International cooperation and technology transfer

Fras, Mojca Kosmatin

Bibliographic data

Monograph

Persistent identifier:: 856490555

Author:: Fras, Mojca Kosmatin

Title:: International cooperation and technology transfer

Sub title:: Ljubljana, Slovenia, February 2 - 5, 2000 : proceedings of the workshop

Scope:: VI, 163 Seiten

Year of publication:: 2000

Place of publication:: London

Publisher of the original:: RICS Books

Identifier (digital):: 856490555

Illustration:: Illustrationen, Diagramme

Language:: English

Usage licence:: Attribution 4.0 International (CC BY 4.0)

Publisher of the digital copy:: Technische Informationsbibliothek Hannover

Place of publication of the digital copy:: Hannover

Year of publication of the original:: 2016

Document type:: Monograph

Collection:: Earth sciences

Chapter

Title:: APPLICATION OF THE SATELLITE POSITIONING SYSTEMS IN GEODETIC AND GEODYNAMIC PROGRAMMES OF THE CEI WGST SECTION C "GEODESY". Janusz Sledzinski

Document type:: Monograph

Structure type:: Chapter

143 brought about a new philosophy of using permanent GPS observations for geodesy and geodynamics. The great importance of permanent stations for practical geodetic works in every country and for research has been fully recognized in the research programmes of the Central European Initiative (CE1). It is also worth mentioning that at the Conference of the National Representatives of all the countries participating in the CEI Section C cooperation held in Warsaw, 24-25 March 1995, a resolution was adopted on the organisation of permanent stations in CEI countries. Below you find the original version of this resolution: The CEI Section C "Geodesy" recognising the important role of permanent GPS stations for * the maintenance of the ITRF, * both geodetic and geodynamic practical works and research activities, and * the contribution to orbit improvement and permanent monitoring of the Earth rotation and the investigations of the ionospheric effects recommends that each CEI country make efforts to establish at least one permanent station on its territory and requests that all national institutions or agencies responsible for geodetic works and research activities support such action with indispensable financial and any other assistance. Currently permanent GPS observations (stations) are mainly used for the following purposes: • Determination, accuracy improvement and maintenance of the ITRF (International/IERS Terrestrial Reference Frame). These tasks are carried out nowadays by two global services: IGS (International GPS Service for Geodynamics), whose performance is based on a network of permanent GPS stations, and IERS (International Earth Rotation Service), which uses GPS measurements as complementary to observations made by other satellite and space techniques, mainly by Satellite Laser Ranging (SLR) and by Very Long Baseline Interferometry (VLBI). The most important products offered by these services include precise orbits of the GPS satellites, precise positions of permanent stations (and their velocity vectors) and geodynamic parameters of the Earth rotation; they also provide us with clock corrections of GPS satellites and tracking stations as well as with information on the ionosphere and troposphere. In Europe the global network is realised by a continental network that is being established by EUREF (European Reference Frame) campaigns. This network constitutes a precisely defined part of ITRF known as European Terrestrial Reference Frame (ETRF). Recently a new category of EUREF points has been introduced, and these are permanently working stations. • Establishment of reference control networks (stations) for the connection of the national geodetic frames and newly created national active positioning and navigation systems. Points of the EUREF frame and permanently working satellite stations that belong to the IGS and IERS services constitute the basic international (global and regional) frame in Europe to which all national satellite control networks are connected. The national satellite control networks are therefore established as a densification of the EUREF frames and IGS/IERS frames. National active positioning and navigation systems based on permanent reference stations operating in some countries are known as so-called Precise Active Positioning System and Standard Active Positioning System. A growing demand for active systems for land, marine and air navigation has been expressed by public services such as aviation, navy, transport, communication, police, fire department, health and other emergency services. This demand is satisfied by the satellite services of DGPS (Differential Global Positioning System) performing their activity in many countries and providing position of moving objects in real time. • Establishment of points (stations) for geodynamic research and connection of focal geodynamic networks. The new philosophy of geodynamic research consists in analysing permanent precise GPS observations that are performed at geodynamic points (in observatories). This helps to detect geodynamic effects, including the periodical ones, which occur with various amplitudes and various frequencies (with different periods). Today analysis of changes in the velocity vectors of permanent stations constitutes the basis for the most valuable global and regional geodynamic research. A network established recently in Japan can serve as an example of this kind of geodynamic network. The Japanese network consisting of 900 permanently operating stations, monitors all the short-term changes in the position and provides data for geodynamic interpretation and predictions as concerns any possible occurrence of an earthquake. 5. NEW ROLE OF SATELLITE PERMANENT GPS STATIONS In the considerations presented below we shall take into account only these aspects of geodynamic research that refer to analyses of the changes of point positions. The application of permanent GPS observations in determining and improving the accuracy of the global dynamic parameters and in permanent monitoring of the Earth rotation constitutes a separate set of problems which require a separate discussion. By the time the satellite technology was introduced, geodynamic research had been based mainly on the analysis of stability of special points of geodetic triangulation and trilateration networks measured by means of classical measurement techniques, including, above all, linear (distancemeter) measurements, precise angular measurements, precise levelling measurements and gravimetric surveys. The frequency of the measurements of such networks depended mainly on the expected displacement values and the accuracy of the measurement techniques. In many cases determination of slight displacements was difficult due to the'application of insufficiently accurate observation techniques. In fact the same philosophy was used in the analysis of the determined displacements of points of the local and regional networks as well as in research of a global nature while analysing movements of continents or tectonic plates. Analysis of stability in the position of points of a geodynamic network was often conducted separately for horizontal (triangulation, trilateration) networks and for vertical ones: "horizontal" and "vertical" displacements were determined.

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