Ground and space based Atmosphere Sounding using GNSS techniques.
The research project ATMO-CHAMP/GRACE is funded within the GEOTECHNOLOGIEN programme of BMBF (2009-2011).
GPS radio occultation with CHAMP
The GPS radio occultation data of the German CHAMP satellite are analysed and globally distributed vertical atmospheric profiles (bending angles, refractivity, temperature, water vapor) are derived and provided for the international user community.
Improvement of precipitation forecast with GPS
COPS-GRID and APRO-GRAVAR
The research projects COPS-GRID ("High-resolution Reanalyses and Impact Studies for Improving Process Understanding and Precipitation Forecast Skill based on the COPS Data Set") followed by APRO-GRAVAR ("Assimilation and Process Studies for selected COPS IOPs using GPS STD and radar radial velocities in the WRF-Var system") were funded within the DFG priority programme "Quantitative precipitation forecast, SPP 1167).
GPS radio occultation with COSMIC
GPS radio occultation data of the U.S.-Taiwan multi satellite constellation COSMIC/FORMOSAT-3 are used to derive (for selected periods) to derive globally distributed vertical atmospheric profiles (bending angles refractivity, temperature, and water vapor). The data products, provided by UCAR, are used for various scientific applications in atmospheric/ionospheric research..
GeoHALO denotes a corporate campaign of different partners in Geoscience to use the German research aircraft (HALO, High Altitude and Long Range Aircraft). The flight campaign was successfully completed in June 2012 over the Mediterranean. The flight covered large areas of the Adriatic, Tyrrhenian and Ionian Sea. Collected GNSS-R data offers the opportunity to advance altimetric methods for airborne ocean remote sensing.
GEROS-ISS is an experiment, foreseen for realization aboard the International Space Station ISS. GEROS-ISS was proposed by a top-class international science team. The work of the team is coordinated by GFZ scientist Dr. Jens Wickert. Involved are scientist and engineers from Germany, Sweden, Spain, U.S., Denmark, and Switzerland.
The realization and maintenance of a Galileo Terrestrial Reference Frame (GTRF) is one of the components contributing to the system performance of Europes Global Navigation Satellite System Galileo. The GTRF shall be compatible with the latest International Terrestrial Reference Frame (ITRF) within a precision level of 3 cm (2 sigma). To achieve this, a Galileo Geodetic Service Provider (GGSP) has been defined by the project already in the early stages of the programme.
Project Galileo High Accuracy Positioning Service Definition (HAPS) in cooperation with ESOC and BKG. The main objective of this study is the identification of potential scenarios for the provision of a Galileo HAPS, its related performance and resulting impact on Galileo Ground and Space Segment.
GFZ is operating a global GNSS station network (currently ~30 stations) since the early 1990s to support scientific research activities like precise satellite clock & orbit determination, radio occultation measurements and crustal dynamics studies.
GNSS Water Vapour Tomography
The GNSS tomography is an attempt to utilize the existing GNSS infrastructure for meteorological applications and to provide temporally and spatially resolved water vapour fields on a national or European scale.
Within the GITEWS project, the development of GORS (GNSS Okkultation Reflektometry Scatterometry) receiver was started. Based on commercial hardware of a JAVAD GNSS two-frequency receiver firmware is adapted to receive reflected signals or those in occultation next to the direct signal. This receiver is used for ground-based or airborne setups. Spaceborne setups are planned.
Disko Bay is situated west of the Greenland coast. Near by the port of Godhavn (69.2717° N; 53.5435° W) a GPS Reflectometry setup was installed. On a cliff about 670 m above sea level, observations over the bay were recorded for several months (in winter season 2008/09). Regular changes of the ocean surface due to ocean tides and sea-ice coverage could be examined with reflection data. This study has been initiated by ESA connected to further measurements of dry snow properties at Dome-C, East Antarctica.
GPS radio occultation with GRACE
The GPS radio occultation data of the German-U.S. GRACE satellites are analysed and globally distributed vertical atmospheric profiles (bending angles, refractivity, temperature, water vapor) are derived and provided for the international user community.
