Bureau of Networks and Observations Implementation Plan

Bureau of Networks and Observations
Implementation Plan for 2020 – 2022
Version 7a

1.0 IMPLEMENTATION OVERVIEW
1.1

Introduction

The Bureau of Networks and Observations (BN&O) works with the IAG Services toaddress requirements set by the GGOS Science Committee. The Bureau focuses
primarily on the infrastructure needed to maintain the International Terrestrial
Reference Frame (ITRF) and the International Celestial Reference Frame (ICRF), in asustainable way, over the long-term (~20 years), while at the same time, addressing
other scientific applications identified as important to GGOS and the IAG. In particular,
BN&O supports the current efforts oriented to the establishment of the International
Height Reference Frame (IHRF) and the International Gravity Reference Frame (IGRF).
The infrastructure currently includes the space geodetic network of co-locatedinstruments (VLBI, SLR, GNSS, DORIS) and other instruments or observations (gravity
field measurements, reference clocks, tide gauges, etc.) that may be added to enhancethe data products. In the near future, the description of the infrastructure will be
extended to include core stations of the IHRF and IGRF.
Standing Committees and Joint Working Groups including the Standing Committee on
Performance Simulations & Architectural Trade-Offs (PLATO); the Standing Committee on
Satellite Missions, the IERS Working Group on Survey Ties and Co-location, and theStanding Committee on Data and Information are included in the Bureau in recognitionof their synergistic role with Bureau activities The Bureau advocates for implementationof core and co-location network sites to satisfy GGOS requirements, monitors the present
state of the networks and projects future status, and supports and encourages
maintenance and improvement in the infrastructure critical for the development of data
products essential to GGOS.
The Bureau, originally established as the Bureau of Networks and Communications in2003), works to exploit synergistic opportunities to better integrate or co-locate with
the infrastructure and communications networks of the many other Earth observation
disciplines organized under GEOSS, and to work with current and perspective
organization to help improve the network capability. Aside from the geometric services
the IGS (Dow, J. et al., 2009), the IVS (Schuh, H. et al, 2012; Behrend, D., 2013), the ILRS
(Pearlman, M. et al., 2002), the IDS (Willis, P. et al., 2016); the IGFS (Wziontek, H. et al.
2011) and the PSMSL (Simon, J. et al, 2013) are now integral components of the Bureau.

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Efforts are underway by GGOS to integrate these other services and techniques into the
GGOS network to enhance geodetic products.
The Bureau of Networks and Observations provides a means of greater coordination
among the services and the supporting entities and provides a conduit for discussion
and information to GGOS on policy and decision-making. The role of the Bureau will bebased on the requirements set by GGOS and the IAG and its integration into the GGRF.

1.2

Goals and Objectives

The primary goal of the Bureau is to work with the Services and the funding agencies toadvocate for the enhanced networks of sufficient global distribution and measurement
capability to address the Earth science and societal benefit requirements set by GGOS.
Satisfying this goal requires development of a strategy to design, integrate, implement
and maintain the core geodetic network of co-located instruments and supporting
infrastructure in a sustainable way. At the base of GGOS are the sensors and theobservatories situated around the world providing the timely, precise, and fundamental
data essential for creating geodetic products. Primary emphasis must be placed onsustaining the infrastructure needed to maintain the evolving terrestrial and celestialreference frames, while at the same time ensuring the broader support of the scientificapplications of the collected data. Synergistic opportunities should be exploited to better
integrate and co-locate with the infrastructure and communications networks of themany other Earth observation disciplines organized under GEOSS. Furthermore,
additional measurements, such as those from the gravity field and from tide gauge
networks, must be included.
Although the Bureau will get its primary direction from the GGOS Science Council and the
Executive Committee, the Bureau and the services must also recognize scientific andsocietal benefits and important synergies that will accrue through connection with theother entities.
The Bureau will work with the UN GGIM Subcommittee on Geodesy in its mission todevelop a sustainable Global Geodetic Reference Frame (GGRF). The documents listed
below give an overview of the goals of the Committee.
•
•
•

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Position Paper on Sustaining the Global Geodetic Reference Frame (Committee
on Geodesy)
Concept Paper on Establishing a Global Centre of Excellence (Committee on
Geodesy)
Global Geodetic Centre of Excellence (GGCE) for the United Nations Global
Geospatial Information Management – IN-GGIM. (Federal Government ofGermany)

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From the Subcommittee work packages, the Bureau sees its main role involved in Sub ID
INF.2, with particular stress on “Communicate plans for IAG services to be used tomodernize/improve geodetic infrastructure”, and advocate for the implementation of the
improved infrastructure (network).
1. This activity should start with the performance of the current network stations
and their contribution to the data products. The anticipated capability from new
stations underway and planned, and from current stations being upgraded would
be added. Then using simulation techniques, the added capability needed to meet
the ITRF requirement would be estimated and commensurate enhanced network
configurations studied, along with other steps that would enhance the projectedcapability (Co-location in space, separated stations connected by redundant GNSS
measurements from a continuously operating GNSS network, etc.). Generallocation of stations that will be required have been advanced in many publications
already (e.g. Core Sites in Africa, Latin America, and Oceana). We are hoping that
the UN GGIM Committee on Geodesy will help us make proper inroads.
The Roles of the Bureau are to:
1. In collaboration with the UN GGIM and the Services formulate a network
development plan to address the GGOS requirements;
2. Advocate for the expansion and upgrade of the space geodesy network for the
maintenance and improvement of the reference frame and other GGOS
priorities; Main focus will be on the Reference Frame; but the other applications
need to be accommodated;
3. Encourage partnerships to build and upgrade network infrastructure
4. Organize and expand the GGOS affiliated network;
5. Monitor network status; project network evolution based on input from theServices and the sponsors; estimate performance capability 5 and 10 years
ahead;
6. Conduct simulation studies and analyses to assess impact on reference frame
products of: network configuration, system performance, technique andtechnology mix, co-location conditions, site ties, and network trade of options(PLATO);
7. Develop Metadata Systems for a wide range of users including GGOS; near term
strategy for data products (Carey Noll at GSFC) and a more comprehensive
longer-term plan for an all-inclusive system (Committee on Data andInformation);
8. Enhance and improve knowledge of local tie surveys through applied fieldpractice, research, and dissemination of materials developed (IAG Joint Working
Group (w/ IERS) 1.2.1)
9. Advocate, coordinate, and exchange information with satellite missions as partof the GGOS space infrastructure, for a better ground-based network responseto mission requirements and space-segment adequacy for the realization of the
GGOS goals (Committee on Missions)

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10. Provide the opportunity for representatives from the Services and the Standing
Committees to meet and share progress and plans; discuss issues of common
interest; meetings at EGU, AGU, GGOS Days, etc.;
11. Talks and posters on the Bureau at EGU, AGU, JPGU-AGU, AOGS meetings, etc.;
12. Letters/documentation to support stations, current/ new missions, and analysis
centers;

1.3 Bureau of Networks and Observations Authority, Governance
Structure, Management Structure, and Implementation Approach
1.3.1 Authority
The Bureau is a “consortium of the willing”; its only authority is that recognized by its
members.
The Bureau is a consortium of representatives of the IAG Services, Commissions, Standing
Committees and Participating Working Groups with a common goal of guiding the design,evolution and implementation of the observation-gathering networks. The Bureau will
maintain a liaison with the GGOS Focus Areas and include them in Bureau activities. The
Bureau is self-managed, following the guidelines, policies, and procedures put in place by
the GGOS Coordinating Board. The Bureau works with the services and committees andworking groups to formulate their tasks that will support these policies and procedures,
implementing reporting procedures/plans in a timely yet reasonable manner to havedirect impact on the Bureau goals. The Bureau is essentially a “consortium of the willing”
benefitting from members’ implementation plans to satisfy programs enacted by theirparent organizations, which are likely, a component of GGOS. In many cases the Bureau
task will be advocating, promoting, and/or measuring progress.
Elements within the Bureau will need to interact with entities outside the Bureau; someof these are spelled out in the working group briefs in Appendix 4.1. If direct contact does
not prove fruitful then the Bureau and its committees will work through the Coordinating
Board (CB).
1.3.2 Membership
GGOS and the Bureau will benefit significantly from expanding its membership bothtechnically and geographically. In particular, we encourage the promotion of GGOS
Regional Affiliates as our Japanese colleagues have done, and by expanding participating
partnerships.

