G. Beutler
on behalf of the
IAG Committee for the
Realization of the New IAG Structure
Members of the
IAG Committee for the
Realization of the New IAG Structure:
"Alan Dodson"
<Alan.Dodson@nottingham.ac.uk>
"Bernhard Heck"
<heck@geomatics.ucalgary.ca>
"Klaus Peter Schwarz"
<schwarz@geomatics.ucalgary.ca>
"C.K. Shum" <ckshum@osu.edu>
"Michael G. Sideris"
<sideris@ucalgary.ca>
"Clark Wilson" <clarkw@maestro.geo.utexas.edu>
"C.C.Tscherning"
<cct@gfy.ku.dk>
"Ruth E. Neilan"
<ruth.neilan@jpl.nasa.gov>
"Manning John"
<johnmanning@auslig.gov.au>
"Fernando Sanso"
<fsanso@ipmtf4.topo.polimi.it>
1.
Introduction and Overview....................................................................................................................
3.
Commission 1 (Task Leader: C.K.
Shum)............................................................................................
4.
Commission 2: Gravity Field (Task
leader: Michael G. Sideris)...............................................................
5.
Commission 3 Earth Rotation and Geodynamics (Task Leader: Clark Wilson).........................................
6.
Commission 4 Positioning and Applications (Task leader Alan Dodson)..................................................
7.
Inter-Commission Committee on Theory (Task
leaders: Bernhard Heck and Peiliang Xu)..........................
8.
Inter-Commission Committee on Geodetic Standards (Task leader Clark
Wilson).....................................
9.
Outreach Branch (Task leader: Christian Tscherning).............................................................................
10.
IAG Project IGGOS (Task leader: Gerhard Beutler)................................................................................
11.
Summary and Action Items.................................................................................................................
12.
References........................................................................................................................................
Introduction and Overview
The new IAG structure was
developed after the IUGG General Assembly in Birmingham in summer 1999. Between
summer 1999 and summer 2001 a thorough review of the IAG work and structure was
performed by the so-called IAG Review Committee, the work of which is
documented in (Beutler et al., 2001), a report which was presented at the IAG
Scientific Assembly in Budapest in September 2001 in Budapest. At the same
meeting, the proposed new structure was accepted by the IAG Executive Committee
and later on by the IAG Council, which held an extraordinary meeting on
September 8, 2001 in Budapest.
At the same meeting (Rummel
et al., 2001) proposed to create the IGGOS, the Integrated Global Geodetic
Observing System as IAG’s first project.
It is worthwhile to cite a
few lines from the new IAG Statutes and IAG By-Laws, which were accepted by the
IAG Council at the September 8, 2001 meeting. According to these Statutes the
Mission of the Association is defined as:
The MISSION of the
Association is the advancement of geodesy, an earth science that includes the
study of the planets and their satellites. The IAG implements its mission by
advancing geodetic theory through research and teaching, by collecting,
analyzing, and modeling observational data, by stimulating technological
development and by providing a consistent representation of the figure,
rotation, and gravity field of the earth and planets and their temporal
variations.
The Association’s objectives
are subsequently stated in the IAG Statutes. The future scientific work of the
Association is further specified in the new IAG By-Laws:
The scientific work of the
Association is performed within a component-structure consisting of
Commissions, Services, the Communication and Outreach Branch, and IAG Projects,
hereafter called the Association-components or components.
The new ByLaws allow it
furthermore to establish Inter-Commission Committees, where the following rules
shall be observed according to the IAG ByLaws:
Inter-commission Committees
shall handle important and permanent tasks involving all commissions. Each
Inter-commission Committee shall have a steering committee consisting of the
following membership:
The terms of reference for
each Inter-commission Committee shall be developed by a planning group
appointed by the IAG Executive Committee. The Inter-commission Committees
report to the IAG Executive Committee. The Inter-Commission Committee will be
reviewed every eight years.
The following specific tasks
were identified in Budapest to be achieved between the IAG Scientific Assembly
1999 and the IUGG General Assembly 2003 in Sapporo:
A call for proposals should
be issued for the the new Communication and Outreach Branch
The work of mapping the old
structure into the new one, of creating the planning group for the ICC on
Theory, and of issuing the call for the outreach branch was given to the IAG Committee
for the realization of the new IAG structure. It was decided furthermore that
the creation of a planning group for the IAG Project called IGGOS (Integrated
Global Geodetic Observing System) should be left to the initiative of Reiner
Rummel and Gerhard Beutler (see section 10 of this report).
The planning group for the
Inter-commission Committee on Theory was set up early in 2002. The group
members are:
The discussions within this
group and of the group with a broader community were rather intense, but very
interesting. A convergence was reached and summarized in an e-mail sent out by
the Chairman on July 2, 2002. The outcome of the work is presented in section 7
of this report. It is in essence based on a summary by Bernhard Heck and the
first report of the Planning Group compiled by Peiliang Xu.
