodetic observations.
The precise knowledge of the Earth's gravity field is vital for various applications in geodesy, such as the realization and unification of height systems and the determination of highly precise satellite orbits. The latter are a prerequisite for the computation of accurate reference frames or reliable estimates of water heights from satellite altimetry. Furthermore the geoid provides the reference surface for ocean circulation. Temporal changes of the gravity field carry information about mass transports in the Earth system and are of great interest, for example, for the investigation of dynamic processes in the Earth's interior or within the hydrosphere. The DGFI-TUM primarily focuses on theoretical and practical aspects of regional gravity field determination. The goal is the creation of highly resolved and accurate potential fields for delimited areas through combination of various available data sets, e.g. satellite gravity field information, satellite altimetry, or terrestrial and airborne gravity data. The focus of the work is on the computation of high-resolution potential information in ocean areas, the unification of height systems, and the determination of the temporally and spatially variable difference between geoid and sea surface (Dynamic Ocean Topography) as basis for the derivation of geostrophic ocean currents.
A fundamental prerequisite for any meaningful combination of different data sets is the definition and application of common standards and conventions in order to assure highest consistency of parameters and products. In the frame of the Global Geodetic Observing System (GGOS) the DGFI-TUM manages the GGOS Bureau of Products and Standards (BPS) that is operated jointly with partners of the FGS.