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Table 1.2-1: Bureau of Networks and Observations Goals and Objectives Mapping. The table identifies the primary (✓✓) and secondary (✓) Goals andObjectives that the Bureau of Networks and Observations will be supporting to meet the outcomes stated in the GGOS strategic pan. Primary goals andobjectives are those that are aligned with the charter of the GGOS Entity in question and are not likely to be realized without its involvement. Secondary
goals and objectives are those that the given GGOS Entity can support as part of its charter.

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The focus of the Bureau has been primarily on the geodetic networks and the functions
that support them, and in some cases the disposition of their products. The IGFS has beenworking with the Bureau to define measurement and station configuration requirements
for the IHRF and the IGRF. It is assumed that best use will be made of the network coreand co-location sites. The PSMSL has been working with the IGS on the co-location of IGS
instruments with operating tide gauges; discussions are also underway with DORIS. Oncethese are formulated, the Bureau will work with the Bureau of Products and Standards(BP&S), the themes, and focus areas to identify and quantify measurement requirements
and help integrate these requirements into the network. A draft of these requirements
will be included in the next version of the CORE and Co-location Site Requirements
Document. It is assumed that the best use of the network Core and co-locations sits.
1.3.2 Governance Structure
Not Applicable
1.3.3 Management Structure
ALLOCATION AND DISTRIBUTION OF RESOURCES
All resources to support the Bureau will be provided by its members; we do not anticipate
that any external support funds will be available. As such, the resources required to run
the Bureau will be the personnel, travel, and other services provided by its participants
through their support agencies/institutions. See Table 1.3-1.
The IGS, IVS, ILRS, IDS, IGFS, PSMSL, and the IERS are represented in the Bureau. The IAG
services and the standing committees chose their member representatives to the Bureau.
Some rules may be formulated for succession.
The Standing Committees and Working Groups within the Bureau have formulated work
plans in concert with the Bureau that address key issues for GGOS.

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Table 1.3-1: BN&O Resources.
Position

Resource

EntityContributing

DirectorMike Pearlman

CfA (USA)

Deputy Director

TBD

TBD

Secretary

TBD

TBD

Analysis Specialist

Erricos Pavlis

UMBC (USA)IVS Service Representatives

Hayo Hase
Dirk Behrend

BKG (Germany)
NASA (USA)ILRS Service Representatives

Toshi Otsubo
Jean-Marie Torre

HIT-U(Japan)
OCA (France)

IGS Service Representatives

Allison Craddock
Michael Moore

JPL (USA)
GA (Australia)

IDS Service Representatives

Jérôme Saunier
Guilhem Moreaux

IGN (France)
CLS France)

IGFS Service Representatives

Riccardo Barzaghi
George Vergos

PM (Italy)
UT (Greece)

PSMSL Service Representatives

Elizabeth Bradshaw
Lesley Rickards

BODC (UK)
BODC (UK)IERS Representatives

Ryan Hippenstiel

NOAA/NGSStanding Committee on Performance
Simulations & Architectural Trade-Offs(PLATO) – joint with IAG Commission 1

Daniela Thaller
Benjamin Maennel

BKG (Germany)
GFZ (Germany)

Standing Committee on Data and Information

Nicholas Brown
TBD

GA (Australia)
NASA (USA)Standing Committee on Satellite Missions

Roland Pail
C.K. Shum
Ryan Hippenstiel

TUM (Germany)
OSU (USA)NOAA (USA)IERS Working Group on Survey Ties and CoLocation

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Bureau of Networks and Observations Implementation PlanOVERSEEING AND COORDINATING THE DAY-TO-DAY OPERATIONSThe Bureau will work with each entity to develop and update a task plan with a projectedschedule.
The Bureau does not oversee or coordinate the day-to-day activities of the services. The
services are their own entities within the IAG, with representation in the Bureau who help
guide the Bureau in its fulfillment of GGOS requirements. Day-to-day activities within thepurview of the Bureau will be coordinated and overseen by the individual entities, withperiodic reviews by the Bureau, working with the entity and recommending remedialaction if necessary.
REPORTING OF TECHNICAL AND/OR SCIENTIFIC PROGRESS AGAINST SCHEDULE
All services and standing committee/working groups will give oral and/or written reports
periodically, as required, on progress, adherence to the task plan, forced deviations, andchanges in circumstances and plans. Committees and Working Groups will have theopportunity to give a report at the Bureau meetings to be held during EGU, AGU andpossible at a third opportunity at roughly mid-year (meeting or teleconference). All
entities must report at the Bureau meeting at EGU and must provide a written summary
report for the annual GGOS Days meeting. The Bureau will give summary reports at GGOS
meetings and on the BN&O webpage on the GGOS website https://ggos.org/
DESCRIBE ANY CONFIGURATION MANAGEMENT REQUIRED FOR MANAGEMENT
Each of the services and standing committee/working groups will establish a page or alink (to a page elsewhere) on the GGOS Bureau section of the GGOS website to archive
documents, and post plans and progress reports. The Bureau will provide summary
reports and estimates of impact on schedule.

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Table 1.3-2: Bureau of Networks and Observations Plan. The table identifies the communications requirements of the BN&O
Communication Type

PurposeMediumFrequency

Audience

Owner

Deliverables

GGOS BN&O report at the
GGOS EC meetings

Report in BN&O
status, progress,
issues, and action
itemsVideo conference or
teleconMonthly or as
decided by the EC

EC members

EC

Oral report

GGOS BN&O report at the
GGOS CB and Consortium
Meetings

Report in BN&O
status, progress, andissues; other reports
as requested by the CB

Face-to-face; may
include videoconferencing

Twice per year
(EGU, AGU);
additional
meetings asdecided by the CB

CB members andConsortium
Members

CB

BN&O Presentations material and othermaterial as requested by the CB andConsortium

Bureau and entity report at
GGOS Days

Report in BN&O andentity status, progress,
issues, and action
items

BN&O: Face-to-face
and written; Entity
Reports written

Annually

Invitees to GGOS
Days

EC

Written Bureau and Entity reports

Component Reports at the
GGOS BN&O Meetings;
Summary meeting Report

Bureau and entity
Status Review andissuesFace-to-Face; may
include videoconferencing

AGU, EGU and anyother time set by
the Bureau

Bureau members,
invitees, andinterested parties.

BN&O

Before: Agenda

BN&O Committee andParticipating Working Group
Meetings

Review progress andplan forward

Face to Face or
telecon as thediscretion of the entity

Annually of at thediscretion of theentityEntity members andinterested parties.

EntitySummary report and status of tasks

Focused meeting

Review status on
specific topics

Oral and written

At the discretionof the Bureau

Bureau and entity
members involved

BN&O and involved
entities

Oral and written report9

After: Presentation material posted on thewebsite; meeting notes; action items.

