GGOS
Terms of Reference2023

September 2023

Imprint
Publisher

GGOS - Global Geodetic Observing Systemof the International Association of Geodesy (IAG)
September 2023

Contact Information
GGOS Coordinating Office
Federal Office of Metrology and Surveying
Schiffamtsgasse 1-3, 1020 Vienna, Austria
www.ggos.org co@ggos.org© 2023 GGOSGlobal Geodetic Observing System (GGOS)
of the International Association of Geodesy (IAG)

Global Geodetic Observing System (GGOS) of theInternational Association of Geodesy (IAG)
Terms of Reference 2023

Preface
The proposal for the Global Geodetic Observing System (GGOS) was developedby the GGOS planning group between 2001 and 2003 according to the Bylawsof the International Association of Geodesy (IAG). The proposal was acceptedby the IAG Executive Committee and the IAG Council at their meetings during
the XXIII IUGG General Assembly in Sapporo in July 2003. GGOS was endorsedby the IUGG through Resolution No. 3 at the same General Assembly.
Changes in the IAG Bylaws in 2007 resulted in GGOS being recognized as anintegral component of IAG along with Services and Commissions. Thistransformed the status of GGOS from that of an IAG Project to an IAG
component. Specific to GGOS are IAG Bylaw numbers 1(d) and 15.
The Terms of Reference of GGOS are regularly updated according to changes in
the Statutes and Bylaws of its parent organization, the IAG, new strategic
challenges for GGOS, achieved objectives, and organizational changes to meet
new user needs or to be in line with global initiatives in geodesy matters.
Previous versions of the GGOS Terms of Reference are available in the
Geodesist’s Handbooks of 2008 (https://doi.org/10.1007/s00190-008-0259-0,
pages 826 – 829), 2012 (https://doi.org/10.1007/s00190-012-0584-1, pages
915 – 926), 2016 (https://doi.org/10.1007/s00190-016-0948-z, pages 1079 –1094), and 2020 (https://doi.org/10.1007/s00190-020-01434-z, pages 197 –220).
The Terms of Reference presented in this document introduce some minorchanges to be consistent with the recent changes to the IAG Statutes andBylaws and to update the structure of GGOS. Changes to the GGOS structure
include, among others, the merging of the former GGOS Consortium and GGOS
Coordinating Board into the new GGOS Governing Board and the increasing of
the number of voting members. This helps to streamline decision making within
GGOS and enhances the involvement of all IAG components in the governanceof GGOS. The new structure of GGOS was endorsed by the IAG Executive
Committee on April 26, 2023 and approved by the former GGOS Coordinating
Board on May 30, 2023.
These Terms of Reference were approved by the former GGOS Coordinating
Board on June 30, 2023 and by the IAG Executive Committee on September 5,
2023.

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Part A: GGOS Background
GGOS,
the Global
Geodetic
Observing
System of theInternational
Association of
Geodesy

The parent organization of GGOS is the IAG. GGOS was established with themain objective of integrating and optimizing data analysis resources,
procedures and dissemination of results performed by the different IAG
components, namely the IAG Services, Commissions, Inter-Commission
Committees (ICC) and dedicated Projects. Motivation for the establishment of
GGOS as well as its main goals and challenges were documented by the IAG
science community in 2009 in The Global Geodetic Observing System: Meeting
the requirements of a global society on a changing planet in 20201.

Structure of the International Association of Geodesy
Essentially, GGOS works with the IAG Services to provide unique, mutuallyconsistent, and easily accessible geodetic products (including the geodetic
reference frames and the gravity field models) and the relevant geodetic
constants for science and society. GGOS works in concert with Commissions,
ICCs and dedicated projects concerning new developments, and it keeps all IAG
components informed of the work in GGOS. This interaction is essential tounderstand the complexity of the Earth system, and advance geodetic
knowledge as well as technology development. The societal benefit ofintegrated, consistent and high quality geodetic products is wide reaching,including improved navigation systems, better understanding of climate andenvironmental change, reliable Earth surface deformation modelling, precise
monitoring of mass transport within the Earth’s system, accurately determiningchanges in the rotation of the Earth, etc.
In order for GGOS to interact effectively with the other IAG components, all IAG
components have representatives in the various organizational elements of
GGOS (see Part C). Each IAG Service, Commission, ICC and Project has one
representative on the GGOS Governing Board. The Commissions, ICCs andProjects have two representatives in the GGOS Science Panel. Each IAG Service
1 Plag H.-P. and Pearlman M. (Eds.) Global Geodetic Observing System: Meeting the Requirements of a Global Society on a

