Vol. 94 - No. 11 - November 2020

Journal ofGeodesy
The
Geodesist’sHandbook
2020

A constituent Association of theInternational Union of Geodesy andGeophysics (IUGG)
Edited by:
IAG Office
Markku Poutanen
Finnish Geospatial Research Institute FGINational Land Survey of Finland
Geodeetinrinne 202430 Masala, Finlande-mail: IAG.office@nls.fi
IAG Communication and Outreach Branch (COB)
Szabolcs Rózsa
Department of Geodesy and Surveying
Budapest University of Technology and Economics
P.O.Box 91
H-1521 Budapest, Hungary
e-mail: szrozsa@iag-aig.org

Global Geodetic Observing System (GGOS)

203

GGOS Bureau of Networks and Observations
Director: Michael Pearlman (USA)The Bureau of Networks and Observations develops a strategy to design, integrate and maintain the fundamental infrastructure in a sustainable way to satisfy the long-term (1020 years) requirements identified by the GGOS Science
Panel. Primary emphasis must be on sustaining the infrastructure needed to maintain the evolving global reference
frames, while at the same time ensuring the broader supportof the scientific applications of the collected data. Coordinating and implementing the GGOS co-located station network is a key focus for the Bureau.

GGOS Bureau of Networks & Observations
 IAG Service Network Representatives
 Committee on Performance Simulations andArchitectural Trade-offs
 Committee on Data and Information
 Committee on Satellite Missions

IGFS:

Riccardo Barzaghi (Italy)
George Vergos (Greece)

IVS:

Hayo Hase (Germany)
Dirk Behrend (USA)ILRS:

Toshi Otsubo (Japan)
Jean-Marie Torre (France)

IGS:

Allison Craddock (USA)Gary Johnston (Australia)

IDS:

Jérôme Saunier (France)
Guilhem Moreaux (France)

Tide Gauges:

Elizabeth Bradshaw (UK)Lesley Rickards (UK)Richard Gross (USA)In addition, the IERS Working Group on Site Survey andCo-location also participates in the BN&O activities; thisWorking group is now in the process of reorganization with
Ryan Hippenstiel / NOAA as Chair.

StructureObjectives

Director: Michael Pearlman (USA);
Secretary: Carey Noll (USA)
Analysis Representative: Erricos Pavlis (USA)The Bureau of Networks and Observations (BNO) supports
the networks capability available to the IAG in its goal toprovide geodetic data products of sufficient quantity, qualityand temporal and spatial resolution to improve our understanding of the dynamic Earth for both scientific understanding and societal needs. Fundamental to achieving
reaching this goal is the maintenance and further development of the globally available terrestrial and celestial reference frames, which are the basis for our metric measurements over space, time, and evolving technology.
The BN&O advocates for implementation of the global
space geodesy network of sufficient capability and geographic coverage to achieve data products essential for

Members:
PLATO Committee:

Daniela Thaller (Germany)
Benjamin Männel (Germany)

Missions Committee: Roland Pail (Germany)
C.K. Shum (USA)
Data and Information: Nicholas Brown (Australia)
Carey Noll (USA)204

GGOS and serves as a coordinating point for the Services tomeet, discuss status and plans, and examine common paths
for meeting GGOS requirements. Committees and working
groups are included in the Bureau in recognition of theirsynergistic role with Bureau activities.
The role of the BNO is to: Advocate for the expansion and upgrade of the space
geodesy network for the maintenance and improvementof the reference frame and other GGOS priorities; Main
focus will be on the Reference Frame; but the otherapplications need to be accommodated; Encourage partnerships to build and upgrade network
infrastructure Organize and expand the GGOS affiliated network; Monitor network status; projected network evolution
based on input from current and expected future
participants, estimate performance capability 5 and 10years ahead; 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, andnetwork trade of options (PLATO);
 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 (NickBrown at GA) (Committee on Data and Information); Provide the opportunity for representatives from theServices and the Standing Committees to meet and share
progress and plans; discuss issues of common interest;
meetings at EGU, AGU, GGOS Days, etc.;
 Talks and posters on the Bureau at EGU, AGU, JPGUAGU, AOGS meetings, etc.;
 Letters/documentation to support stations, current/ new
missions, and analysis centers;