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1.3.4 Implementation Approach
The Bureau is a consortium of IAG service representatives and participating standing
committees/working groups. Two members of each Bureau entity are members of the
Bureau leadership; thus, each entity participates in the Bureau discussions. The Bureau
leadership will encourage members of each entity to attend and participate infunctions/meetings/workshops of other entities. This overall structure will be
implemented to provide close interaction among the entities to enhance crossfertilization and communication.
The Bureau will define the near- and long-term objectives to support GGOS goals.
The Bureau will coordinate closely with the Bureau of Products and Standards (BP&S) andlook to the BP&S, CB, and the EC for guidance in setting network requirements to address
new data products (themes, new focus areas, etc.) and to help the Bureau to formulate
its recommendations and options.
The Bureau and its services may interact with some or all of the agencies andorganizations that participate or will participate in the network or are key interface points
for the missions.
The Bureau does not capital decisions; in concert, the Services and the sponsors might
decide to make such decisions.

1.4

Stakeholder Definition

The network data are the basis for the development of the reference frame and many of theother data products that GGOS will facilitate. As such, GGOS is the main internal
stakeholder along with its internal entities the Bureau for Products and Standards, the
GGOS Portal, etc. See table 1.4-1 below
The data from the GGOS network are the basis for the reference frame, precision orbit
determination, precise station positioning, Earth rotation, and all of the other data
products to be formed, soon to include including gravity field and tide gauges. External
stakeholders will include the IAG services, IERS, and other scientific organizations andresearch institutions. It will include the broad range of the external data and data productusers including those working in navigation, civil engineering, surveying and mapping,precision timing applications, precision orbit determination, altimetry, monitoring
environment, and global change phenomena, etc. The BN&O will work with the IGFS and
the PSMSL/TIGA to advocate and promote network requirements of these communities
in support of GGOS-endorsed data products.
Stakeholder advocacy will be done at the services, the Bureaus, and GGOS level.

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The advocacy strategy seems to be a general GGOS task and shall be discussed within
GGOS.
Table 1.4-1 summarizes the advocacy strategy for the identified internal and external
stakeholders of the GGOS Bureau of Networks and Observations

2.0 GGOS BUREAU OF NETWORKS AND OBSERVATIONSBASELINES
PROJECT BASELINES CONSIST OF A SET OF REQUIREMENTS, A SCHEDULE, AND TECHNICAL OR SCIENTIFICCONTENT THAT FORMS THE FOUNDATION FOR THE GGOS ENTITY. BASELINES ALSO DETAIL THE EXECUTION
AND REPORTING THAT IS DONE AS PART OF GGOS GOVERNANCE PROCESSES AND PERFORMANCEASSESSMENTS.
The role of the Bureau is to advocate for the implementation of the ground network ofsufficient global distribution and measurement performance capability to address the
Earth science and societal benefit requirements set by GGOS. The Bureau will monitor
progress in the development of the networks, project network configuration based on
information provided by the Services, make recommendations based on analysis andsimulations, and distribute information to the community. Through the IERS Working
Group for Site Survey and Co-location it will work to improve site tie participation
including more frequent measurements and use of improved technology.
Through the Standing Committee on Data and Information the Bureau will work on thedevelopment and implementation of a GGOS metadata system.
The main focus of the Bureau is presently the reference frame and the evolution of the
global geodetic networks over time, but work is underway by Bureau and the IGFS and
the PSMSL to better define their role and position within the network, their data products
and the measurement requirements, and their contribution the reference frame. As the
network improves, there should be commensurate steps in the improvement of thereference frame. The Bureau will regularly report at the CB meeting and public meetings
on the evolution and plans for the network. Since the implementation of the full core sites
network capability will be very costly and take many years to achieve, near-term
compromises in network design and capability will be required in order to accommodate
realistic constraints. The Bureau will encourage the implementation and upgrade of colocation sites to augment the core network, and the inclusion of new techniques to allow
the network to support other data products.
As additional data products are developed and formalized, they will place additional
requirements on the network.

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Table 1.4-1: BN&O Stakeholders and Advocacy Strategies
STAKEHOLDERS

ADVOCACY STRATEGIESINTERNAL STAKEHOLDERS
GGOS Coordinating
Board, GGOS
Consortium, other
GGOS entities
including the GGOS
Bureau of Products
and Standards,
GGOS Portal,
Outreach, etc.

As the observing system of the IAG, GGOS serves a unique andcritically important combination of roles centering upon advocacy,
integration, and international relations. The IAG relies upon GGOS
and the GGOS BN&O to advocate for improvements in the groundbased geodetic infrastructure of GNSS and DORIS reference
stations, VLBI and SLR space geodetic stations, and gravity
observatories; it also supports the development of new satellite
missions for altimetry, gravity mapping, and Earth observation.
Overall, the Bureau promotes the importance of modern geodesy
for addressing the needs of science and society for stable reference
frames.
Advocacy strategies will include monthly telephone conferenceswith the Executive Committee and the Coordinating Office, biannual(or more frequent) meetings with the GGOS Coordinating Board andConsortium, and written reports as required to report progress andissues to help support the GGOS role in CEOS, GEO, GIAC, and UNGGIM and other international organizations

IAG Network, etc.
Services

GGOS BN&O works with the pertinent IAG services (at the moment
the IGS, IVS, ILRS, IDS, IGFS, and PSMSL) to advocate for andsupport the maintenance and upgrade of the network
infrastructure necessary for monitoring the Earth system and for
global change research.
Each of the pertinent services has representation in the BN&O.
Advocacy strategies will include frequent email and telephone
conferences with these service representatives, a minimum of twiceyearly Bureau meetings, as well as face-to-face meetings at major
conferences and/or workshops (approximately two to three times
per year) to discuss progress and issues.

IERS

The IERS develops the final reference frame products and thus
relies on the BN&O advocating role, coordination with the service
networks, and status and network capability projections activities.
The IERS Working Group on Survey Ties and Co-location supports
BN&O activities.
Advocacy strategies will include offering a position in the Bureau fora representative from the IERS, frequent email and telephone
conferences with IERS personnel, a minimum of twice-yearly Bureau
meetings, as well as face-to-face meetings at major conferences
and/or workshops (approximately two to three times per year) to
discuss progress and issues.

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EXTERNAL STAKEHOLDERSOUTSIDEORGANIZATIONS

2.1

Mapping agencies, space agencies, universities and researchgroups, etc. who are the owners of the geodetic
infrastructure

Requirements Baseline

LIST OR REFERENCE ANY REQUIREMENTS LEVIED ON THE BUREAU OF NETWORKS AND OBSERVATIONS THE BY
THE PARENT GGOS ENTITY, SUCH AS THE COORDINATING BOARD OR IAG; AND DISCUSS HOW THESE ARE
FLOWED DOWN TO LOWER LEVELS, SUCH AS GGOS OR IAG SERVICES WORKING GROUPS. SUMMARIZE
CORRESPONDING ALLOCATION PROCESSES. REFERENCE REQUIREMENTS DOCUMENTS USED BY THE BUREAU
OF NETWORKS AND OBSERVATIONS, E.G., GLOBAL OBSERVING SYSTEM, MEETING THE REQUIREMENTS OF A
GLOBAL SOCIETY... (SECTION 7.8, OPERATIONAL SPECIFICATIONS FOR GGOS). USE TABLE 2.1-1.
2.1.1 Geometric Space Geodesy Network
The reference frame baseline requirements are levied by the GGOS 2020 document. The
most stringent requirement comes from sea level rise:
•
•
•
•

•

Accuracy of 1 mm, and stability at 0.1 mm/yr., a factor of ~5 beyond current
capability;
Accessibility: 24 hours/day; worldwide;
The space segment is currently defined by LAGEOS-1 and -2, LARES, GNSS, DORIS,
and the quasars;
The ground segment is defined by a global distributed network of “modern
technology”, co-located SLR, VLBI, GNSS, DORIS stations and other ground-based
measurements (e.g., gravimeters, tide gauges, etc.), locally tied together withaccurate site ties;
A dense network of GNSS ground stations to distribute the reference frame
globally to the users;

Studies performed by Erricos Pavlis/UMBC have translated this requirement into a
network-size specification to define and maintain the reference frame;•••~ 32 globally distributed SLR, well positioned, new technology sites;~ 24 globally distributed VLBI, well positioned, new technology (VGOS) sites, colocated with SLR;
~ 16 of these co-location sites must track GNSS satellites with SLR to calibrate the
GNSS orbits, which are used to distribute the reference frame.

