Measuring sea surface height variations is essential for climate change monitoring. About two thirds of the Earth surface is covered by water. Satellite altimetry is the only technique that is able to provide absolute and precise sea surface height measurements globally and with homogeneous data distribution. The heights are given with respect to a geometric reference frame implicitly defined by the orbits of the altimeter satellites (i.e. ITRF). The observations are equally distributed in time and space and provide consistent information on sea level change on different spatial and temporal scales for a time period of about 25 years.
DGFI-TUM administrates complete data holdings of all altimeter missions since 1991 (radar and laser) and maintains an open database for satellite altimeter data and derived high-level products (OpenADB). All altimeter missions are carefully harmonized and cross-calibrated on a regular basis. The derived global multi-mission dataset is used for various ocean applications, among them the trend estimation of global mean sea level (GMSL) and regional sea levels, dynamic ocean topography, geostrophic surface currents and empirical ocean tides. A specific focus of DGFI-TUM's research in satellite altimetry is put on the observation of the sea surface in challenging environments, such as polar and coastal waters. Satellite altimetry was originally designed for open ocean applications but it can also be used for water level monitoring of inland waters, i.e. lakes, reservoirs, rivers, and wetlands. In order to reach sufficient accuracy, special data treatment is mandatory to account for land contamination of the radar echoes (waveforms).