PRESIDENTIAL ADDRESS

International Association of Geodesy

XXI IUGG General Assembly

Boulder, Colorado, July 1995

by Wolfgang Torge

Distinguished Guests,

Dear Colleagues,

Ladies and Gentlemen,

I have the honour to welcome you at the opening of the IAG General Assembly, which our Association traditionally holds within the frame of the IUGG General Assembly. I should like to especially welcome the President of the International Union of Geodesy and Geophysics, our colleague Professor Helmut Moritz, and the President of the International Union of Surveys and Mapping, Mr. Earl James, who is also the President of the International Federation of Surveyors. My greetings also go to the representatives of our sister organizations, united in the IUSM.

I should like to also inform you that our Honorary President Professor Bomford will reach the age of 96 years this week and I propose to send a message of congratulation to him. I now come to the Presidential Address, which will report on some major accomplishments of IAG, achieved during the last four years. In addition, I shall try to indicate some future tendencies and actions.

But at first it is my duty to remember our friends who left us since the last General Assembly. We lost

Richard Anderle, USA

Arpad Czobor, Hungary

Czeslaw Kamela, Poland

Georges Laclavère, France, Secretary General of IUGG from 1951 -1963

Mikhail Sergevich Molodensky, Russia

Gabriel Obenson, Cameroon

Leonard Pavlovich Pellinen, Russia

Avraam Perelmuter, Israel

Donald A. Richardson, USA

Karl Rinner, Austria

Ove Simonsen, Denmark

Charles Whitten, USA, IAG-President from 1963 to 1967

Helmut Wolf, Germany, and

Tadeusz Wyrzykowski, Poland.

May I ask you to stand up for a minute of silence to honour the memory of our colleagues. Thank you.

Let me now make a few notes on the historical relation between the IAG and our host country. As you know, IAG has its roots in the "Mitteleuropäische Gradmessung", established in 1862 in Central Europe. The extension to the International Association of Geodesy occurred in 1886, and a significant break-through towards a global international organization happened, when the United States of America joined IAG in 1889. An Act of Congress (21.2.1889) authorized the President of the United States to appoint a delegate to the Association, and at the General Conference in Paris, in October 1889, the U.S. Delegate George Davidson, Assistant U.S. Coast and Geodetic Survey, brought kind greetings and expressed the "conviction that (the Association's) views will grow with the breadth of the new world before it." A detailed report about the geodetic activities in the United States followed, including the manifold work along the 39th parallel. Since that time, the United States have been a very active member of IAG, as demonstrated by the

Presidents William Bowie (1920 - 1933),

Walter D. Lambert (1946 - 1951),

Charles Whitten (1960 - 1963), and

Ivan Mueller (1987 - 1991),

and IUGG/IAG General Assemblies held in Washington (1939) and in Berkeley (1963). Taking the outstanding contributions of the United States to Geophysics and Geodesy into account, it was certainly high time to meet again in this country.

I now come to the scientific achievements over the last period. These achievements are of course due to the work of the individual scientists, who engage themselves in IAG bodies as Sections, Commissions, Special Study Groups, Services and projects, and the next two weeks will demonstrate in detail their activities and results. Having with the five sections a very strict scientific structure, it is only justified if the Section Presidents later at this opening session shortly inform about highlights of their work. Nevertheless I should like to make a few more general statements about the present state of geodesy, and in this connection also refer to some new or successfully continued IAG activities.

If we classify the fundamental geodetic tasks into reference systems, positioning, and gravity field modelling, we first have to recognize that the observation techniques now approach or have reached the 10-9 accuracy on global and regional scale, and that modern data acquisition systems allow a very high time sequence of the observations. In addition, kinematic survey methods system more and more govern geodesy employing artificial satellites as well as airborne and land vehicle systems. This progress in technology has raised many problems and posed partly unexpected challenges. IAG by coordinated efforts tried to promote the study of those problems, especially through international cooperation. Important research areas can be read off from the present IAG structure, and include a much more refined functional modelling of geodetic observations into geodetic parameters, taking the increased accuracy and time variations into account, and extending those models to kinematic methods, a deeper understanding and modelling of the observational errors at high data rates, taking non-random effects and frequency dependence into account, new studies of the geodetic boundary value problem, under the aspect of available space data, as well as improved models of the upper layers of the Earth, design problems of geodetic fundamental and geodynamic networks, combining different observation techniques, interpretation of global regional and local geodetic data within the frame of geophysical models and jointly with geophysical data sets, from the static and the dynamic point of view.