Recognizing that many sites will not be at ideal locations nor have ideal conditions, coresite deployment will occur over many years, and we will have a mix of new and legacy
technologies for many years; co-location sites (non-core sites) will continue to play a vitalrole in our data products and that the quality of our output will be the product of network
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Bureau of Networks and Observations Implementation Plancore sites, co-location sites, mix of technologies, adherence to proper operational andengineering procedures, and making best use of the data once it leaves the field.
The “heavy lifting” in network deployment and upgrade will be done by the National andResearch Institutes, Space Agencies, Universities, and other entities that provide thefunding and infrastructure. We expect that these entities will work with the Services andthe Bureau to take advantage of existing experience and expertise, and implement andupgrade to address IAG/GGOS requirements. The GGOS BN&O will advocate for
implementation of the global space geodesy network of sufficient capability to achieve
data products essential for GGOS and will provide a multi-technique community for theservices to work and plan together. The BN&O will monitor and project the status andevolution of the space geodesy network and project network performance capability tohelp guide the activities.
2.1.2 Global Gravity Reference Network
The gravity reference system in use is the International Gravity Standardization Net 1971 (IGSN71)(Morelli et al. 1974). It was stablished in the 1960s and 1970s by means of relative gravity
measurements based on a few absolute gravity stations and presents an uncertainty at the level of
10−6 m s−2 . This uncertainty level is insufficient to meet the requirements imposed by themeasurement accuracy of 5 to 10  10-8 m s-2 achievable by modern gravimeters and needed tomonitor and understand changes within the Earth System. In agreement with the IAG Resolution
No. 2 (2015) “Establishment of a Global Absolute Gravity Reference System” (Drewes et al.,2016), an essential task for the near future is the implementation of the International Gravity
Reference Frame (IGRF) as the realization of the International Gravity Reference System (IGRS),
see Wziontek et al., (2021). The IGRS is defined by the instantaneous acceleration of free-fall,
expressed in the International System of Units (SI) and a set of conventional corrections for timeinvariant and time-dependent components of gravity effects. The IGRF is given by a global set of
stations where reliable absolute gravity values with a relative accuracy of 10−8 and better areprovided. According to Wziontek et al., (2021), the main infrastructure of the IGRF is formed by:•••Reference stations to ensure a long-term stable absolute gravity reference. These stations
should be equipped with a continuously operating superconducting gravimeter in
combination with repeated absolute gravity observations or a continuously operating
absolute quantum gravimeter. If a continuous monitoring is not possible, repeatedabsolute gravity observations are needed. Stations of the International Geodynamics andEarth Tide Service (IGETS) (Boy et al. 2020) with long-term superconducting gravimeterrecords should become an essential part of the IGRF.
Comparison stations are reference stations with extended facilities to check thecompatibility of instruments, based either on continuous gravity monitoring or by
simultaneous measurements of at least two absolute gravimeters.
Core stations to ensure a link to the ITRF. They should be co-located with GGOS core sites
and further ITRF stations where at least one space geodetic technique is established. In
accordance with the GGOS requirements for core sites, it is recommended tocontinuously monitor temporal gravity variations and to repeat absolute gravity
observations at all GGOS core sites.

In order to guarantee sustainability of the gravity reference frame, all stations of the IGRF need to
be indicated by a permanent marker. All measurements at these stations should be documented and

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Bureau of Networks and Observations Implementation Planarchived in the IAG absolute gravity database (AGrav) operated by BGI (Bureau GravimétriqueInternational) and IGETS for static and time variable measurements, respectively. By this, the basis
for the further development of compatible infrastructure on the national level is provided.
Based on the advances and challenges described by Wziontek et al., (2021), the Bureau will workwith the IGFS, BGI, IGETS and the Bureau of Products and Standards to support theimplementation of the IGRF. An immediate step is to include the IGRF station requirements in the
documentation supporting the description of GGOS core sites (Appleby et al., 2015). The Bureau
will also support the activities of the working group “On the realization of the International Gravity
Reference Frame” chaired by H. Wziontek (Germany) and S. Bonvalot (France) for the term 2019
– 2023. The main objective of this working group is to promote the development of an adequate
infrastructure based on absolute gravity measurements supported by international and national
institutions, agencies and governmental bodies responsible for the geodetic reference frames.

2.1.3 Global Unified Physical Height Reference Network
The IAG introduced in 2015 the International Height Reference System (IHRS) as the conventionalreference for the determination of gravity field-related heights (see IAG Resolution No. 1 (2015)
in Drewes et al., 2016). The IHRS is defined in terms of potential quantities (Ihde et al., 2017): thevertical coordinates are geopotential numbers [C(P) = W0 − W(P)] referring to an equipotential
surface of Earth's gravity field realized by the IAG conventional value W0 = 62 636 853.4 m2s-2.
The spatial reference of the position P for the potential W(P) = W(X) is given by coordinates X,
dX/dt of the ITRS/ITRF. Thus, IHRS essentially materializes the combination of a geometriccomponent given by the coordinate vector X in the ITRS/ITRF and a physical component given by
the determination of potential values W at X. The realization of the IHRS is the International Height
Reference Frame (IHRF): a global reference network with regional and national densifications,whose geopotential numbers referring to the conventional potential W0 are known. To be inagreement with the certainty of the geometric coordinates, the accuracy of the IHRF geopotential
numbers and their variation with time should be at least 310-2 m2s-2 (equivalent to  3 mm inheight) and 310-3 m2s-2a-1 ( 0.3 mm a-1), respectively (see Ihde et al., 2017). However, thepresent achievable accuracy is some orders lower (from 1010-2 m2s-2 to 10010-2 m2s-2). In thisframe, current efforts concentrate on (Sánchez and Barzaghi, 2020): (i) designing a preliminaryreference network for the IHRF; (ii) studying strategies for the determination of precise potential
values W(P); and (iii) identifying/outlining the standards and conventions required to establish an
IHRF consistent with the IHRS definition.
According to Sánchez et al. (2021), the reference network for the IHRF should comprise (i) a core
network to ensure perdurability and long-term stability of the reference frame, and (ii) regional andnational densifications to provide local accessibility to the global IHRF. This reference network is
to be collocated with:• fundamental geodetic observatories (GGOS core sites) to allow the connection between
X, W, g and reference clocks,• continuously operating GNSS reference stations to detect deformations of the reference
frame,• geometric reference stations of different densification levels (ITRF and regional reference
frames) to provide access to the IHRF at regional and national levels,• reference tide gauges and national vertical networks to facilitate the vertical datum
unification within the IHRS, and• reference stations of the IGRS/IGRF (Wziontek et al., 2021).