Changing Planet in 2020, Springer Berlin, Heidelberg, https://doi.org/10.1007/978-3-642-02687-4.
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has up to two representatives in each GGOS Bureau (Bureau of Products andStandards and Bureau of Networks and Observations). IAG Services,
Commissions, ICCs and Projects participate in the various Focus Areas,
Committees and Working Groups established within GGOS according to theirareas of interest and objectives.

GGOS Vision Advancing our understanding of the dynamic Earth system by quantifying ourplanet’s changes in space and time.

GGOS Mission We live on a dynamic planet in permanent motion that requires long-term
continuous quantification of its changes in a truly stable frame of reference,
everywhere on or close to the Earth surface, at any time, and at high spatial
resolution. This ambitious program requires a strong cooperation among thegeodetic, geodynamic and geophysical communities, and to external
stakeholders. GGOS endeavours to provide this integration at the highest level,in service to the scientific community and society as a whole.

GGOS inInternational andInterdisciplinary
Contexts

A key objective of GGOS is to increase the international and interdisciplinary
visibility of the IAG and to engage with a diverse and growing range ofstakeholders to raise awareness of the benefits of geodesy to science andsociety. In particular, GGOS contributes to two main initiatives: the scientificmonitoring of global change, framed by the Group on Earth Observations(GEO), and to address global challenges related to the production and use of
geospatial information, framed by the United Nations Committee of Experts on
Global Geospatial Information Management (UN-GGIM).
In the context of GEO, GGOS is the IAG’s contribution to the Global Earth
Observation System of Systems (GEOSS). GEOSS is a set of coordinated,
independent Earth observation, information and processing systems thatinteract and provide access to diverse information for a wide range of users inboth the public and private sectors. GGOS seeks the active participation of thegeodesy community in current GEO flagships, programmes and initiatives.
In the context of UN-GGIM, GGOS contributes to sustaining the UN Global
Geodetic Reference Frame (UN-GGRF) through science-policy networking incollaboration with the UN-GGIM’s Subcommittee on Geodesy (SCoG) and therecently established UN Global Geodetic Centre of Excellence (UN-GGCE). The
UN-SCoG provides an intergovernmental forum for cooperation and exchangeof dialogue in support of the UN-GGCE, whose main task is to coordinate thedevelopment of a permanent, globally government-supported geodetic
infrastructure as a cornerstone for the maintenance, sustainability andenhancement of the UN-GGRF. GGOS seeks a symbiosis between the scientificexpertise of the IAG and the political framework of the UN-GGCE in order to
optimize resources for an effective improvement of the global geodetic
infrastructure.
GGOS also represents the IAG on the Committee on Earth Observation
Satellites (CEOS). CEOS is a consortium of 61 agencies operating 172 satellites
worldwide working together to ensure international coordination of civil,
space-based, Earth observation programs for the benefit of all.

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Part B: GGOS Strategic Direction
Overarching GGOS Goals, Objectives, and Outcomes are built around four strategic priorities
Strategic that were first communicated in 2011 and then reiterated in the 2014 Strategic
Priorities of Plan, and continue to be relevant to the activities and future efforts of GGOS.
GGOS
The strategic priorities of GGOS are:▪

Geodetic Information and Expertise
Development and maintenance of organizational intangible assets,
including geodetic information, expertise, and capacity building.

▪

Global Geodetic Infrastructure
Identification of gaps in the geodetic infrastructure and advocacy formodernization, extension and maintenance of the existing global
geodetic infrastructure.