Gravity wave coupling processes
The research project GW-CODE (Gravity wave coupling processes and their decadal variation) is funded within the DFG priority program CAWSES (Climate and Weather of the Sun-Earth System). Within the project global variations of atmosperic wave phenomena are investigated using, among others, satellite data from CHAMP and GRACE. The project is performed in close cooperation with University Leipzig and Forschungszentrum Jülich.
The research project IDEAL-GRACE is funded within the DFG priority program 1257 "Mass Transports and and Mass Distribution in the Earth system. Within the project the influence of atmospheric data and their errors to determination of GRACE based geoid models is investigated. The project is performed in close cooperation with TU Munich, University Hamburg and DLR.
The International GNSS Service (IGS) as a service of the International Association of Geodesy (IAG) provides GNSS data and products with highest quality and that not only to the scientific community. GFZ contributes to this service by operating about 30 globally distributed Multi-GNSS reference stations and hosting one Analysis Centre (AC). With its products namely precise station coordinates, satellite orbits, clock corrections and Earth orientation parameters the AC contributes also to the generation and maintenance of the International Terrestrial Reference Frame (ITRF). From 2003 to 2007, the Analysis Centre Coordination (ACC) was the task of GFZ and the official combined satellite orbit and clock products were generated here.
Currently GFZ contributes to all three IGS product lines: Final, Rapid and Ultra-Rapid. Data of the two full operational Global Satellite Navigation Systems GPS and GLONASS were used for the processing of up to 300 stations. The in-house developed analysis software in its current version EPOS.P8 is used to produce all needed geodetic products as well as some additional ones, e.g. for meteorological applications.
GFZ employees are fellows of several IGS Working Groups, e.g. TIGA (lead), Troposphere and Real-Time.
The observation of the present-day deformation of the Earth's surface with high spatial and temporal resolution makes up a major part of the Integrated Plate Boundary Observatory Chile (IPOC). For this purpose, continuously recording GPS stations were installed in Northern Chile.
The Dead Sea region is a unique natural laboratory and provides an excellent opportunity to study fundamental geodynamic processes on a variety of scales. This will facilitate an understanding of how the interplay of structure and dynamics controls the occurrence and rate of earthquakes. It allows studying the geometry of upper crustal faulting, the mechanics of and asperities in the seismogenic zone, the formation, growth and subsidence of pull-apart basins, as well as how the surface deformation extends to the lower crust and even into the lower lithosphere. Given the scientific foundation provided by the research done until now, it is an ideal and most promising target for further advanced and sophisticated studies aimed at clarifying the relation between fundamental geodynamic processes on one hand and the resulting earthquakes and their relevance for the socio-economic development of this region on the other hand.
One of the key projects in the framework of GEO-DESIRE is the GPS project JOGA (JOrdanian GPS Activities). The primary aim of the GPS observation is the detection of the present day deformation field along the Dead Sea Fault System.
Several small satellite studies (MicroGEM, NanoGEM, NanoX) have been conducted since 2010. The main goal is the realization of a prototype satellite for GNSS reflectometry and radio occultation. Significant benefit is expected due to a future multiple satellite constellation with a high coverage for GNSS Earth Monitoring, that is needed e.g. for tsunami detection.
The LENA project: “Study of the Kinematics and Geodynamics of the Laptev Sea and the Eurasian-North American Plate Boundary”.
Within GITEWS a feasability study was conducted for satellite-based tsunami detection using GNSS-R. Lastest results show that a constellation of multiple low earth orbit satellites would be suitable to detect tsunami waves within 15-25 minutes on a global scale. This estimation implies that the altimetric signal is strong enough.
GPS on Metop (GRAS)
Metop is Europe's first polar-orbiting satellite dedicated to operational meteorology. It represents the European contribution to a new cooperative venture with the United States providing data that will be used to monitor our climate and improve weather forecasting. The satellite was launched in October 2006.
Within the research project NRT-RO (Near Real-Time-Radio Occultation) scientific data analysis software for satellite orbit determination and radio occultation processing is developed which is used for the operational data analysis of the GPS based atmospheric data from CHAMP and GRACE.