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Bureau of Networks and Observations Implementation Plan
A main requirement is the availability of surface gravity data around the IHRF stations to ensure ahigh reliability in the determination of the reference potential values W(P). Currently, the GGOS
Focus Area Unified Height System and its working group “Implementation of the International
Height Reference Frame (IHRF)”, chaired by L. Sánchez (Germany) and R. Barzaghi (Italy) areevaluating the quality of potential values obtained with the existing resources (surface gravity data,
global gravity models, topography models, regional geoid models, etc.) at GGOS core sites and
ITRF reference stations in order to establish if additional gravity surveys around these stations areneeded. A further goal of this working group is to identify the elements required to install ascientific operational infrastructure for the IHRS/IHRF, considering the existing gravity fieldrelated IAG services and highlighting missing elements and interfaces to be established within the
IGFS as natural home of the IHRS/IHRF.
Based on the advances and challenges described by Sánchez et al., (2021), the BN&O will workwith the GGOS Focus Area Unified Height System, the IGFS, the IAG Commission 2, and the
Bureau of Products and Standards to support the implementation of the IHRF. Immediate steps are
to include the IHRF station requirements in the description of the GGOS core sites (Appleby et al.,2015) and to support the design of the new IGFS element to maintain and provide the IHRS/IHRF.

1.4 Tide Gauge Network (PSMSL)
Tide gauge data are being used to develop ocean circulation, tidal and storm surge
models; monitor tsunamis, storm surges, and long-term sea-level changes; and help
validate satellite ocean surface altimeters. The two main issues with tide gauge
networks are the large number of gauges that do not have local GNSS (or DORIS) receivers
for accurate and continuous geo-location in the geodetic reference frame and the gaps
over large coastal and oceanic expanses due to either inoperative units or lackof instrumentation entirely.
The IGS is working with PSMSL to improve the co-location of the GNSS with the tidegauges. They are encouraging the geodetic community to properly deploy GNSS
receivers in close proximity to existing tide gauges, to make the resulting tide gauge
and GNSS data publicly available with in international data archives sanctioned by GLOSS,
IGS, GGOS, etc., to encourage the establishment of geodetic ties between the GNSS
receivers and tide gauges, to advocate for more absolute gravity sites at tide gauges, andto advocate for placement of tide gauges in regions void of such systems but of greatscientific and societal interest. In accomplishing these tasks, we recognize that
oceanographic, as well as geodetic, entities are involved (i.e., IOC/GLOSS, GCOS, or
GOOS).
A similar effort has long been made by IDS taking all opportunity to co-locate new DORIS
stations with tide-gauges. Half of the DORIS network is already co-located with tide-gauge.

. The Bureau will address this need at different institutional and political levels andprovide support to initiatives to improve the network situation.

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Bureau of Networks and Observations Implementation Plan
The Service is also planning to address three additional goals:• 1 year - We will update the PSMSL website to link to co-located GGOS services attide gauges• 1 year - PSMSL will update the ellipsoidal links available on our website(https://www.psmsl.org/data/obtaining/ellipsoidal_links.php) to a show rangeof GNSS solutions• 3 year - We will investigate using Interferometric Synthetic Aperture Radar(InSAR) to establish wide areas of land movement, for the development oflocalized flood risk products

Table 2.1-1: GGOS BN&O Specifications and Requirements Allocation
REQUIREMENTREFERENCEREQUIREMENT AND
INTERPRETATIONGGOS-Ops-1

Operate global networks ofgeodetic reference stations,gravimeters; support the longterm operation of tide gauges
relevant for GGOS.

BN&O

IAG services

GGOS-Ops-2

Operate a global sub-networkof core reference stations at
which the techniques are colocated.
Determine the survey ties
between the co-locatedtechniques.

BN&O

IAG services

BN&O/IERSWG ON ST&C

IAG services andspace geodesy
sites; individual
institutions
operating GGOS
sites; IERS

Process all geometric andgravimetric observations withan accuracy and consistencyof at least 1 ppb.

BN&O

IAG services

GGOS-Ops-3

GGOS-Ops-4

2.2

GGOS
ALLOCATION

IAG SERVICE (OROTHER ENTITY)
ALLOCATION

Schedule Baseline

The scheduled activities for each of the entities within the BNO are described in thesections below. The activity areas are summarized in Table 2.2-1 because they are too

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Bureau of Networks and Observations Implementation Plan
extensive for the table. The activity areas are divided into four sections: Communications
and Coordination Activities; Tasks on network planning and evaluation, Task areas of the
Networks/Services, and Tasks areas of the Standing Committees/Working Groups.

Fig. 2.2.1: Overview and schedule of BNO activities

2.2.1 Bureau of Networks and Observations
Overview and Schedule of BNO activities
All of the contributing IAG services will focus on their respective network coordination,
data acquisition, and data analysis to generate products for science and societal needs
articulated by GGOS. The services will constantly strive to improve the robustness andquality of their data and the results through improved procedures, technologies, andmodeling. The services and Committees give brief summary reports as a part of the
Bureau meeting; these are summarized in the Bureau reports.
1. Complete the ITRF2020 and characterize its performance in terms of accuracy
and spatial and temporal coverage; (IERS/Altamimi);

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Bureau of Networks and Observations Implementation Plan
2. Identify and describe the measurement objectives and station requirements for
the IHRF and the IGRF; as well as, mission requirements (gravity field, altimetry,
GNSS, SAR, etc.);
3. Characterize the current stations (VLBI, SLR, GNSS, DORIS, IHRF, IGRF) in terms of
performance for the ITRF and other applications; What are they contributing?
4. Using the performance of the current stations, stations with planned upgrades,and new stations in process, project the network status 5, 10 and 15 years in the
future;5. Using this information and the results from the newest releases of the ITRF, theIHRF and IGRF, project the quality of the ITRF and other data products 5, 10 and
15 years ahead; What do we think we can achieve?
6. Examine augmentation options of co-locations in space to these projected
networks; to achieve the ITRF, IHRF and IGRF requirements; Simulations andengineering studies; what benefit could we get; some talks already given by the
PLATO SC members; revisit studies already presented to ESA and NASA;
7. Can we get full Co-location value from SLR and VLBI sites located 100 – 200 kmapart, but connected with redundant GNSS measurements from a continuously
operating regional network;
8. What software and modeling needs require updates in order to improve theresults; Survey of Analysis groups;
9. Explore options for sites in Latin America, Africa, and Oceania; the UN GGIM
should be a useful to help attract new partners and partnerships
10. Help sell this program to interested parties in critical regions; nurturepartnerships.

2.2.2 BN&O Standing Committees and Working GroupThe main activities for the Bureau of Networks and Observations are shown in Fig. 2.2.1.
The activities are divided into the categories of coordination, level of effort for theServices, level of effort for the Committees/Working Group, most of the activities overthe next two years are level of effort. The deployment and upgrading of field stations has
been seriously delayed due to administrative issues and the Panvirus-19 epidemic.

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Bureau of Networks and Observations Implementation Plan
2.2.2.1 Standing Committee on Performance Simulations & Architectural Trade-Offs(PLATO)
Objectives
The PLATO Committee / Working Group has currently 12-member groups working on
simulations and data analysis covering the full range of existing ground and space assets,
including VLBI, SLR, GNSS, and DORIS. The main focus is on how do we use existingobservation capabilities (stations, observation concepts, tracking performance, etc.)
including co-location in space with existing and new dedicated satellites to best support
GGOS planning and implementation.
Project future network capability and examine trade-off options for station deployment
and closure, technology upgrades, the impact of site ties, additional space missions, etc.
to maximize the utility of the GGOS assets:•••

Use simulation techniques to assess the impact on reference frame productsof network configuration, system performance, technique and technology
mix, colocation conditions, site ties, space ties (added spacecraft, etc.),
analysis and modeling techniques, etc.;
Use and developing improved analysis methods for reference frame products
by including all existing data and available co-locations (i.e., include allsatellites and use all data types on all satellites);
Make recommendations on network configuration and strategies based on thesimulation and trade-off studies.

