IGGOS

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GGOS is an international geodesy project started in 1999, which aims at a consistent earth model of the geometry and the gravity field and a network of different satellite-based methods of earth observation . The acronym stands for Global Geodetic Observing System ( GGOS ). GGOS has been a component of the International Association for Geodesy since 2007 .

Goal setting

The international and interdisciplinary networking of earth-related data is an increasingly pressing task that has been required for several years due to the increasingly detailed measurement and analysis methods in the geosciences. From a geological point of view, the earth represents a physical system , for the definition of which the classical geometric data ( earth ellipsoid , earth rotation, fixed points , geographic coordinates, terrestrial base quantities) and definitions are no longer sufficient. The expansion to a complex model of the earth's body requires not only the potential fields (magnetic, earth's gravitational field ) but also the temporal dimension ( geodynamics , continental and earth crustal movements, geoseismics ) and the integration of models from hydrography and oceanography as well as the earth's atmosphere (pressure and load models , Currents, more precise reduction of the measurement data) and remote sensing of the earth's surface.

Contributions of geodesy

Since the initiators of the project come from the Higher Geodesy and related areas of the International Association of Geodesy (IAG), their intention will first be presented.

The geodetic research work - see 1st reference - is intended to contribute to the provision of a consistent and precise system of frames of reference , on the one hand as the basis for all geographic information systems and on the other hand as the metrological basis for the processes of global change. The geodetic contribution to the recording and research of the " System Earth " and the establishment of the "Global Geodetic Observing System" of the IAG is a pivotal point of the [German part of the] research program. The first (now largely fulfilled) sub-task is a high-precision world network and its correlation with geophysical models and the like. a. of plate tectonics and large-scale geodynamics .

As a geometric basis of a GGOS serve the modern space observation techniques such as GNSS (Global Navigation Satellite Systems), in particular the online measurement systems Global Positioning System (GPS), Galileo and GLONASS , the worldwide networks of the DORIS system's and the VLBI -Radioteleskope (Very Long Baseline Interferometry). They are supported by laser technologies SLR and LLR (Satellite and Lunar Laser Ranging), satellite altimetry and satellite-based geoid determination (measurement campaigns by CHAMP and GRACE , ongoing gradiometry with GOCE ). These methods and their interdisciplinary analyzes mean that the Earth system can be observed from space with a previously unattainable accuracy ( mm ... dm ).

Geophysics and geodynamics

Since the end of the 20th century z. B. the plate tectonic continental drift can be determined worldwide with a resolution of about mm / year. In this accuracy range, extremely accurate terrestrial reference systems are required for all earth observations, which are already available in the periodically improved reference framework of the ITRF or Europe-wide of the ETRF . They allow conclusions to be drawn about the constantly changing geometry of the earth's body with regard to earth tides , gravitational field and geoid and about variations in the earth's rotation and increasingly allow insights into the mass shifts and currents in the earth's interior .

Another purpose of IGGOS is the in-depth geoscientific cooperation with physics, mathematics and technology in order to refine the theoretical models of the terrestrial and astronomical interactions and to further develop the measurement methods and adequate databases .

literature

  • R.Rummel, H.Drewes, W.Bosch, H.Hornik: Towards an Integrated Global Geodetic Observing System (IGGOS) . IAG Symposia, Vol.120, Springer, ISBN 3-540-67079-3 , Springer-Verlag, Berlin 2000
  • M. Rothacher, H. Drewes, A. Nothnagel, B. Richter: Integration of space geodetic techniques as the basis for a Global Geodetic-geophysical Observing System (GGOS-D) , Springer 2010