Section 1.1: Space Geodetic Techniques

Satellite navigation nowadays is integral part of everydays life just as mobile telecommunication or internet. But the precise analysis of the satellite signals not only provides precise information on positions and velocities, which can be used for navigation. Already in the 80s the potential of the globally and continuously available navigation satellite signals for various geoscientific applications was recognized. The vision of our work in section 1.1 is to understand the GPS, GLONASS, BeiDou and future Galileo navigation satellite systems as powerful tools for Geosciences and to optimally exploit their potential for the observation of the complex System Earth. The - likewise most complex - diversity of our scientific activities ranges from precise monitoring of continental plates movement with sub-mm/year accuracy, over regional and global atmospheric and ionospheric sounding, up to the monitoring of water and ice surfaces and investigations related to future satellite-based Tsunami early warning systems. In addition, we also adapt, together with partners from industry, navigation satellite receivers for geoscientific applications.

Nowadays car navigation without GPS is unimaginable. But GPS, and the European navigation satellite system Galileo - currently being constructed - can do much more than support navigation applications. The scientific work of GFZ section 1.1 is focussed to geophysical applications of Global Navigation Satellite Systems (GNSS). We use precise geodetic receivers to record the movement of lithospheric plates to an accuracy of sub-millimeters per year or to investigate geophysical processes during an earthquake. We also measure vertical land movements resulting from changes of the weight of covering snow or water, or the land raising as a relict of the last ice age. We also exploit the propagation properties of the GNSS signals. On their way from the GNSS satellites (at around 20000 km above Earth's surface) to the receivers on the ground, the signals are affected by the atmosphere but also ionosphere. This feature is an error source for precise navigation and positioning but gives information about the atmosphere/ionophere, as humidity, temperature or electron density. We apply this principle with radio occultation measurements from the GFZ satellite CHAMP (2000-2010) and several international missions, as, e.g., GRACE-A, TerraSAR-X, TanDEM-X, Metop, or COSMIC. Hereby we analyse the GPS signals that, e.g., CHAMP records, when it "sees" a GPS satellites setting behind the horizon. The main result of such measurements are globally distributed and very precise vertical profiles of temperature and water vapor in the atmosphere, which are continuously used to improve numerical weather forecasts or to identify climatological variations of the Earth's atmosphere.

The frequency of GNSS radio signals is in L-band (1.2 and 1.5 GHz), and therefore the signals are reflected by water and ice surfaces. We investigate how these reflected or scattered radio waves can be used scientifically. One example is the use for precise height determination of water surfaces. One advanced application is the mapping of glacier surfaces or sea- and shelf-ice in Greenland and Antarctica. Another application is the derivation of wind speed and direction of the reflecting surface, e.g., the open ocean. Within the German-Indonesian Tsunami Early Warning System (GITEWS), we investigated the potential satellite based application of GNSS reflectiometry for future generation Tsunami warning systems. For this purpose we study the application of reflectometry aboard small satellites, which potentially can be used to build cost-effective multi-satellite constellations with sufficient density of measurements for early warning systems.

Section Head

Profile photo of  Prof. Dr. Harald Schuh

Prof. Dr. Harald Schuh
Space Geodetic Techniques

Telegrafenberg
Building A 17, room 10.02
14473 Potsdam
tel. +49 331 288-1100

Deputy Section Head

Profile photo of  Prof. Dr. Jens Wickert

Prof. Dr. Jens Wickert
Space Geodetic Techniques

Telegrafenberg
Building A 17, room 20.03
14473 Potsdam
tel. +49 331 288-1758

Assistance

Ms. Kirstin Winkler
Assistance of Space Geodetic Techniques

Telegrafenberg
Building A 17, room 10.24
14473 Potsdam
tel. +49 331 288-1110