GFZ German research centre for geo sciences

Section 1.1: Space Geodetic Techniques

[Translate to English:] GNSS-Infrastruktur und Analyse

GNSS Infrastructure and Analysis

High-accurate satellite navigation is the most important observation technique in geodesy und surveying. Providing observations and derived products for the satellite navigation systems GPS, GLONASS, Galileo, BeiDou, and QZSS is our main task.

[Translate to English:] GNSS-Antenne

Real-Time GNSS

In order to use satellite navigation in applications such as surveying or early warning systems for earthquakes or tsunamis, the solutions must not only be highly accurate, reliable, and continuous, but also be available with a delay of not more than a few seconds. To this end, we provide GNSS observations and products for different satellite constellations in real-time.

[Translate to English:] VLBI-Antenne

Geodetic and astrometric VLBI

Very Long Baseline Interferometry (VLBI) is a highly accurate method, used since the 1970s in astrophysics as well as in geodesy and has delivered groundbreaking scientific discoveries. This technique allows for example to measure global distances with millimeter accuracy, thus, the VLBI contributes significantly to the global terrestrial reference frame (ITRF), and is the only one of the space geodetic techniques to give the reference to the sky fixed reference frame and all Earth orientation parameters (polar motion, universal time, precession / nutation).

GNSS Tomography

GNSS Meteorology

The observations of geodetic GNSS ground stations can be used to measure the water vapor content above the stations. GNSS data from geodetic receivers are operationally analysed at GFZ and the products are used to improve regional and global weather forecasts and for climate studies. In the last two decades, ground-based GNSS technique for atmospheric sounding (GNSS meteorology) have developed rapidly and are now a standard method for atmospheric remote sensing.

GNSS radiooccultation

GNSS Radio Occultation

GNSS radio occultation measurements from low Earth orbiting satellites can be used to derive globally distributed vertical profiles of atmospheric parameters, as, e.g., temperature, water vapor or electron density. This technique is currently operationally applied at GFZ using the data from GRACE, TerraSAR-X and TanDEM-X. The analysis results are provided for the provision of global weather forecasts and used for climate studies.

GNSS reflectometry

GNSS Reflectometry

GNSS signals are reflected by water, ice and land surfaces. This feature is used to derive properties of the reflecting surface, as, e.g., altimetric height, roughness, soil moisture or snow properties. This new and innovative remote sensing technique is versatilely applied and improved at GFZ. For this purpose experiments with GNSS receivers on the Earth surface and aboard airships, aircrafts and satellites are planned and carried out.

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