▪

Standardization, Integration and Optimization
Interaction with all IAG components to provide unique standards andmutually consistent, highly reliable, and easily accessible geodetic
products.
Communication, Education, and Outreach
Public relations, marketing, outreach, and engagement to ensure along-term sustainable geodetic enterprise.

▪

Long-Term Goals
and Key
Objectives of
GGOS

GGOS aims to reinforce its role as a collaboration hub in the IAG, working as anobserving system in support of sustainable geodesy by advocating andintegrating diverse geodetic technologies and applications. In the focus of
GGOS are:▪

The observations needed to monitor, map, and understand changes inthe Earth’s shape, rotation, and mass distribution.

▪

The global geodetic frame of reference that is the fundamental
backbone for measuring and consistently interpreting key globalchange processes and for many other scientific and societal
applications.

▪

The benefit of science and society by providing the foundation uponwhich advances in Earth and planetary system science and applications
are built.

Strategic Plan of GGOS revises and updates its strategic goals and supportive objectives regularly
GGOS to meet emerging needs in geodetic matters. Based on extensive community
surveys, GGOS designs updated versions of its Strategic Plan, highlighting crosscutting community needs that each strategic goal shall endeavour to address.
Guided by the strategic goals, the community needs are elements of a holistic
effort to support the geodetic community and advance the recognition and use
of geodesy for public benefit through innovation, advocacy, communication,and integration. The Strategic Plan is then complemented by an associated

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Implementation Plan containing the actions designed to achieve GGOS goals
and objectives. The core of the Implementation Plan is to identify, assign,
execute, and monitor the progress of these actions, which can be multi-year
efforts depending on their nature. Detailed version of the current GGOS
Strategic Plan and the associated Implementation Plan are available athttps://ggos.org/.

Part C: GGOS Structure
Overview of Key The organizational structure of GGOS consists of the following key elements:
GGOS Elements
GGOS Governing Board—is the central oversight and decision-making bodyof GGOS and the collective voice for all GGOS matters.
GGOS Executive Committee—serves under the direction of the GGOS
Governing Board to accomplish day-to‐day activities of GGOS.
GGOS Science Panel—provides advice and recommendations to the GGOS
Governing Board and other GGOS elements on scientific aspects
relevant to GGOS.
GGOS Coordinating Office—serves as the Secretariat of GGOS, coordinates
the administrative work in support of the various GGOS structuralelements, and is responsible for outreach and communications.
GGOS Bureau of Products and Standards—tracks, reviews, examines,
evaluates all current standards, constants, resolutions and products
adopted by IAG or its components and recommends their further use
or proposes the necessary updates.
GGOS Bureau of Networks and Observations—develops a strategy todesign, integrate and maintain the fundamental geodetic
infrastructure including communication and data flow; monitors thestatus of the networks and advocates for implementation of core andother co-located network sites and improved network performance.
GGOS Affiliates—are national or regional organizations that coordinate
geodetic activities in that country or region. GGOS Affiliates allow
increased participation in GGOS, especially by organizations in underrepresented areas of Africa, Asia-Pacific, and South and Central
America.
GGOS Committees, Working Groups and Focus Areas—address overarchingissues common to several or all IAG components, and are a mechanism
to bring the various activities of the Services, Commissions, InterCommission Committees and Projects together, or to link GGOS toexternal organizations. Focus Areas are cross-disciplinary and address
specific topics where GGOS contributors work together to address
broader and critical issues.