Investigations that are being included in the PLATO activity include studying the impact
of:
•
•
•

The full range of existing ground and space assets:
GNSS assets (ground and space)
SLR (beyond Lageos-1 and -2) including ranging to GNSS satellites;
LLR assets
VLBI assets including tracking of GNSS satellites;
Co-located assets in space (e.g. GRACE, OSTM/Jason-2)
Mixture of existing legacy stations and simulated next generation stations
Improved GNSS antenna calibrations and clock estimation strategies (GNSS
alone or when in combination with SLR, VLBI, and DORIS)
Anticipated improved performance of current systems:
Simulate the impact of upgrading existing stations and their procedures
Simulate the impact of additional ground surveys at colocation sites (site ties)
Potential future space assets: - Co-locate all four techniques in space on a
dedicated satellite

Tasks
•

20

Examining trade-off options for station deployment and closure, technology
upgrades, the impact of site ties, etc. and project future network capability

GGOS Bureau of Networks and Observations Implementation Plan for 2020 -2

Bureau of Networks and Observations Implementation Plan
based on network configuration projected by the BNO or relevant IAG services(IGS, ILRS, IVS, IDS);•

Investigating the impact of improved SLR tracking scenarios including sphericalsatellites, LEOs, and GNSS satellites and VLBI satellite tracking on reference
frame products;•

Identifying technique systematics by analyzing short baselines, data from newobservation concepts, and available co-locations (e.g., consistent processingof LEO and ground-based observations);
Investigating the best-practice methods for co-location in space and assessing
the impact of co-location in space on reference frame products based on
existing satellites and by simulation studies for proposed missions.

•2.2.2.2 Standing Committees on Data and Information
Objectives
Near term Metadata activity (NASA CDDIS)
CDDIS continues to add new data and derived product collections and further populate
collection-level metadata stored in the Earth Observation System Data and Information
System (EOSDIS) Common Metadata Repository (CMR). CDDIS is an EOSDIS Distributed
Active Archive Centers (DAACs) and thus utilizes the EOSDIS infrastructure to manage
collection and granule level metadata describing CDDIS archive holdings; these
metadata include 120 published DOIs representing DORIS, GNSS, and SLR data andderived product collections archived at the CDDIS archive. Since the AGU Fall Meeting2019 the CDDIS actively participates in the GGOS DOI Working Group, sharing NASA
Earth Science Data and Information System (ESDIS) DOI methods and best practices withthe greater Geodesy community.
Activities underway at CDDIS:
1. Complete collection level metadata related to CDDIS data and derived productholdings in the EOSDIS Common Metadata Repository (CMR)
2. Continue to re-ingest CDDIS data and derived product holdings in order toextract granule level metadata linked to these new collection level records
Longer-Term Metadata activity /Geoscience Australia)
Geoscience Australia is working on the Development of a Geodesy Markup Language(GeodesyML), for the GNSS community; potential for expansion to the other space
geodesy techniques and GGOS. The current study is identifying metadata standards andrequirements, assessing critical gaps and the how these might be filled, what changes areneeded in the current standards, and who are the key people who should work on it (morecomprehensive scheme). The schema that would be used by its elements for standardized
metadata communication, archiving, and retrieval. First applications would be theautomated distribution of up-to-date station configuration and operational information,

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Bureau of Networks and Observations Implementation Plan
data archives and catalogues, and procedures and central bureau communication. One
particular plan of great interest is a site metadata schema underway within the IGS Data
Center Working Group. This work is being done in collaboration with the IGS, UNAVCO,
SIO, CDDIS, and other GNSS data centers. The current activity is toward a means of
exchange of IGS site log metadata utilizing machine-to-machine methods, such as XML
and web services, but it is expected that this will be expanded to the other Services tohelp manage site related metadata and to other data related products and information.
Schema for the metadata should follow international standards, like ISO 19xxx or DIF, butshould be extendable for technique-specific information, which would then be accessible
through the GGOS Portal.
Tasks:
Activities underway at CDDIS:
1. Complete collection level metadata related to CDDIS data and product holdingsin the EOSDIS Common Metadata Repository (CMR)
2. Re-ingest CDDIS data holdings in order to extract granule level metadata linked
to these new collection level records
Activities underway in Geodesy Markup Language (GeodesyML) System
1. Review and document the metadata and standards requirements of precise
positioning users in expected high use sectors (e.g. precision agriculture,
intelligent transport, marine, location-based services etc.).
2. Assess and document the critical gaps in standards which restrict how Findable
Accessible Interoperable and Reusable (FAIR) precise positioning data is for the
expected high use sectors.
3. Record use cases of standards being applied well and the benefits it provides tousers.
4. Review the “use cases” of geodetic data developed by Geoscience Australia andthe IGS Data Center Working Group.
(https://drive.google.com/drive/folders/1L792ImLktAiAbmhX9WZhvHrXB3BMD0
0G?usp=sharing) and document what work and time would be required toensure these use cases can be met in international standards. This could be:• Identify which gaps can be filled by GeodesyML• Identify which components of GeodesyML would be better, handled by /integrated with, existing standards (such as TimeSeriesML, SensorML,
Observations and Measurements) where possible.
• Identify which components of already existing international geospatial
infrastructure can be approached (such as the European Inspire initiative)• Advise on who we should engage with from the OGC/ISO community tofacilitate a change to a standard to meet our requirements.
5. Work with Project Partners to develop and test other use cases (e.g. integrationof geodetic data with geophysics data (e.g. tilt meters), Intelligent Transport

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Bureau of Networks and Observations Implementation Plan
Sector data, mobile applications). Then, document what work and time would be
required to ensure these use cases can be met in international standards.
6. Provide advice on how to best engage with the right communities to learn fromtheir experiences, test their tools and influence the development of required
standards.
Table 1: Research Projects
Research ProjectRP 1 – Improving the value of
Positioning Australia Products

Project
Component
RP 1.1: Develop and confirm GNSS value chains
RP 1.2: Identification of gaps in current standards

RP 2 – Extension of GeodesyML

PR 1.3: Developing and distributing customized GNSS
metadata profiles for industry
PR 4.1: OGC Innovation ProgramPR 4.2: GeodesyML adopted as a community standard

Table 2: Tasks
Project
Task Details
Component
RP 1.1

RP 1.2
RP 1.3RP 4.123• Engage with representatives from all industry sectors to develop
GNSS value chain diagrams (how users get and use precise positioningdata).
• To identify and address any remaining critical gaps in ISO and OGC
standards which will inhibit uptake of precise positioning data.
• Establish detailed, community-specific requirements for FAIR
geodetic and positioning metadata and setup a FAIRness compliancetest.
• Develop a GNSS metadata profile(s) for specific user sectors.
• Develop education material to explain how user groups can use
GNSS metadata profiles.
• Engage with industry to test the GNSS metadata profile(s) for user
acceptance.
• Revise GNSS metadata profile(s) based on user feedback.
• Distribute via GA website.
• Expand the information model of GeodesyML with required
metadata for end-users (as identified in RP 1).
• Revise and expand the information model of GeodesyML toensure the provided precise positioning data is FAIR.
• Investigate applicability of OGC API for provision of precise
positioning data to the end-users.

GGOS Bureau of Networks and Observations Implementation Plan for 2020 -2

Bureau of Networks and Observations Implementation Plan
• Supervise improvement of GeodesyML and coordinate these
efforts within OGC Innovation Program.
• Development, implementation and testing of GeodesyML
against current standard practice• Engage with Standards Australia to develop an adoption path forGeodesyML in ISO and OGC.
• Engage with ISO and OGC to propose GeodesyML as a community
standard.
• Work through ISO and OGC process to respond to changes andsuggestions made by ISO and OGC

RP 4.2

Table 3: Deliverables
Project
Deliverable Details
ComponentDue

RP 1.131 Dec 2020

GNSS value chain diagrams for 17 different user applications;
2 for each of the high value sectors and 1 for each of theother identified sectors.
A strategy to address each of the gaps in the standards
identified in RP 1.1 and PA1003.
GNSS metadata profile(s) addressing specific Positioning
Australia user sectors.
Acceptance of GeodesyML in the OGC Innovation Programand adherence to terms of the Program.
Incorporate improvements to GeodesyML as identified in RP
1 and RP2.