The resulting data products are used by several national and international weather centers to improve global weather forecasts since 2006.
NRT-RO was funded by BMBF within the GEOTECHNOLOGIEN research programme 2005-2008. Contact person at GFZ is Dr. Jens Wickert.
Based on OpenSource components an independent single-frequency GPS-R receiver is developed at GFZ.
The L-band carrier of GNSS signals is subjected to permanent frequency shifts due to permanently changing geometry of transmitter and receiver (Doppler effect). This shift affects direct and reflected signals as well. In principal spectral retrievals are not suitable to examine such signals as precise frequencies cannot be derived due to permanent changes.
Nowadays excellent models for GNSS signal propagation are available and allow to derive residuals of the observed signal where only a small frequency shift is left. For reflected signals such residuals are dependent on the height of the reflecting surface (e.g. sea level). Spectral retrieval of residuals allows accumulation of observations. Disturbing roughness effects of the ocean surface can thus be mitigated and ocean altimetry with L-band carrier signals is even possible for moderate sea state. The applicability of reflected GNSS signals for ocean altimetry is thus improved.
Main tasks: (a) design and development of a new series of multi-parameter stations running unattended and autonomously for long periods; (b) development and test of new data communication strategies for high-rate and high-volume data; (c) development of new and automated GPS/GNSS software allowing real-time data analysis and self-detection of events (accuracy: mm to cm).
The Real-Time GNSS Group at GFZ has been working on the development of a real-time precise positioning service since 2007 motivated by the IGS real-time Pilot Project and supported by GSEIS and ZIM projects.
A demonstration system is already in operation.
Go to RT GNSS website.
Western South America is tectonically one of the most active and geodynamically most interesting areas in the world. Aim of the investigation in the framework of the SAGA project is to understand the nature of the present-day deformation (including its temporal and spatial variation) along the Andean subduction zone.
GPS radio occultation with TanDEM-X
The GPS radio occultation data of the German TanDEM-X-satellite are analysed and globally distributed vertical atmospheric profiles (bending angles, refractivity, temperature, water vapor) are derived and provided for the international user community. TanDEM-X was launched June 21, 2010 and forms together with TerraSAR-X a tandem-satellite configuration.
GPS radio occultation with TerraSAR-X
The GPS radio occultation data of the German TerraSAR-X satellite are analysed and globally distributed vertical atmospheric profiles (bending angles, refractivity, temperature, water vapor) are derived and provided in Near-Real Time for the international user community. The data are used by the internationally leading weather centers to improve their global forecasts.
Fahrenberg is a mountain in the Bavarian Alps (47.61° N; 11.32° E). Its summit rises 1625 m above mean sea level. At the foot of the moutain lake Walchensee spreads on an area of about 16 km² with a lake level of about 800 m above mean sea level. The vicinity of lake and mountain offers an ideal location for Reflectometry experiments with the GORS receiver.
The Water-related Information System for the Sustainable Development Of the Mekong Delta (WISDOM) project is a German Vietnamese initiative. Its objective is to build an information system for the Mekong Delta that supports and assists planners and authorities for an optimized and integrated resource management. The system will comprise hydrologic, hydraulic, ecologic and sociologic data. One of WISDOM’s tasks is to test the usability of GNSS-R for water level monitoring of the Mekong Delta. In February 2012, a first measurement campaign in Can Tho City (9.99°N, 105.74°E) was successfully conducted.
In collaboration with DLR and Zeppelin Luftschifftechnik (ZLT) experiments are conducted for Zeppelin-based Occultation, Interferometry and Scatterometry (ZOIS) measurements. Flight campaigns were successfully completed over Lake Constance in October 2010 and September 2012 starting from Friedrichshafen close-by. The Zeppelin airship has an excellent manoeuvrability even at small flight speeds (<100km/h). Due to the manoeuvrability the airship can easily pilot height anomalies on the rather small lake surface. These experiments allow important altimetric studies for following flight experiments over the ocean.