Topics

Section 1.1 is involved in research and development activities in the following topics

GNSS Atmosphere Sounding
Ground-based GPS data from a global and from regional networks are analyzed in near-real time. Resulting data products (zenith and slant total delay, integrated water vapor) are provided for the operational assimilation to regional weather models and for several scientific investigations. GFZ also supports temporary atmospheric measuring campaigns (e.g. CSIP: 2006; COPS:2007; WMO-LUAMI:2008) by the installation, operation and data analysis of GPS ground stations. GPS slant data from the German network (350 stations in analysis of Sepot. 2009) are used to reconstruct 3D water vapor distributions.

A second pillar of GFZ expertise in atmospheric sounding is the satellite based GPS radio occultation (RO) technique for precise vertical atmospheric sounding on a global scale. The GFZ spectrum here covers activities related to data processing (CHAMP, GRACE, TerraSAR-X, Metop, COSMIC), but also the application of the RO data for various scientific investigations at GFZ. An example for the data processing is the provision of GPS RO data in near-real time for the continuous assimilation to improve weather forecasts at different national and international weather centers. Scientific investigations focus to the exploitation of the RO data for climatological investigations of tropopause and gravity wave characteristics, but also to detailed analysis of the occurrence of ionospheric irregularities. Additional investigations are related to the design of new satellite missions using GPS remote sensing techniques.

The main part of the GFZ activities in GNSS atmosphere sounding is performed within the Helmholtz Research field "Earth and Environment", programme "Atmosphere and Climate" in close cooperation with FZ Karlsruhe and FZ Jülich.

GNSS Geodynamics
Links to the projects under this topic:
- SAGA
- IPOC
- JOGA
- LENA

GNSS Reflectometry
GPS Scatterometry and Reflectometry are regarded as innovative remote sensing techniques in the field of altimetry, oceanography and glaciography. The high reflectivity of GPS signals in the frequency range of L-Band (1,2 and 1,6 GHz) on water as well as iced and snow covered surfaces partly compensates for the low signal intensity and allows the detection of reflected signal components. Part of the GFZ activities in GNSS reflectometry is performed within the GITWES research project. It covers a simulation study for a future satellite based tsunami warning systems using GPS Scatterometry and Reflectometry and activities related to the development of appropriate GPS receivers.

GNSS data analysis und software development
This research area includes activities within the IGS (International GNSS Service), development and improvement of GNSS data analysis software and contributions to the European navigation satellite system Galileo. GFZ contributes to IGS with currently 23 globally distributed ground stations and by hosting an operational Data and Analysis Centre (AC). GFZ is also involved in the generation and maintenance of the International Reference Frame (ITRF) and to the provision of precise satellite orbits, clocks and Earth rotation parameters. From 2003 to 2007, the Analysis Coordination (ACC) was the task of GFZ and the official combined satellite orbit and clock products were generated here. GFZ has been developing GNSS analysis software for decades and is maintaining the software according to the latest standards and developments. GFZ is also very active in developing new algorithms in order to improve the quality of the IGS products and to enhance the capability of GNSS data processing (see Highlights). Since 2007, GFZ has been developing its GNSS real-time software package, EPOS-RT. The software is designed not only to run in network mode which is now used for geohazard monitoring (earthquake, tsunami, volcano, landslide), but also to be able to estimate orbit and clock corrections to provide services to users with single-frequency receivers in precise point positioning mode (IGS Real-Time Pilot Project). The above-mentioned functions can be demonstrated now and further improvement on the robustness and accuracy of the software is in progress. The Galileo Geodetic Service Provider (GGSP) Prototype was developed to support the In-Orbit-Validation for the Galileo System in 2011, and will be offered to be part of the final Galileo system.

links to the projects under this topic:
- IGS
- G-SEIS
- GGSP
- GGSP-HAPS