The Geodesist’s Handbook 2020Tasks
 Continue recruiting station membership in the GGOS
Network through the CfP; issue membership certificates(great response); Continue monitoring network status and plans; develop
next network projection status for 5 and 10 years ahead; Provide next update of the “Guideline for GGOS Core
Sites and Co-locations Sites” document; Work with the IGFS and IHRF, the PSMSL and theother services to integrate relevant parameters fromother ground networks (gravity field, tide gauges, etc.)
into the GGOS network to support GGOS requirements
including the reference frame, a unified height system,etc.; advocate for installation of GNSS receivers at
appropriate tide gauges; Global Geodetic Observing
System (GGOS) Support the technique Services on the promotion ofrecommended
technologies/configurations
andprocedures in the establishment of new sites and theupgrading of current sites, and in the evaluation ofperformance of new stations and new capabilities after
they become operational;
 Continue simulation and trade-off studies for network
options (PLATO Committee)
 Continue metadata systems development; target phase 1(data products) for 2020 (Committee on Data andInformation)
 Improve communication and information exchange andcoordination with the space missions; (Committee onSatellite Missions) Work with the IERS Working Group on Site Survey andCo-location to improve the quality of site ties andinstrument reference points:
 Continue BNO meetings to meet, discuss status andplans, and examine common interests and requirements;
 Continue presentation at international meetings in BNO
activities and plans; Continue providing letters and documentation support
 Update the Bureau web pages for public use (to becompatible with the new GGOS website in process;Global Geodetic Observing System (GGOS)

205

Committees of the Bureau of Networks and Observations

BNO C1: Committee on Performance Simulations and Architectural Trade-Offs(joint with IAG Sub-Commission 1.1)
Chair:
Daniela Thaller (Germany)
Vice-Chair: Benjamin Maennel (Germany)
Objective
The PLATO Committee / Working Group has currently 12member 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 existing observation 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 onreference frame products of network configuration,system performance, technique and technology mix,
colocation conditions, site ties, space ties (addedspacecraft, etc.), analysis and modeling techniques, etc.;
 Use and developing improved analysis methods forreference frame products by including all existing dataand available co-locations (i.e., include all satellites anduse all data types on all satellites);
 Make recommendations on network configuration andstrategies based on the simulation 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:o GNSS assets (ground and space)o SLR (beyond Lageos-1 and -2) including ranging to
GNSS satellites;o LLR assets
o VLBI assets including tracking of GNSS satellites;o Co-located assets in space (e.g. GRACE, OSTM/Jason-2)
o Mixture of existing legacy stations and simulated
next generation stations
o 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:
o Simulate the impact of upgrading existing stationsand their procedureso Simulate the impact of additional ground surveys atcolocation sites (site ties) Potential future space assets: - Co-locate all fourtechniques in space on a dedicated satellite
Tasks
 Examining trade-off options for station deployment andclosure, technology upgrades, the impact of site ties,etc. and project future network capability 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 spherical satellites, LEOs, andGNSS satellites and VLBI satellite tracking on reference
frame products;
 Identifying technique systematics by analyzing shortbaselines, data from new observation concepts, andavailable co-locations (e.g., consistent processing ofLEO and ground-based observations);
 Investigating the best-practice methods for co-locationin space and assessing the impact of co-location in spaceon reference frame products based on existing satellites
and by simulation studies for proposed missions.