Let me mention - without any completeness - some of the overall IAG activities, generally with interdisciplinary character, and including collaboration with other scientific bodies:

The International Earth Rotation Service (IERS) continued to work with great success as a joint enterprise of IUGG and IAU since 1988. Providing the basic reference frames by employing advanced space methods, the evaluation and interpretation of the results has brought an enormous progress at our understanding of the kinematic and dynamic behaviour of the Earth, and linked together practically all fields of IUGG, with astronomy and space research, at continental dimensions, reference frames are under construction, fitting into the IERS frame and employing GPS-techniques. These activities more strongly connect geodesy to cartography and surveying, and - in general - to all kind of geoinformation systems. Examples of this type of work are the European Reference Frame now extended to Eastern Europe, and the SIRGAS project in South America, both running in close cooperation with the national Geodetic Surveys, the International GPS Service for Geodynamics started routine work on January 1, 1994, and proved to be extremely successful. In close cooperation with the IERS, well - accepted products are provided to users in high - precision and in practical geodesy. Especially, the IGS represents an efficient tool, to monitor the local and regional strain-field of the Earth, as an important boundary-condition in geodynamics research.

I should like to thank here all the individuals and agencies involved in IGS, and as representatives I mention Gerhard Beutler, the Chairman of the IGS Governing Board, and Ivan Mueller, who initiated the Service, the ad-hoc planning group on Global Change, established after Vienna and chaired by Jean Dickey, identified IAG related problem areas, and succeeded to link geodesy to the International Geosphere-Biosphere-Program, within the Core-Project "Land-Ocean Interactions in the Coastal Zone", the International Geoid Service, located at Milano, is operational since 1992, and provides effective support to individuals and agencies, involved in geoid determination, while Regional Subcommissions as for Europe and South America push forward calculations on a continental scale, the links to our sister organisations have been strengthened through our involvement in the International Union of Surveys and Mapping (IUSM). IAG could contribute to the IUSM Working Groups on GPS, on Engineering, on Education, and on Geographical Information Systems, and joint meetings on the first three topics will be held here in Boulder, finally, I mention one outcome of our active GALOS group, chaired by Petr Vanicek, which is the establishment of an IHO (International Hydrographie Organization) / IAG Advisory Board on Hydrographic and Geodetic Aspects of the UN Convention on the Law of the Sea.

Research work done and results obtained, again have been discussed and documented in scientific meetings sponsored by IAG, and in the IAG related publications. Following our tradition, IAG sponsored more than 30 symposia, workshops, summer schools and seminars, during the past four years. We were happy to again have a General Meeting between the General Assemblies, in 1993 in Beijing, with six dedicated topics, and a strong emphasis on the contribution of geodesy to global change problems. Let me thank again our second Vicepresident Dr. Chen, who was responsible for the organisation of the successful meeting. We tried to also offer an interesting palette of topics at this General Assembly, with strong emphasis on interdisciplinary aspects. As you have recognized from the program, IAG is involved in 6 Union Symposia and 13 Inter-Association Symposia, convening 2 respectively 3 of them. In addition, we shall have 3 IAG-Symposia, 4 Intersection-Symposia, and the 5 section meetings. We already have proposals for a number of symposia to be held in the next period, and we especially have received invitations from Brasil and from Australia, to hold the next "General Meeting", which we shall call now "Scientific Assembly" in those countries in the year 1997.

For internal communication and discussion, but also for showing up geodetic research results and geodetic products to the outside world, IAG has different possibilities and we also had some progress in this field. First of all, I can announce here, that the two journals "Bulletin of Geodesique" and "manuscripta geodaetica" will unite on January, 1. 1996, and a "Journal of Geodesy" as the official journal of IAG will be published then at Springer publisher, with one issue per month. Let me thank here the two chief-editors of BG and mg, Christian Tscherning and Petr Vanicek, as well as the Editorial Board of Bg/mg for their engagement. A report will be given here by Christian Tscherning. Another effort to document the IAG work are the IAG Symposia Proceedings started in 1989. Up to now 13 volumes have been published, one is in press and two more are planned as an outcome of this General Assembly. We continue of course with the "travaux" or "proceedings" of the General Assemblies, and with the IAG-Newsletters, in our new Journal. The Central Bureau has established an IAG Information Service on Internet, with a large variety of interesting details about IAG. I should like to thank the IAG Assistant Secretary Pascal Willis, for his hard work in order to establish and improve the Newsletters, the Information Service and the Travaux, as well as for his other manifold activities. I should also mention, that a number of IAG bodies regularily publish their information bulletins, thus very efficiently contributing to the exchange of ideas and the progress in the corresponding research field. Thanks to all the responsible editors for their strong engagement