The IAG Committee for the
realization of the new IAG structure held three meeting (on September 6, 2001
in Budapest, on December 11, 2001 in San Francisco, and on April 26, 2002 in
Nice).
The five Section presidents
agreed to serve as task leaders for the creation of the four new commissions
and the Inter-Commission Committee on Theory. The outcome of their work will be
summarized in sections 3-7. Christian Tscherning, IAG Secretary General, is the
task leader for the establishment of the Communication and Outreach Branch.
At its meeting in Nice the
Committee decided to support a proposal made by Proff. Erwin Groten (who was
invited to attend the Nice meeting) and Erik Grafarend to create an
Inter-commission Committee on Geodetic Standards. It was furthermore decided
that Section V should take the leadership in the planning group for this
committee, and that the IAG services, in particular the IERS, IGS, IVS, ILRS,
and the gravity-related services should be represented in the planning group.
(The IAG EC actually asked Clark Wilson, president of Section V to chair this
planning group and to create it with prominent representation from the
services, in particular from the IERS, the IGS, IVS, ILRS, and the
gravity-related services.)
The New Structure in Overview
The services associated so
far with the IAG were invited to become official IAG Services under the new structure.
The following services made the decision to follow this invitation in the sense
defined by the new IAG Statutes and By-Laws:
The IAG services work and act
in a relatively independent way. Their decision to join the IAG as services in
the sense of the new statutes and by-laws could not be „enforced“ by the IAG.
The Committee on the Realization of the New Structure is very much pleased by
this positive response.
According to the IAG By-Laws
the following four commissions shall be set up:
Commission 1 Reference Frames
Objectives:
a. Establishment,
maintenance, improvement of the geodetic reference frames.
b. Advanced
terrestrial and space observation technique development for the above purposes.
c. International
collaboration for the definition and deployment of networks of
terrestrially-based space geodetic observatories.
d. Theory and
coordination of astrometric observation for reference frame purposes.
e. Collaboration with
space geodesy/reference frame related international services, agencies and
organizations.
Commission 2 Gravity Field
Objectives:
a. Terrestrial,
marine, and airborne gravimetry.
b. Satellite gravity
field observations.
c. Gravity field
modeling.
d. Time-variable
gravity field.
e. Geoid
determination.
f.
Satellite orbit modeling and determination.
Commission 3 Earth Rotation and
Geodynamics
Objectives:
a. Earth Orientation
(Earth rotation, polar motion, nutation and precession).
b. Earth tides.
c. Tectonics and
Crustal Deformation.
d. Sea surface
topography and sea level changes.
e. Planetary and
lunar dynamics.
f.
Effects of the Earth's fluid layers (e.g., post glacial rebound,
loading).
Commission 4 Positioning and
Applications
Objectives:
a. Terrestrial and
satellite-based positioning systems development, including sensor and
information fusion.
b. Navigation and
guidance of platforms.
c. Interferometric
laser and radar applications (e.g., Synthetic Aperture Radar).
d. Applications of
geodetic positioning using three dimensional geodetic networks (passive and
active networks), including monitoring of deformations.
e. Applications of
geodesy to engineering.
f.
Atmospheric investigations using space geodetic techniques.
Each Commission shall have a
Steering Committee, with a maximum of twelve voting members, which shall define
the appropriate sub-structure of the Commission, which may consist of the
following components:
A planning group for the
IGGOS was set up, a first meeting was held in May 2002 in Washington, a second
in October 2003 in Munich. The proposal of this group is contained in the
separate document (Beutler, Drewes, Rummel, 2003). The status of the
realization of the prominent elements of the new IAG structure is summarized in
the following sections.
Commission 1 (Task Leader:
C.K. Shum)
This proposal emerged from
discussions in Nice before, at the, and after the third meeting of the IAG
Committee for the Realization of the New IAG Structure on April 26, 2002. It is
proposed to set up the following Sub-commissions (SC):
Take over the coordinating role of its predecessor CSTG in a changed environment. The SC shall establish and further the contact of the space geodetic services based on space techniques, in particular IERS, IGS, ILRS, IVS and commission projects like DORIS.
Address
research-related and practical aspects of establishing the global reference
frame. Address fundamental issues of the multi-technique global geodetic
observatories. This SC must play a strong role in the new IAG project IGGOS.
Its activities shall be coordinated with the IERS. SC1.3 shall in particular
establish and maintain the contact with COSPAR.
SC1.3 shall offer
a home for service-like regional reference frame activities AND address common
aspects of these units. In order to avoid the creation of sub-sub-commissions ,
it is proposed to formally establish
with the
understanding that these subcommissions also form the steering committee of
SC1.3. Aspects of common interest shall be addressed, combined workshops,
sessions at workshops, etc. shall be organized.