RP 1.2
RP 1.3RP 4.1
RP 4.230 Jun 2021
31 Dec 2021
30 Jun 2021
31 Dec 2022

2.2.2.3 Standing Committee on Satellite Missions
Objectives
Improve coordination and information exchange with the missions for better groundbased network response to mission requirements and space-segment adequacy for therealization of GGOS goals
•

•
•
•

Advocate, coordinate, and exchange information with satellite missions as partof the GGOS space infrastructure, for a better ground-based network responseto mission requirements and space-segment adequacy for the realization of the
GGOS goals.
Assess current and near-future satellite infrastructure and their compliance withGGOS 2020 goals;
Support proposals for new mission concepts and advocate for needed missions;Interfacing and outreach with other components of the Bureau; especially theground networks component, the simulation activity (PLATO), as well as the
Bureau of Standards and Products.

Tasks

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Bureau of Networks and Observations Implementation Plan
•
•
•
•
•
•
•
•

•

Set-up of a new concept of the Standing Committee to increase participation bypotential members;
Continue the regular activities, i.e. updating the two central lists, supporting
future satellite missions, etc.
Work with the Coordinating Office to set up and maintain a Satellite Missions
Committee section on the GGOS website;
Evaluate the contribution of current and near-term satellite missions to the
GGOS 2020 goals;
Work with GGOS Executive Committee, Focus Areas, and data productdevelopment activities (e.g., ITRF) to advocate for new missions to support GGOS
goals;
Support the Executive Committee and the Science Committee in the GGOSInterface with space agencies;
Advocate and support national and international space agencies in theirprocesses towards future gravity field missions, by providing material and taking
part in studies that support the realization of such concepts;
Increase the exchange and collaboration with PLATO; set up a more formal
procedure of collaboration; discuss needs and run simulations to study the
impact of future satellite missions, identify gaps for fulfilling the GGOS goals, etc.
Evaluation of cubesats and cubesat formations as complementaryelement of the GGOS (satellite) infrastructure

2.2.2.4 IAG Joint Working Group on Site Survey and Co-location (w/ IERS) 1.2.1:
The Working Group has a new set of terms and has received confirmation of newparticipants in the group. We would continue to encourage participation from any
agency or community that is conducting research, improving protocols, or completing
field surveys of local ties as sites with various space geodesy techniques present. Ourgroup has representation from all of the techniques and has continued to shareimproved protocols, technologies, and instrumentation to provide the most accurate tie
measurements possible for all sites around the world. We reminded participants toshare their contributions of local tie data for inclusion into ITRF2020.
•

Roles/Objectiveso Enhance and improve knowledge of local tie surveys through applied fieldpractice, research, and dissemination of materials developed.
o Share methodology of existing surveys to maintain consistency andimprove future results by isolating systematic errors.
o Share results and research internationally to improve protocols andcoordinate work.
o Coordinate the collection of local tie survey data results and associatedmetadata in a consistent fashion.

•

25

Committee leads and Membership (could be a link)o R. Hippenstiel, S. Bergstrand
GGOS Bureau of Networks and Observations Implementation Plan for 2020 -2

Bureau of Networks and Observations Implementation Plan
https://www.iers.org/IERS/EN/Organization/WorkingGroups/SiteSurvey/
sitesurvey.html (To be updated.)
Recent progress/Plans
o Improvements made to standardizing report and data submissions oflocal tie surveys to provide consistency across all agencies. Survey data
has recently been reported with new standards in place.
o Additional standard operating procedures are being written (NGS/USA) toaccount for new routines and laser tracking instrumentation being usedin recent local tie surveys.
o Local tie surveys were largely put on hold due to COVID-19 pandemic.
o Upcoming surveys planned at National Radio Astronomy Observatory(New Mexico, USA) and Goddard Geophysical and Astronomical
Observatory (Maryland, USA).
o Group is continuing to explore methodologies to measure and quantify
antenna deformation. Research and continued field tests using laser
scanning and terrestrial inSAR have been discussed.
o US (NGS) team has developed deflection of vertical (DoV) measurement
capabilities utilizing a robotic total station and camera.
o Submission of local tie metadata for the inclusion of the ITRF2020
development.
o NGS and NGA will complete side-by-side local tie survey observations andtraining in May.
Key issueso Investigate thermal and gravitational deformationo Consider importance and inclusion of DoV observationso Consistent formatting and reporting of survey results
Key Publications and Meetingso Most conferences were cancelled though we’ve maintained
communications about chairing sessions at upcoming events.
Longer-term Goals
o Implement newly developed DoV collection procedures after testing anddocumentation is complete.
o Further the discussions and potential field protocols for deformation.
o Discuss and study creating ties between sites of further distances by
incorporating continuous GNSS at more facilities.
o

•

•

•

•

2.3

Resources

The resources that make the Bureau possible are tabulated in Table 1.3-1. The
participating institutions cover material resources, travel, and other costs such as meetingrooms and teleconferences. The Bureau plan recognizes that we can declare the ideal, we
can issue guidelines and standards, and we can advocate, but we have very limited control

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Bureau of Networks and Observations Implementation Planover the allocation of resources except through persuasion. The realization of theinfrastructure will depend upon the resources that our participants are willing tocontribute, the cooperation that participants are willing to undertake, geographic,
political and other practical realities, and the influence that we as GGOS can exert.

3.0 CHANGE LOG
Table 3-1: Bureau of Networks and Observations Implementation Plan Change Log
VERSION

RELEASE DATE

0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9

141207150326150531First draft for review
Draft submitted to CB for review
Second draft submitted to CB for review

160106170201

Plan 2017 -18; Draft 2
Plan 2017 – 18; Draft 3
Plan 2020 - 21; Draft
Plan 2020 – 22; Draft for review
Plan 2022 – 22; Final & approved version

210304210322SYNOPSIS OF RELEASE

4.0 Appendices
4.2

Abbreviations

AGU

American Geophysical Union

AOGS

Asia Oceania Geosciences Society

ASI

Agenzia Spaziale Italiano, Italy

BKG

Bundesamt für Kartographie und Geodäsie, Frankfurt/Main, Germany

BN&C

Bureau of Networks and Communication

BN&O

Bureau of Networks and Observations

BP&S

Bureau of Products and Standards

CB

Coordinating Board

CEOS

Committee on Earth Observation Systems

CfA

Center for Astrophysics, USA

CHAMP

Challenging Mini-Satellite Payload

27

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Bureau of Networks and Observations Implementation PlanCO

Coordinating Office

CSM

Committee on Satellite Missions

CRF

Celestial Reference Frame

DORIS

Doppler Orbitography by Radiopositioning Integrated on Satellite

EC

Executive Committee

EGU

European Geosciences Union

ESA

European Space Agency

FTE

Full-Time Equivalent

GEO

Group on Earth Observation

GEOSS

Global Earth Observation Systems of Systems

GFZ

GeoForschungsZentrum, Germany

GGIM

Global Geospatial Information Management

GGOS

Global Geodetic Observing System

GIMS

GGOS Integrated Master Schedule

GGOS

Global Geodetic Observing System

GLOSS

Global Sea Level Observing System

GML

Geography Markup Language

GNSS

Global Navigation Satellite System

GOCE

Gravity field and steady-state Ocean Circulation Explorer

GOOS

Global Ocean Observing System

GPS

Global Positioning System

GRACE

Gravity Recovery And Climate Experiment

GRACE-FO

Gravity Recovery And Climate Experiment Follow-On

GRASP

Geodetic Reference Antenna in Space

GSFC

Goddard Space Flight Center, USA

GTRF

Global Terrestrial Reference Frame

IAG

International Association of Geodesy

IAU

International Astronomical Union

ICSU

International Council for Science

IDS

International DORIS Service

IERS

International Earth Rotation and Reference Frame Service

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Bureau of Networks and Observations Implementation Plan
IfE