I now come to an item, where IAG, and this is the total of scientists affiliated to IAG, can be especially proud of. As you know, we have introduced in Vienna 1991 the categories of IAG Fellows and Associates, in order to create a more personal relation of individuals to our Association. About 200 Fellows and more than 1000 Associates have by now declared their affiliation to IAG. In 1993, the IAG President started an initiative to establish an IAG Fund, by voluntary contributions from the Fellows, and later also from the Associates. This action was extremely successful, and I very warmly thank all the contributors for their immediate positive reaction. The Fund is managed completely independent from the IAG budget and the Fund's reserves are only used for three dedicated purposes, which are an annual best paper award for young scientists, and the award winner for 1993 and 1994 will be announced later, a travel award for young scientists and among the about 15 scientists supported for attending this General Assembly, four have received support from the Fund, the support of IAG workshops in developing countries, and planning is underway, to organize and support such a workshop within the next years.

My thanks go to the 1. Vicepresident Klaus-Peter Schwarz and to Ivan Mueller, who took over the efforts of the Fund raising. IAG feels a special responsibility to promote geodetic activities in developing countries as explicitely stated in the IAG Statutes. Although progress is slow, some positive records can be given here. A number of symposia either took place in third world countries, or concentrated on geodetic problems in that areas. As examples I mention the Symposium on Geodesy in Latin America in Vienna 1991, and the forthcoming Symposium on South East Asia, to be held here in Boulder, as well as Symposia or Workshops in Maracaibo, Bali, Lagos and Nairobi held between 1992 and 1994. A successful enterprise was the establishment of a Committee for Developing Countries in 1992, chaired by our Honorary Secretary General Michel Louis. With the Courier for Development, this group has remarkably improved the information lines and triggered new activities. Coming to projects, I should like to mention the extremely well running SIRGAS project, jointly sponsored by IAG, PAIGH, and DMA, with the intention to establish a zero order reference system in South America, and to tie the national control nets to that system. I should like to thank here especially the SIRGAS president Ing. Fortes from Brazil. Another example is the Geoid Subcommission for South America, which started in 1994, and gives another example how regional activites within the frame work of our commissions can promote geodetic activities from the scientific as well as from the application point of view.

Looking forward, I try to identify a few areas of future activities, at developping internal IAG-structures, as well as relations to geosciences, engineering and the field of geoinformation systems:

The IAG structures will be again revised and adapted to the new requirements, by the Cassinis-Committee set up here in Boulder. The Committee certainly has to evaluate if the present structure has to be modified, but also how IAG could react more flexible to challenges from the outside, and trigger initiatives in geosciences. I remind you that a "Cassinis Forum" will take place on Monday, 9. July, in the evening 19.00, and I invite you to discuss then the problems existing and to collect ideas about the future of IAG, IAG certainly should try to even more involve young people. There is again one chance here at the Assembly: The "old boys" should identify qualified young people, and include them into the IAG work, especially into the Special Study Groups. The youngsters on the other hand, should actively bring in their ideas and enter into the IAG bodies, they can and must stimulate our Association, IAG should continue and strengthen its activities with respect to developping countries. I think, that the establishment of regional subcommissions for dedicated tasks as geoid determination is one adequate tool in that direction. Another one is the joint realization of projects, and of course symposia and workshops related to problems in those regions should be supported even more.

Obviously, the promotion of young scientists and the support of activities in developping countries strongly depends on the financial basis. Under that point of view, IAG should improve and extend its services, and in that way directly or indirectly involve young scientists, and scientists from developping countries in IAG work, and continue the building-up of an individual feeling of an "IAG-membership", through the Fellows and Associates. The IAG Fund has opened a chance to remarkably strengthen our support, and more than 1000 affiliates even by a small annual contribution could significantly contribute.

I now come to the announcement and lending of some IAG awards. As I mentioned earlier, one outcome of the IAG Fund is the IAG Best Paper Award for Young Scientists with the purpose to draw attention to important contributions in the Bulletin Geodesique or manuscripta geodaetica, and to foster excellence in scientific writing. For the year 1993, the award is given to Dr. Hussein Abd-Elmotaal. Born in Cairo in 1960, he studied at Ain Shans University and at Graz University of Technology, and he is now Assistant Professor at Minia University, Egypt. He receives the award for his paper "Vening Meinesz Moho depths: traditional, exact and approximated", published in manuscripta geodaetica vol. 18, no. 4, 1993. For 1994, the award winner is Dr. Jean-Pierre Barriot. Born in 1959, he studied at Montpellier University, and held postdoctoral research positions at the French Space Agency and at Jet Propulsion Laboratory. He is now research engineer at CNES in France. The award is given for his paper "Line of sight operators in planetary geodesy", published in manuscripta geodaetica, vol. 19, no. 5, 1994.

