Report on Activities

Martin Vermeer



1. Establisment and Terms of Reference

The decision to establish this IAG Commission was taken in July 1999 in Birmingham, UK, at the IUGG/IAG General Assembly, merging the activities of the International Gravity Commission and the International Geoid commission. The objective was to establish a stronger focus for the scientific study of the gravity field of the Earth.

Terms of Reference were drawn up to guide the work of the Commission. They can be found at the Web address


2. The working groups of the Commission

2.1 The WG on Intercomparison of Absolute Gravimeters

The Working Group on Intercomparison of Absolute Gravimeters, headed by Leonid Vitushkin, has been particularly active. Dr. Vitushkin has worked to establish not only the IGGC's Working group, but a similar working group involving the same scientific community, but belonging to the sphere of international metrology under the auspices of the Bureau International des Poids et Mesures (BIPM, in Paris, France.

For this purpose the creation of a new Consultative Committee has been proposed for absolute gravimetry. The impetus for this was a letter (July 15, 1999) by three leading Russian geophysicists representing the National Geophysical Committee and its Geodesy Section, addressed to the President of IAG explaining the need to bring absolute gravimetric work within a metrological framework. The precise organizational arrangement is yet to be decided in October 2001 (Letter November 23, 2000, Jean Kovalevsky, Comité International des Poids et mesures).

The objective is to establish a close collaboration between the metrological community on the one hand, and the geodetic-geophysical community on the other.

In preparing these initiatives, Dr. Vitushkin visited Helsinki, Finland in October 4 - 6, 2000 on the invitation of the Director-General of the Finnish Centre for Metrology and Accreditation, Ulla Lähteenmäki. The undersigned participated in the discussions that took place.


2.2 The Arctic Gravity project

Also the Arctic Gravity Project (ArcGP), another working group within IGGC, was very active under the leadership of René Forsberg and the contructive attitudes of several circumarctic countries, among which Russia, the United States, Canada, Denmark and Norway.

In spite of the obvious political sensitivity of the stated objective of producing a gravity survey map of the Arctic Ocean at 5' resolution, good progress was made. Gravimetric data appears to exist from a large number of sources and techniques (shipborne, airborne, submarine, ice surface, satellite altimetry…) to cover all of the target area with the possible exception of a small banana shaped region.

The first meeting of the Working Group took place in St Petersburg, Russia, in a small mansion outside the city. The meeting, in which the undersigned participated, was both productive and pleasant.

A second meeting in Canada is to be convened these days.

The ArcGP has its own web site, address


2.3 The Antarctic Gravity Project

The Working Group on Antarctica of the IGGC has been headed by Alessandro Capra of the University of Bologna. Dr. Capra also heads the Physical Geodesy project within the Geodesy program (GIANT) of the Geodesy and Geographic Information group of SCAR, the Scientific Committee on Arctic Research.

The purpose of this WG is, similarly to ArcGP. the compilation of a gravimetric data base with a view of determining a high resolution geoid model of the Antarctic area. See the Web site


2.4 Other Working Groups

The creation of the following WG's was decided at the first IGGC Assembly

meeting in Banff, Canada, cf. section 5.1

WG on World Gravity Standards, chair Gerd Boedecker
WG on the Global Gravity Monitoring Network, chair Berndt Richter


3 The Subcommissions

The following Subcommissions have been established at the outset of the IGGC:

3.1 North America

The Subcommission for North America, chaired by Marc Véronneau, was off for a good start, with gravity and DEM measurement and compilation and geoid determination going on in several member countries. Meetings held include:

At the Canadian Geophysical Union meeting, Banff, May 2000;
At the GGG2000 meeting in Banff, Canada, see section 5.1
At the IAG Symposium in Cartagena, Colombia, see section 5.2or attendance.
The next official meeting is planned for May 2000 in connection again with the CGU meeting in Ottawa, Canada.

This Subcommission has also the Caribbean and Central America within its field of operations and letters of invitation were sent to all the countries of Central America, Cuba, The Bahamas and the Dominican Republic, which have not yet responded.

The Subcommission's Web site is at: (requires a password).


3.2 Europe

The Subcommission for Europe, chaired by Ambrus Kenyeres. A report on its activities was presented at the GGG2000 meeting. It can be found at

The Computing Centre for the European Geoid at the University of Hannover (Heiner Denker) has expressed an interest in continued involvement in this computational effort. It is intended, in close co-operation with EUREF, to use a highly reliable GPS/levelling data set as fiducial control for future geoid model determinations.


3.3 South America

The Subcommission for South America, headed by Denizar Blitzkow. A meeting has been held in Cartagena, Colombia, see section 5.2. Geoid determination activities for the area are ongoing, as are gravity surveys and establishment of digital terrain models.


3.4 South-East Asia

The Subcommission for South-East Asia, headed by Bill Kearsley. Activities in this area are hampered by the lack of an existing IAG framework for co-ordinating activities in the region. Nevertheless, as a success can be reported the IAG Geoid School in Johor, Malaysia, in February 2000.


4 Services

The Services currenty under the auspices of the IGGC are:

The Bureau Gravimétrique International, Toulouse, France. Director: Jean-Pierre Barriot (taking office 1999).
The International Geoid Service, Milano, Italy. Director: Fernando Sansó.

Both services have been active in their mandated fields of activity. It should be stressed that the operations of both are made possible mostly by national sources of financing within France and Italy, respectively. The IGGC can only play a co-ordinating role for both in order to enable them to better execute their mandates.

A first Directing Board meeting of both services was held during the Banff meeting,

cf. section 5.1.


Web sites of both services are:



5 Meetings

5.1 Banff

At the GGG2000 (Gravity, Geoid, and Geodynamics) meeting, July 31 - August 4, 2000, in Banff, Canada, the Assembly of the IGGC met for the first time, on the first of August. A number of decisions was taken, mainly confirming the proposed study groups and subcommissions and their chairpersons, as well as the terms of Reference. The Minutes are found here:


5.2 Cartagena

A symposium called the IAG Symposium on Vertical Reference Systems was convened February 20 - 23, 2001 in Cartagena, Colombia, where besides the Subcommission for South America, also the Subcommission for South America met in a splinter meeting.

Unfortunately the undersigned was unable to attend, but a letter was sent to the organizers expressing the support of the IGGC to the symposiom, and expressing good wishes for its success.


5.3 Nice

In preparation for the 2001 meeting of the IAG Executive Commmittee, a proposal was circulated drafted by several people within the Executive, aimed at the creation of a GFFS, ”Gravity Field and Figure of the Earth Service”,

which would serve as a formal umbrella for

The International Geoid Service
The Service International des Marées Terrestes

 and a couple of services to be newly established. One such service, for which official support was promised by the GeoForschungsZentrum in Potsdam, Germany (Letter Ch. Reigber , March 23, 2001), was a Service for the Intercomparison of Global Spherical Harmonic Expansions.

The publication of a joint Information Bulletin is envisaged.

The undersigned asked the proposal to be placed on the agenda for discussion; unfortunately again such discussion took place in his absence forced by other commitments.


6 Web site

A web site, for the Commission was set up and s being maintained by the Secretary, Jacques Liard at his affiliation, Natural Resources Canada. Their provision of hosting facility and bandwidth is gratefully acknowledged.



TABLE OF CONTENTS                                                          TOP