Institut fuer Erdmessung, University of Hannover, Germany

IGFS

International Gravity Field Service

IGN

Institut National de l’Information Géographique et Forestière, France

IGS

International GNSS Service

IGRF

International Gravity Reference Frame

IHRFInternational Height Reference FrameILRSInternational Laser Ranging Service

IOCIntergovernmental Oceanographic Commission

ITRF

International Terrestrial Reference FrameIUGGInternational Union of Geodesy and Geophysics

IVS

International VLBI Service

JPL

Jet Propulsion Laboratory, USA

LAGEOS

LASer GEOdynamics Satellite

LARES

LAser RElativity Satellite

LARGE

LAser Ranging to GNSS s/c Experiment

LEO

Low Earth Orbiter

NASA

National Aeronautics and Space Administration, USA

NOC

National Oceanography Centre, UK

PLATO

Performance Simulations & Architectural Trade‐OffsPM

Polytechnic University of Milan, Italy

PPPowerPoint

PSMSL

Permanent Service for Mean Sea Levels/cSpacecraft

SLR

Satellite Laser Ranging

SMWG

Satellite Missions Working Group

SOPAC

Scripps Orbit and Permanent Array Center, USASP

SP Technical Research Institute of Sweden

ST&C

Survey Ties and Co-location

TBD

To Be Determined

TIGA

IGS Tide Gauge Working Group

ToR

Terms of Reference

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Bureau of Networks and Observations Implementation Plan
TRF

Terrestrial Reference Frame

TUM

Technical University of Munich, Germany

UMBC

University of Maryland, Baltimore County, USA

UN

United Nations

VLBI

Very Long Baseline Interferometry

WG

Working Group

4.3 Glossary[LIST ANY DEFINITIONS RELEVANT TO THE PLAN USING TABLE 4.3-1][CONSIDER CREATING A GGOS-COMMON LIST OF DEFINITIONS ON-LINE AT THE GGOS PORTAL/WEBSITE]
Table 4.3-1: Terms and Definitions
TERM[Term goeshere]
[Term goeshere]

DEFINITION[Definition goes here][Definition goes here]

4.4 References[GGOS 2020]: Global Geodetic Observing System: Meeting the Requirements of a Global
Society on a Changing Planet in 2020", H. -P. Plag and M. Pearlman (editors),
Springer, 2009
[GGOS ToR] Terms of Reference of the Global Geodetic Observing System (GGOS), IAG
Executive Committee, IUGG XXV General Assembly, Melbourne, Australia, July
2011.
Appleby G, Behrend D, Bergstrand S, Donovan H, Emerson C, Esper J, Hase H, Long J, Ma
C, McCormick D, Noll C, Pavlis E, Ferrage P, Pearlman M, Saunier J, Stowers D, Wetzel S(2015) GGOS Requirements for Core Sites, Global Geodetic Observing System (GGOS),
Revision 2 - Draft 3.4, https://cddis.nasa.gov/docs/2015/SiteRecDoc_Rev2_D3.4.pdf.

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Behrend, D., "Data Handling within the International VLBI Service", Data Science Journal,
Vol. 12, pp. WDS81–WDS84, ISSN 1683-1470, 17 February 2013. DOI 10.2481/dsj.WDS011
Boy J, Barriot J, Förste C, Voigt C, Wziontek H (2020) Achievements of the first 4 years of
the International Geodynamics and Earth Tide Service (IGETS) 2015–2019. In:
International
Associationof
Geodesy
Symposia,
Springer,https://doi.org/10.1007/1345_2020_94
Dow, J.M., Neilan, R. E., and Rizos, C., The International GNSS Service in changing
landscape of Global Navigation Satellite Systems, Journal of Geodesy (2009) 83:191–
198, DOI: 10.1007/s00190-008-0300-3
Drewes H, Kuglitsch F, Ádám J, Rózsa S (2016) Geodesist’s Handbook 2016, J Geod 90,
907, https://doi.org/10.1007/s00190-016-0948-z.
Ihde J, Sánchez L, Barzaghi R, Drewes H, Foerste C, Gruber T, Liebsch G, Marti U, Pail R,
Sideris M (2017) Definition and proposed realization of the International Height
Reference
System(IHRS).
SurveysinGeophysics,
38(3),
549-570,
https://doi.org/10.1007/s10712-017-9409-3.
Morelli C, Gantar C, Honkasalo T, McConnell R, Tanner J, Szabo B, U U, Whalen C (1974)
The International Gravity Standardization Net 1971 (I.G.S.N.71). International Associationof Geodesy, Special Publication 4 https://apps.dtic.mil/dtic/tr/fulltext/u2/a006203.pdf.
Pavlis, E. C. (2008), SLR and Global Reference Frames over the Next Decade, NAS NRC
Panel on National Requirements for Precision Geodetic Infrastructure, June 11-13, 2008,
University of Colorado at Boulder, Boulder, Colorado.
Pearlman, M., Noll C., Pavlis E., Lemoine F., Combrink L., Degnan J., Kirchner G.,
Schreiber U., The ILRS: approaching twenty years and planning for the future, Journal of
Geodesy, 2019, DOI: https://doi.org/10.1007/s00190-019-01241-1
Sánchez L, Barzaghi R (2020) Activities and plans of the GGOS Focus Area Unified Height
System,EGU
GeneralAssembly
2020,
EGU2020-8625,
https://doi.org/10.5194/egusphere-egu2020-8625.
Sánchez L, Ågren J, Huang J, Wang YM, Mäkinen J, Pail R, Barzaghi R, Vergos GS, Ahlgren
K, Liu Q (2021). Strategy for the implementation of the International Height Reference
System (IHRS), J Geod, Special Issue on Reference Systems in Physical Geodesy, accepted
Service for Mean Sea Level. Journal of Coastal Research: Volume 29, Issue 3: pp. 493 –
504. doi:10.2112/JCOASTRES-D-12-00175.1
Willis, P.; Lemoine, F.G.; Moreaux, G.; Soudarin, L.; Ferrage, P.; Ries, J.; Otten, M.;
Saunier, J.; Noll, C.; Biancale, R.; Luzum, B., 2016. The International DORIS Service (IDS),

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recent developments in preparation for ITRF2013, IAG SYMPOSIA SERIES, 143, 631-639,
DOI: 10.1007/1345_2015_
Willis, P.; Lemoine, F.G.; Moreaux, G.; Soudarin, L.; Ferrage, P.; Ries, J.; Otten, M.;
Saunier, J.; Noll, C.; Biancale, R.; Luzum, B., 2016. The International DORIS Service (IDS),
recent developments in preparation for ITRF2013, IAG SYMPOSIA SERIES, 143, 631-639,
DOI: 10.1007/1345_2015_164
Wziontek, H., H. Wilmes, S. Bonvalot. AGrav: An international database for absolutegravity measurements. Geodesy for Planet Earth (S. Kenyon at al. eds), International
Association of Geodesy Symposia, 136, 1035-1040, Springer-Verlag, Berlin. 2011. DOI
10.1007/978-3-642-20338-1_130.
Wziontek H, Bonvalot S, Falk R et al. (2021) Status of the International Gravity Reference
System and Frame. J Geod 95, 7. https://doi.org/10.1007/s00190-020-01438-9

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