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GGOS organisational elements

GGOS Function
Governing
The Governing Board is responsible for governance, strategic policy andBoard
direction.
Membership
The membership of the GGOS Governing Board consists of delegatesappointed by the other IAG components, the officers chairing the different
GGOS components (see following sections), elected members-at-large andappointed members. Each primary delegate may nominate an alternate totemporarily assume responsibilities (i.e. voting) if the primary delegate isunable to attend a meeting. One person may not hold two voting positions
on the GGOS Governing Board. The membership of the GGOS Governing
Board follows the four-year term used in the IAG. Renewal of thismembership takes place during or shortly after the IUGG General
Assemblies (see IAG Bylaws for more details).
Appointment and Election of Governing Board Members
Representatives of IAG Services, Commissions, ICCs and Projects
Each IAG Service, Commission, ICC and Project is invited to nominate
one delegate to the GGOS Governing Board. Delegates appointed to
the Governing Board as representatives of the IAG Services,
Commissions, ICCs or Projects must be active members of thosecomponents. After a four-year term, it is at the discretion of each IAG
component to renew its representation with the same delegate or tonominate a different colleague. In the event that a representative isunable to participate in the duties of the GGOS Governing Board (dueto illness, retirement, change of affiliation, etc.), the GGOS President
shall request a new appointment (replacement) from the respective
IAG component.
Members-at-Large
Members-at-large are invited to serve on the GGOS Governing Board
to provide balanced representation of geographic regions or unique
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GGOS
GoverningBoardcapabilities. The GGOS President, with the assistance of the GGOS
Coordinating Office, shall appoint an Election Committee to organize
the election process. This process includes issuing a call-forparticipation to identify possible candidates, ensuring the availability of
the nominated candidates, and consolidating a final slate of membersat-large candidates. The Election Committee shall then present thisfinal slate to the GGOS Governing Board for a vote. In the event that amember-at-large is unable to participate in the duties of the GGOS
Governing Board (due to illness, retirement, change of affiliation, etc.),
the GGOS President, with the assistance of the GGOS Coordinating
Office, shall submit a list of at least two candidates for replacement to
the GGOS Governing Board.
Appointed Members
After the election of the members-at-large, the GGOS Executive
Committee can nominate up to two additional members to balance
research areas or geographic regions not covered by the members-atlarge. All candidates must then be approved by the Governing Board.
In the event that an appointed member is unable to participate in theduties of the GGOS Governing Board (due to illness, retirement, change
of affiliation, etc.), the GGOS Executive Committee can nominate
another colleague to serve in his/her place.
GGOS Officers
The GGOS President, Vice President, Immediate Past President,
Coordinating Office Director, External Relations Manager, GGOS
Bureau Directors, and chairs of the Focus Areas, Committees andWorking Groups established within each GGOS component are exofficio members of the GGOS Governing Board during their terms ofoffice. See below for details.
Representatives of the GGOS Affiliates
Each GGOS Affiliate is invited to nominate one delegate to the GGOS
Governing Board. Delegates appointed to the Governing Board as
representatives of the GGOS Affiliates must be active members of therespective Affiliates. After a four-year term, it is at the discretion ofeach GGOS Affiliate to renew its representation with the same delegate
or to nominate a different colleague. In the event that a representativeis unable to participate in the duties of the GGOS Governing Board (dueto illness, retirement, change of affiliation, etc.), the GGOS President
shall request a new appointment (replacement) from the respective
GGOS Affiliate.
VotingDecisions shall be made by consensus whenever possible. Decisions
requiring a vote shall be made by a simple majority of the votes cast. The
quorum for valid vote is fifty percent of the voting Governing Board
members. Voting may be conducted in-person at meetings or byappropriate electronic means at the discretion of the GGOS Executive
Committee.
Meetings
The Governing Board shall meet at least once a year, but twice a year ispreferred. Observers may attend the Governing Board meetings at the
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GGOS
Governing
Board

discretion of the GGOS President. Governing Board meetings shall be
convened by the GGOS President with the support of the GGOS
Coordinating Office.
Membership of the GGOS Governing Board (as of September 2023)

GGOS The GGOS President is elected by the IAG Executive Committee from a slate ofPresident nominations submitted and approved by the GGOS Governing Board. The
President is appointed for a period of four years, renewable once. The GGOS
President is the primary spokesperson and representative of GGOS to the IAG
and external organizations. The GGOS President shall provide overall leadershipfor GGOS. The GGOS President shall preside at meetings of the GGOS Governing
Board and GGOS Executive Committee and at the GGOS Days. Upon completionof his/her term as GGOS President, he/she shall serve Immediate Past President
for the next term.