206

BNO C2: Committee on Data and Information
Chair:
Nicholas Brown (Austria)
Vice-Chair: Carey Noll (USA)The Geodesist’s Handbook 2020

metadata should follow international standards, like ISO
19xxx or DIF, but should be extendable for technique-specific information, which would then be accessible throughthe GGOS Portal.
Tasks:

Objectives
The Committee on Data and Information had two GGOS
objective areas: Development and implementation of a portal; Development and implementation of a metadata scheme
Initial work on the portal was done by Bernd Richter. Whenhe retired, the task was transferred to the GGOS Coordinating Office.
Near term Metadata activity (Carey Noll/CDDIS)
CDDIS is implementing collection-level metadata throughthe 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 DOIs associatedwith the CDDIS archive contents. The CMR is accessible
through APIs and can be used in the future by GGOS to findgeodetic data and products available through the CDDIS.
Longer-Term Metadata activity (Nick Brown / Geoscience Australia)
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 and requirements, assessing critical gaps and the how these might befilled, what changes are needed in the current standards, and
who are the key people who should work on it (more comprehensive scheme). The schema that would be used by its
elements for standardized metadata communication, archiving, and retrieval. First applications would be the automateddistribution of up-to-date station configuration and operational information, data archives and catalogues, and procedures and central bureau communication. One particularplan 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 theother Services to help manage site related metadata and toother data related products and information. Schema for theActivities underway at CDDIS:
1. Complete collection level metadata related to CDDIS
data and product holdings in the EOSDIS Common
Metadata Repository (CMR)
2. Re-ingest CDDIS data holdings in order to extract
granule level metadata linked to 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 expectedhigh 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 theexpected high use sectors.
3. Record use cases of standards being applied well andthe benefits it provides to users.
4. Review the “use cases” of geodetic data developed by
Geoscience Australia and the IGS Data Center Working
Group and document what work and time would be
required to ensure these use cases can be met ininternational standards. This could be:o Identify which gaps can be filled by GeodesyMLo Identify which components of GeodesyML would bebetter, handled by / integrated with, existing standards(such as TimeSeriesML, SensorML, Observations andMeasurements) where possible.
o Identify which components of already existing
international geospatial infrastructure can beapproached (such as the European Inspire initiative)o Advise on who we should engage with from theOGC/ISO community to facilitate a change to a
standard to meet our requirements.
5. Work with Project Partners to develop and test otheruse cases (e.g. integration of geodetic data withgeophysics data (e.g. tilt meters), Intelligent Transport
Sector data, mobile applications). Then, document whatwork 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 rightcommunities to learn from their experiences, test theirtools and influence the development of requiredstandards.

Global Geodetic Observing System (GGOS)BNO C3: Committee on Satellite Missions
Chair:
Roland Pail (Germany)
Vice-Chair: C.K. Shum (USA)Objectives
Improve coordination and information exchange with themissions for better ground-based network response to mission requirements and space-segment adequacy for the realization of GGOS goals
 Advocate, coordinate, and exchange information withsatellite missions as part of the GGOS space
infrastructure, for a better ground-based network
response to mission requirements and space-segment
adequacy for the realization of the GGOS goals.
 Assess current and near-future satellite infrastructure
and their compliance with GGOS 2020 goals;
 Support proposals for new mission concepts andadvocate for needed missions; Interfacing and outreach with other components of theBureau; especially the ground networks component, thesimulation activity (PLATO), as well as the Bureau ofStandards and Products.

207Tasks
 Continue the regular activities, i.e. updating the twocentral lists, supporting future satellite missions, etc.
 Work with the Coordinating Office to set up andmaintain a Satellite Missions Committee section on theGGOS 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 product development activities (e.g., ITRF) toadvocate for new missions to support GGOS goals;
 Support the Executive Committee and the Science
Committee in the GGOS Interface with space agencies; Finalize and publish (outreach) of Science and User
Requirements Document for future gravity field
missions.
 Increase the exchange and collaboration with PLATO;
set up a more formal procedure of collaboration; discussneeds and run simulations to study the impact of futuresatellite missions, identify gaps for fulfilling the GGOS
goals, etc.