INTERNATIONAL GEOID SERVICE REPORT (1999 – 2001)

Since the IAG/IUGG General Assembly held in Birmingham, IGeS has developed several activities, both on the international and the Italian side.

One of the main tasks of IGeS was to promote and to organize schools on geoid determination, focussed on theoretical and practical aspects.

On February 2000, a geoid school was held in Johor Bahru (Malaysia) in cooperation with the Department of Survey and Mapping Malaysia (DSMM), acting as local organiser.

This was the fourth international school organised by IGeS in the last six years. The general purpose of this school was to prepare new graduate students, young scientists or employees of national agencies and services or industry staff, to use and, when necessary, to compute gravimetric geoids for the many scientific and technical applications.

The topics discussed during the five lectures were: a general introduction to physical geodesy with special emphasis on geoid computation and collocation theory; the computation and use of high degree and ultra-high degree geopotential models; the geoid computation using Stokes’ integral; terrain effetcs in geoid estimation; FFT techniques in geodesy.

Forty-one students coming from Australia, Chile, China, Ethiopia, France, Hong Kong, Indonesia, Malaysia, Nepal, Singapore, Sweden, Republic of Maldives and USA attended the school. Lecture Notes and IGeS software have been provided as well as numerical exercises which have been made available to the students.

A further geoid school was planned on January 2001 in Cairo, Egypt. However, due to organisational problems, this school wasn’t held and was rescheduled for February 2002. A geoid school in the Unites States is also planned on December 2001 in San Francisco.

Furthermore, IGeS was actively involved in a relevant project for geoid determination in South America.

This project was carried out in strict cooperation with NIMA and the Escola Politécnica, Universitade de São Paulo and led to two new estimates of the quasi-geoid over an area covering the whole South America. These results were presented during the South America Geoid 2000 Workshop held at the Escola Politécnica, Universidade de São Paulo, from May 17 to 19, 2000. This meeting was organized by IGeS (International Geoid Service), SCGGSA (Sub-Commission for Gravity and Geoid in South America), CDC (Committee for Developing Countries) and it was also supported by IAPSO (International Association of the Physical Science of the Ocean). The workshop aimed at encouraging cooperation in data delivery among South American nations in the framework of the SCGGSA activities and also at promoting national and regional geoid estimates in South America. Furthermore, cooperation between oceanographers and geodesists for the computation of the geoid in coastal areas was encouraged.

Seventeen participants attended the workshop and the South America nations involved were Argentina, Brazil, Chile, Ecuador, Paraguay and Uruguay. The new quasi-geoid solutions were also presented at the IAG Symposium on Vertical Reference Systems (VeReS), Cartagena, (February 2001) and during the last EGS Assembly in Nice (March, 2001).

Future projects will involve IGeS in geoid estimation activities in Antarctica and in South Africa: a preliminary data analysis on gravity data in an area of Antarctica has been presented at the Nice EGS Assembly in the G7 Session on “Regional and local gravity field approximation”.

IGeS web has been also updated during these two years and contains at present 23 geoid data files and a collection of 11 global geopotential models. In the near future, software on terrain correction and GIS for geoid update will be made freely available through the IGeS web.

Another important activity which started in 1993, namely the publication of the IGeS Bulletin, was continued and improved. The Bulletin number 10 was published on May 2000 and the next issue is going to be published within May 2001: starting from the tenth issue, the Bulletin became a reviewed scientific journal. The next important change will start with the future issues that will be published almost entirely on CD .

IGeS also actively participated, together with BGI, NIMA, ICET and GFZ, in the creation of a new IAG service named International Gravity Field Service (IGFS). IGFS has been proposed as a unified structure aiming at collecting, validating and distributing data and software for the purpose of determining, with various degrees of accuracy and resolution, the gravity potential of the Earth, or any of its functional, and the surface of the Earth.

In Italy, IGeS worked at estimating and refining the Italian geoid and is cooperating with the Italian Space Agency (ASI), the Istituto Geografico Militare (IGM) and the Agenzia del Territorio (Italian National Cadastre).

Also in this context, IGeS has organised schools on theory and practice for geoid computation. They were held at the IGeS Main Centre (DIIAR, Politecnico di Milano) on February 2000, at IGM in Florence on October 2000 and in Rome at the Agenzia del Territorio on January 2001.

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