GGOS The Vice President of GGOS is nominated by the GGOS President and thenVice President approved by the GGOS Governing Board. The GGOS Vice President shall assist
the GGOS President and act as the President in the absence of the President orwhen a motion involving the President is under consideration.

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GGOS Function
Executive
The GGOS Executive Committee is responsible for the administration of theCommittee
affairs of GGOS in accordance with these Terms of Reference and thedecisions of the GGOS Governing Board.
Membership
The GGOS Executive Committee consists of the following members:

Appointment and Election of Executive Committee Members
The GGOS President, Vice President, Immediate Past President,
Coordinating Office Director, External Relations Manager and the Directorsof the GGOS Bureaus shall be members of the GGOS Executive Committees
during their terms of office.
The Governing Board members should elect two representatives to the
GGOS Executive Committee. These representatives must be voting
members of the GGOS Governing Board and shall serve on the GGOS
Executive Committee for a term of four years.
Meetings
The GGOS Executive Committee shall hold monthly video or
teleconferences and shall meet in-person during the GGOS Governing
Board meetings. GGOS Executive Committee meetings shall be convenedby the GGOS President with the support of the GGOS Coordinating Office.
The Immediate Past President of GGOS, the Chair of the GGOS Science
Panel, and the President of the IAG or his/her designated representative
shall be permanently invited guests at meetings of the GGOS Executive
Committee. Other observers may be invited to attend these meetings (orteleconferences) as needed.

GGOS Function
Science
The GGOS Science Panel is an independent and multidisciplinary advisoryPanelboard that provides scientific support and guidance to the GGOS steeringand coordination entities as requested. This support includes in particular,
assistance in revising and updating the content of the GGOS 2020 book and

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organizing relevant scientific sessions at conferences, workshops, andother events.
Membership
The members of the GGOS Science Panel are delegates from the IAG
Commissions, ICCs and Projects and from the GGOS Focus Areas. Membersat-large may also be nominated when specific scientific topics not coveredby the IAG are to be discussed. Membership of the GGOS Science Panelfollows the usual four-year term. Renewal of this membership takes place
during the IUGG General Assemblies.
Appointment and Election of the Science Panel Members
Each IAG Commission, ICC and Project is invited to nominate two delegatesto the GGOS Science Panel. Each GGOS Focus Area is invited to nominate
one delegate to the GGOS Science Panel. Delegates appointed to the GGOS
Science Panel as representatives of the IAG Commissions, ICCs, Projects or
GGOS Focus Areas must be internationally recognized scientists who areexperts in the topics they represent. All nominated delegates must be
approved by the GGOS Governing Board. The GGOS Governing Board may
appoint additional at-large members to the GGOS Science Panel to coverscientific topics not covered by the IAG.
After a four-year term, it is at the discretion of each IAG component and
GGOS Focus Area to renew its representation with the same delegate(s) or
to nominate a different colleague(s). In the event that a representative isunable to participate in the duties of the GGOS Science Panel (due to illness,retirement, change of affiliation, etc.), the GGOS President, with thesupport of the GGOS Coordinating Office, shall request a new appointment(replacement) from the respective IAG component or Focus Area.
The immediate past Chair of the GGOS Science Panel is a Member of the
GGOS Science Panel.
The GGOS Science Panel elects its own Chair, who is approved by the GGOS
Governing Board. The GGOS Science Panel Chair is appointed for a periodof four years, renewable once.

GGOS
Committees,
Working Groups
and Focus Areas

The various GGOS structural elements may propose the establishment ofCommittees and Working Groups as needed, in accordance with the IAG
Bylaws. The proposed Committees and Working Groups must be approved by
the GGOS Governing Board. Working Groups shall be established for a periodof four years, Committees for a longer indefinite period. The GGOS Governing
Board appoints their chairs and prepare and approve their charters.
GGOS Focus Areas are cross‐disciplinary and are intended to address gaps andneeded future products. The GGOS Governing Board approves the GGOS Focus
Areas and appoints their leaders. GGOS Focus Areas outline their charter andpropose plans for the work they will undertake.