This SC shall
address problems of satellite dynamics, which are outside the scope of the
services. One might, e.g., think of the materialization of the celestial
reference frame in satellite geodesy as a central theme, where aspects like the
transfer of the Quasar-derived frame into the optical domain, but also the the
value of modern high-accuracy astrometric places (based on modern telescopes,
CCD-equipment) could be addressed.
The following three
Commission Projects are proposed:
The project shall
promote the free access to all satellite altimetry data and its use for
geodetic reference frames, in particular height systems. It shall set up the
basis for a unified multi-mission long-term record of altimeter data and
investigate new techniques and application areas of satellite altimetry (e.g.,
off-nadir altimetry, altimetry over land, laser altimetry etc.). The necessary
steps towards the establishment of an altimetry service shall be studied.
The main objective
of this project is the coordination of geodetic activities with respect to the
new global navigation satellite systems. The links to the international bodies
involved in the establishment of new missions and systems shall be maintained
and intensified. The adequate use of GNSS for geodetic applications shall be
studied in cooperation with the subcommissions of Commission 1.
The project shall
coordinate the establishment of a DORIS service. In this task, it is
cooperating closely with the other components of Commission 1 and the existing
IAG services in this field (IERS, IGS, ILRS, IVS). The project will be
discontinued as soon as a DORIS Service is installed.
Commission 2: Gravity Field (Task
leader: Michael G. Sideris)
The new
Commission is derived mainly from the existing Section III (Determination of
the Gravity Field), with elements of Sections II, IV and V. When mapping the
old into the new structure, one may argue that the new Commission 2 should
consist of the existing Section III, of Special Commission 7 (Satellite Gravity
Field Missions) from Section II, of Special Commission 1 (Physical Foundations
of Geodesy) with Sub-commission 3 (Boundary Value Problems)
from Section IV, and even of part of Comission 5 (Earth
Tides) from Section V. Of course the latter can fit as well under the new
Commission 3 (Earth Rotation and Geodynamics).
Although the
theoretical aspects of SC1 and its sub-commission 3
could be covered under the proposed Inter-Commission Committee on Theory, it is
felt that their natural place is under the new Commission 2, with full
cooperation and coordination with the activities of the Inter-Commission
Committee.
The five major
thematic areas of the new Commission 2 will be:
Based on the
above themes. there are currently only three major elements planned, that will
define the structure of Commission 2. In terms of Sub-commissions, these are:
The proposed
SC2.3 might be part of SC2.1 or SC2.2, but, given
the very high importance of the new satellite missions, it is felt that, at
least initially, there should be a separate sub-commission to deal with the
special issues and the variety of applications of these missions. Several study
groups similar to the ones that exist currently would again be established to
(i) investigate more specific topics and (ii) coordinate regional efforts of
gravity mapping, geoid determination, vertical datums, etc.
Commission 2 has very strong
links to the newly established International Gravity Field Service
(IGFS). consisting of:
IGFS’s terms of reference are available
under a separate document. It is clear that the givenning bodies of Commission
2 and IGFS should have a few common members on their Boards to ensure constant
communication and proper coordination of their activities.
Commission 3 Earth Rotation
and Geodynamics (Task Leader: Clark Wilson)
As discussed at the IAG
reorganization planning meeting on April 26, the new Commission 3 Earth
Rotation and Geodynamics, replaces Section V Geodynamics in the current
structure. Activities not proposed to be included in the two subcommissions
below are proposed to be assigned as follows:
Commission 3 is proposed to
consist initially of two subcommissions:
This proposed
subcommission includes activities now under Commission XIV in the current IAG
structure. The present Subcommission XIV contains sub-units related to
particular geographical regions, including long-standing projects such as
WEGENER, APSG, and the Central European Initiative, as well as Africa and
Antarctica. The objectives of the current Commission XIV (described on its
website http://www.df.unibo.it/commXIV/) are proposed to continue: First, to
study 3-D motions, in active tectonic regions, post-glacial rebound and
sea-level fluctuations and changes in relation to vertical tectonics along many
parts of the coastlines and in relation to environmental fluctuations/changes
affecting the geodetic observations; Second, to promote, develop and coordinate
international programs related to observations, analysis and data
interpretation for the three fields of investigation mentioned above; Third to
promote the development of appropriate models.
This proposed
subcommission includes activities within the IERS Global Geophysical Fluids
Centers (GGFC). There are 7 special bureaus organized to examine the influence
of the earth's mobile constituents (fluids) on the earth's orientation, defined
broadly in terms of length of day, polar motion, nutations, geocenter and
gravity. The 7 special bureaus are concerned with estimating influences of the
core, mantle, oceans, terrestrial hydrology, atmosphere, and ocean tides.
