Report Of IAG Section IV

-GENERAL THEORY AND METHODOLOGY-

ON THE ACTIVITIES BETWEEN 1999 AND 2001

Bernhard Heck, Section President
 University of Karlsruhe
 Geodetic Institute
 Englerstrasse 7
 D-76128 Karlsruhe
 Germany

The structure of Section IV in the period 1999 - 2003 is essentially the same as in the former four-year period. It consists of the Special Commission

  SC1 : Mathematical and Physical Foundations of Geodesy
    Chair: P. Holota

covering broader and long-term items of geodetic theory and methodology in its sub-commissions and working groups, and of the five Special Study Groups

  SSG 4.187 : Wavelets in Geodesy and Geodynamics
    Chair: W. Keller

  SSG 4.188: Mass Density from Joint Inverse Gravity Modelling
    Chair: G. Strykowski

  SSG 4.189: Dynamic Theories of Deformation and Gravity Fields
    Chair: D. Wolf

  SSG 4.190: Non-Probabilistic Assessment in Geodetic Data Analysis
    Chair: H. Kutterer

  SSG 4.191: Theory of Fundamental Height Systems
    Chair: C. Jekeli

This structure has been set up on the occasion of the IUGG General Assembly in Birmingham 1999 in order to cover the most important aspects of contemporary geodetic theory, and has proven to be highly efficient in the first half of the working period.

Besides the thematical work done in the various bodies of Section IV - which is reported below in detail - the planned changes of the IAG structure have played a central role in the past bi-annual period. In contrast to other IAG sections, the scope of Section IV is not confined to a specific topic in Geodesy such as positioning, or gravity field determination, or geodynamics; the accent here is rather on the systematic (mathematical) treatment of groups of problems. Therefore it is quite natural that most topics treated by the bodies in Section IV are shared in one way or another with other IAG sections, adding sometimes a different, more general point of view, but without just duplicating the work. Ideally, the mathematical problems occurring in the topic-oriented sections should be reflected upon in Section IV and solved on a general basis. Another principal scope of Section IV is to develop mathematical tools and to take up available approaches already developed in other fields of Science and to adept them to Geodetic Science; a prominent historical example is Least Squares Collocation which was developed in the seventies mainly in Section IV and nowadays is a basic tool in many branches of Geodesy. In recent years, e.g. spatial statistics, robust statistical methods, fuzzy theory and the use of wavelets have been thoroughly investigated in Section IV for applications in Geodesy; some of these approaches seem to be rather promising and to become highly efficient tools in geodetic data analysis. Concerning the plans for a new IAG structure it is scheduled to abolish the present sections and to replace them by four topic-oriented commissions, dealing with

  1) Geometric Reference Frames

  2) Gravity Field

  3) Earth Rotation and Geodynamics

  4) Positioning and Applications.

The task of these new commissions is to promote the advancement of science, technology and international cooperation in their field. Besides the services, the commissions will form the main components of the new IAG structure.

In the new structure an entity like the present section IV is no more foreseen and visible at the highest level of organization below the EC, the level of the commissions and services. But this does not mean at all that geodetic theory and methodology will not play a fundamental role anymore. Since one of the major tasks of the new commissions is the promotion of science, these bodies will be responsible for the development of theory and modelling in their respective fields, too. Of course, this procedure cannot include the development of general, topic-independent approaches of data analysis and mathematical-physical foundations, methodology and "general" theory of Geodesy. After many discussions a solution of this problem could be found, consisting of the creation of an inter-commission committee on general theory and methodology, reporting directly to the EC. It is expected that the existence of such a committee will make sure that e.g. mathematically interested geodesists and application-oriented mathematicians and physicists furthermore will find a home and meeting-place within IAG. The implementation of the new structure, to be approved during the IAG Scientific Meeting in Budapest in September 2001, is still a heavy task and a challenge for Section IV in the next two years.

In the past bi-annual period 1999 - 2001 Section IV contributed to different scientific meetings such as

- Seventh International Winter Seminar in Sopron/Hungary, February 19-23, 2001,

- International Symposium on Vertical Reference Systems, Cartagena/Columbia, February 20-23, 2001,

- First International Symposium on Robust Statistics and Fuzzy Techniques in Geodesy and GIS, Zurich/Switzerland, March 12-16, 2001,

and

-EGS General Assembly, Nice/France, March 25-30, 2001.

A strong input from Section IV will also be given to the IAG Scientific Meeting in Budapest/Hungary, September 2-8, 2001. Finally it is planned to continue the series of Hotine-Marussi Symposia on Mathematical Geodesy in 2002; traditionally Section IV has been strongly involved in these symposia, organized in Italy.

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