I am now going to announce the award of the Levallois medal. This medal was established by IAG in 1979, to honour our former Secretary General and his outstanding contributions to IAG. The award is made in recognition of distinguished service to the Association, and/or to the science of geodesy in general. I have the great honour to inform you that the Nomination Committee proposed, and the Executive Committee confirmed, that the Levallois medal shall be awarded to Professor Willem Baarda. Prof. Baarda worked for several decades at the Technical University at Delft, Netherlands, and the results of his research strongly influenced geodesy. He was the first to develop a systematic framework of statistical quality control, including the famous "data snooping". He also firstly introduced criterion matrices for testing a network precision, and invented the reliability concept, now at widespread use. Finally, I mention the invention of the S-transformations, nowadays employed at "free network" adjustments. Some of Prof. Baarda's publications from the 1960's and 1970's belong to the fundamental literature in geodesy. Just a few days ago, I even received a new basic publication from Prof. Baarda, related to the coupling and interaction between geometric and physical geodesy. Prof. Baarda received many honours, and he is a member of several scientific academies. For IAG he served as a member of the Cassinis Committee, as the Chairman of Special Study Groups on Networks and Statistics, and as a member of the Commission on Education.

Through the Levallois medal, IAG recognizes the outstanding scientific contributions of Prof. Baarda to geodesy, and especially expresses its gratitude for his service to IAG. Unfortunately Prof. Baarda could not attend the General Assembly, but the Netherlands Geodetic Commission and Delft University will organize an appropriate event within the next few months, and I then shall hand over the medal to him.

And now, last not least, I come to the Bomford Prize. This prize was inaugurated by IAG in 1975, and it is given at four years intervals, to a young scientist for outstanding theoretical or applied contributions to geodetic studies. Five very qualified young scientists have been nominated by the National Committees, and after a careful review process, the Prize Committee decided to award the Guy Bomford Prize 1995 to Professor Thomas A. Herring. Dr. Herring was born in 1955 in Cooroy/Queensland, Australia. He was educated at the University of Queensland, with a Bachelor and Master Degree in Surveying, and at the MIT, with the Ph. D. Degree. His scientific carreer includes positions at the University of Queensland and at Harvard University, and he is now Associate Professor of Geophysics at the Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology. From his many professonal activities I mention his engagement in IAG research groups on atmospheric refraction, and on the application of space-based interferometry, in the IAU Working Group on Astronomical Standards, and in Committees or panels of the National Academy of Sciences, NASA, and AGU.

Tom Herrings career has been marked by leadership in the use of space-geodetic measurements to study the properties of the Earth. His first paper established the ability of VLBI to measure continental baselines with cm precision. Five years later, he and his colleagues published the first conclusive evidence from VLBI of plate motions. The improved analysis of VLBI data also led to an empirical nutation model which is currently used at the IERS. In the past four years, Tom Herring continued his VLBI studies, but now also made important contributions to GPS measurements of global and regional geodynamics, and demonstrated that earth rotation variations can be derived from GPS. An outstanding example for combination techniques developed for time series of heterogeneous data sets is the determination of the velocity field for Southern California from VLBI and GPS observations spanning eight years. By combining a critical understanding of the inherent deficiencies in space-geodetic measurements with a vision of their potential accuracy, Tom Herring has consistently pushed the analyses to higher levels, based on his fundamental knowledge of geodetic observations, Earth models, and Astronomy.

IAG is proud to award the famous Bomford Prize to you, Dr. Herring.

Let me conclude the Opening Ceremony by reminding you that our old and still young Association depends on all of you, on your engagement, on your positive criticism, and on your proposals for the future direction. Looking back on four years of office, I am optimistic that IAG is able to renew itself continuously, and this optimism is based upon the support and the input I had during the last four years from so many colleagues. I have mentioned some of them already, but I especially want to thank the Bureau members and the members of the Executive Committee, as well as all the IAG officers: I enjoyed the work with you. Sincere thanks have to be expressed to the Institut Géographique National of France, which hosted the IAG Central Bureau over more than 70 years, and to all the Secretary Generals and Assistant Secretaries, who served IAG over this time span. Let me especially thank Jean Dickey, our representative at the Organizing Committee: you did an excellent job at the organization of this very complex event. I wish you all an interesting meeting, with fruitful discussions, getting new ideas for the future work, finding new friends, and strengthening the relations within our Association, the IAG, and to our sister organisations.

I now declare the IAG General Assembly to be opened.