Activities under the present Special Commission 8 (Sea Level and Ice Sheets) are
expected to be incorporated within the appropriate special bureaus. This
proposed subcommission will follow the current goals of the GGFC (taken from
the GGFC website http://bowie.gsfc.nasa.gov/ggfc/): to compute time variations
of angular momenta and related torques, gravitational coefficients, and
geocenter shift for all geophysical fluids based on global observational data,
and/or products from state-of-the-art models, and to conduct scientific
sessions at international meetings and conferences.
Commission 4 Positioning and
Applications (Task leader Alan Dodson)
The new Commission 4 will
focus on multi-sensor applications, kinematic positioning, atmosphere
propagation, monitoring of local geodynamic applications, etc.
The Commission shall have
strong links to IAG-external organisations like FIG, ION, and (perhaps) to
ISPRS. IAG-internally, the Commission must be linked to the IGS (implying an
IGS representation on the Commission's steering committee).
Proposed Sub-commissions:
Two commission projects are
proposed:
Open issues still are: the
terrestrial systems, the height system.
Inter-Commission Committee on
Theory (Task leaders: Bernhard Heck and Peiliang Xu)
The proposed Terms of
Reference for the Inter-Commission Committee on
Theory are:
Structure of the ICCT:
The working groups also might
be called study groups.
Inter-Commission Committee on
Geodetic Standards
The planning group should be
established as soon as possible.
Outreach Branch
The process of setting up the
Outreach Branch is in the hands of the secretary general.
IAG Project IGGOS (Integrated
Global Geodetic Observing System)
The IGGOS
planning group is chaired by Gerhard Beutler till summer 2003, Hermann Drewes
is the planning group’s secretary. The group met twice, once in Washington and
once in Munich.
The planning
group held a first meeting in Washington on May 27, 2002 in Washington. The meeting
was intense and at times controversial. The establishment of IGGOS seemed to be
far from trivial. A vision and a mission statement as well as objectives for
IGGOS were subsequently proposed by Gerhard Beutler, Jim Ray, John Manning,
Hermann Drewes, and Reiner Rummel.
The second meeting of the
planning group took place on November 22, 23 in Munich at DGFI, the German
Geodetic Research Institute. This meeting was extremely constructive and
successful. In a first phase the vision, mission and objectives for IGGOS were
briefly reviewed and finalized (to the extent that such statements may ever
reach a final form).The agreed upon version of the IGGOS vision, mission, and
objectives are reproduced in this document. The primary (and ambitious) goals
of the November 2002 IGGOS planning group meeting were to reach a consensus on
the following four aspects:
The meeting resulted in the
proposal to actually establish the IGGOS as IAG’s first project. The full text
is contained in the reference (Beutler, Drewes, Rummel, 2003).
Summary and Action Items
Summary: The present
document gives an overview of the status of the IAG Restructuring process. The
process is complex and needs to be finalized between the two IAG Executive
Committee Meetings in Nice (April 2003) and in Sapporo (July, 2003). The work
must be performed mainly by the IAG Bureau, the five section presidents, and
the newly elected IAG officers.
Specific concerns were
brought forward by Bernhard Heck. They are not yet resolved, which is why this
task has to be addressed by the same group in the time frame mentioned above.
The concerns are:
Thanks to the work of
Bernhard Heck, Peiliang Xu, Véronique Dehant, and the entire ICCT planning
committee we now have a concrete proposal concerning the objectives and the
structure of the new Inter-Commission Committee on Theory.
No progress was made up till
now with the ICC on Geodetic Standards. We should have concrete proposals at
the Nice Executive Committee meeting. Otherwise the ICC on Standards cannot be
set up in Sapporo.
It should be possible to
formally establish the definition phase for IGGOS in summer 2003. The proposal
will be made at the Nice Executive Committee meeting.
Concrete Action Items:
References
G. Beutler, F. Brunner, J.
Dickey, M. Feissel, R. Forsberg, I.I. Mueller, R. Rummel, F. Sanso, and K.P.
Schwarz: The IAG Review 2000-2001: Executive Summary. International Association
of Geodesy Symposia, Volume 125, pp. 603-608, Springer-Verlag 2002.
R. Rummel, H. Drewes, G.
BeutlerL Integrated Global Geodetic Observing System (IGGOS): A Candidate IAG
Project. International Association of Geodesy Symposia, Volume 125, pp.
609-614, Springer-Verlag 2002.
G. Beutler, H. Drewes, Ch. Reigber, R. Rummel: Proposal
to Establish the Integrated Global Geodetic Observing System (IGGOS) as IAG’s
First Project. IAG Executive Committee, Spring 2003.