GGOS The GGOS Coordinating Office serves as the Secretariat of GGOS, coordinates
Coordinating the administrative work in support of the various GGOS structural elements,
Office and is responsible for outreach and communications. The GGOS Coordinating

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Office ensures information flow, maintains documentation of the GGOS
activities, and manages specific assistance functions that enhance theadministrative coordination across all areas of GGOS, including inter‐services
coordination and support for meeting and workshops. The GGOS Coordinating
Office, in its long‐term coordination role, ensures that the GGOS components
contribute to GGOS in a consistent and continuous manner. The GGOS
Coordination Office also maintains, manages, and coordinates the GGOS web
and social media presence.
The position of Manager of External Relations resides within the GGOS
Coordinating Office. The Manager of External Relations coordinates, inconsultation with the GGOS President, GGOS engagement with externalorganizations such as the Group on Earth Observations (GEO), the Committee
on Earth Observation Satellites (CEOS), the International Science Council (ISC)
World Data System (WDS), the Federation of Surveyors (FIG), the UN Global
Geospatial Information Management (UN-GGIM) Subcommittee on Geodesy(SCoG), and the UN Global Geodetic Centre of Excellence (UN-GGCE). The GGOS
Governing Board elects the Manager of External Relations by vote.

GGOS Bureau of The GGOS Bureau of Products and Standards monitors the strict observance ofProducts and adopted resolutions, geodetic standards, standardized units, fundamental
Standards physical constants and conventions in all official products provided by thegeodetic community. It reviews, examines and evaluates all current standards,
constants, resolutions and conventions related to geodesy adopted byinternational organizations such as ISO (International Organization forStandardization), IAU (International Astronomical Union), IUGG, IAG and theircomponents, and recommends their further use or proposes the necessary
updates. It identifies possible gaps in standards and products, and initiates
steps to fill them with, e.g., through resolutions of the IUGG and/or IAG
Councils.

GGOS Bureau of The GGOS Bureau of Networks and Observations develops a strategy to
Networks and sustainably design, integrate, and maintain the fundamental geodetic
Observations infrastructure to meet the long-term (10–20 years) requirements identified by
the GGOS Science Panel. The Bureau advocates for the implementation of coreand other co-located network sites to satisfy GGOS requirements, monitors thepresent state of the networks and projects future states, and supports andencourages infrastructure critical for the development of data products
essential to GGOS. Primary emphasis must be placed on sustaining theinfrastructure needed to maintain the evolving global reference frames, while
ensuring broader support for the scientific applications of the data collected.
The coordination and implementation of the GGOS co-located station network
is a major focus of the Bureau.

GGOS Affiliates A GGOS Affiliate is a national or regional organization that coordinates geodetic
activities in that country or region. GGOS Affiliates provide a forum for multitechnique, space geodetic discussions, work to improve the quality of space
geodetic observations, and encourage cooperation among the various agencies
in that country or region that own, operate, and maintain the space geodetic

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infrastructure there. To become a GGOS Affiliate, interested organizations
submit an application to GGOS, which is approved by the GGOS Governing
Board by vote.

Part D: Modification and Approval of Revisions
Changes to the Amendments to these Terms of Reference shall be approved by at least a
GGOS Terms of simple majority of the votes cast by the GGOS Governing Board. The amended
Reference Terms of Reference shall then be submitted to the IAG Executive Committee
for approval at its next meeting. Amendments shall take effect at the end of
the IAG Executive Committee meeting.
The rules contained in the current edition of Robert’s Rules of Order Newly
Revised2 shall govern GGOS in all cases to which they are applicable and inwhich they are not inconsistent with these Terms of Reference or any special
rules that may be adopted by the GGOS Governing Board.

Approval of the These Terms of Reference were approved by the former GGOS Coordinating
Terms of Board on June 30, 2023 and by the IAG Executive Committee on September 5,
Reference 2023.

2 https://robertsrules.com/

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