Global Geodetic Observing System
GGOS Days 2021
ReportOctober 11-13, 2021
Video Conferenceggos.orgGlobal Geodetic Observing System
GGOS Days 2021 - Report
Contents
1

Introduction........................................................................................................................................... 2

2

Logistics ................................................................................................................................................. 2

3

List of Participants ................................................................................................................................. 3

4Group Photo .......................................................................................................................................... 6

5

Schedule ................................................................................................................................................ 7
Day 1 - Monday, October 11, 2021 - General, Internal and External Activities ........................................ 7
Day 2 - Tuesday, October 12, 2021 - GGOS Bureaus ................................................................................. 8
Day 3 - Wednesday, October 13, 2021 - GGOS Focus Areas ..................................................................... 8

6

General Report ...................................................................................................................................... 9

7

Appendix – Status Reports of GGOS Components .............................................................................. 11
7.1 GGOS Bureau of Networks and Observations ................................................................................... 11
7.2 GGOS Bureau of Products and Standards ......................................................................................... 16
7.3 GGOS Focus Area Unified Height System (FA-UHS) .......................................................................... 22
7.4 GGOS Focus Area Geohazards ........................................................................................................... 24
7.5 Focus Area: Geodetic Space Weather Research ............................................................................... 25

ggos.org

October, 2021

1

Global Geodetic Observing System
GGOS Days 2021 - Report
1

Introduction

GGOS Days is the annual meeting of GGOS during which the different components of GGOS meet andreport on their activities during the past year and their plans for the coming year. The meetings is focusedon strategic discussions rather than on formal reporting. The different components of GGOS are: GGOS
Consortium (large steering committee of GGOS), GGOS Coordinating Board (decision making body of
GGOS), GGOS Bureau of Networks and Observations, GGOS Bureau of Products and Standards, all 3 GGOS
Focus Areas as well as the GGOS Science Panel.
This year the GGOS Days was held as a video conference again, instead of the common face-to-facemeeting due to travel restrictions by the COVID-19 crises and uncertain situation.

2

Logistics

Chair:
Organizer:

Basara Miyahara (President of GGOS)
Martin Sehnal (GGOS Coordinating Office)Dates:

Monday, October 11, 2021
Tuesday, October 12, 2021
Wednesday, October 13, 2021

Duration:

2 hours each day

Time:Every day it started at the same time
Time Zone

CountryUTCTime
13:00-15:00

PDT

USA West Coast

06:00-08:00

EDT

USA East Coast

09:00-11:00

GMT-3

Argentinia

10:00-12:00

CEST / SAST Europe / South Africa

15:00-17:00

JST

Japan

22:00-00:00

AEST

Australia East Coast

00:00-02:00 (next day!!)

Recording:

The entire virtual conference was recorded. Parts of the recording are available on the
GGOS YouTube Channel. All presenters and participants agreed to publish the recorded
videos on the GGOS YouTube Channel.

Documents:

Please find the current status reports of GGOS components and all presentation slides at
GGOS Cloud: https://cloud.ggos.org/index.php/s/wA76j5WorEj4eG8

ggos.org

October, 2021

2

Global Geodetic Observing System
GGOS Days 2021 - Report3

List of Participants

Members of the GGOS Consortium, GGOS Coordinating Board, GGOS Bureaus, GGOS Focus Areas, GGOS
Science Panel, invited guests and all interested persons were highly welcome to attend this meeting. Overall three days 83 people attended this meeting, with a maximum of 63 and a minimum of 56 each day.

ggos.org

Participant

Country

Day 1

Day 2

Day 3

Basara Miyahara

Japan

x

x

x

Allison Craddock

USA

x

x

x

Mike Pearlman

USA

x

x

x

Richard Gross

USA

x

x

x

Martin Sehnal

Austriaxxx

Detlef Angermann

Germanyxxx

Zuheir Altamimi

FrancexxxThomas Gruber

Germanyxxx

Rolf Dach

Switzerland

x

x

x

Susanne Glaser

Germanyxxx

Sônia Costa

Brazilxx

x

Kevin Kelly

USA

x

x

x

Toshimichi Otsubo

Japan

x

x

x

Claudia Tocho

Argentinaxx

x

Kosuke Heki

Japan

x

x

x

Soudarin Laurent

Francexxx

Jaakko Mäkinen

Finlandx

x

x

Markku Poutanen

Finlandxx

x

Daniela Thaller

GermanyxxxSergei Rudenko

GermanyxxxAbel Garcia-Castellano

Spain

x

x

x

Mariana MoreiraPortugalx

x

x

Manuela Vasconcelos

Portugalxx

x

Laura Isabel Fernández

Argentinaxx

x

Elizabeth Bradshaw

UK

x

x

x

Yusuke Yokota

Japan

x

x

x

Stanislava Valcheva

Bulgariaxxx

October, 2021

3

Global Geodetic Observing System
GGOS Days 2021 - Report
Participant

Country

Day 1

Day 2

Day 3

Hartmut Wziontek

GermanyxxxHarald Schuh

GermanyxxxAndrew Matthews

UK

x

x

x

Valente Cuambe

Portugalxx

x

Mattia Crespi

Italy

x

x

x

Michela Ravanelli

Italy

x

x

x

x

x

x

Diogo Avelar
Zinovy Malkin

Russiax

Elena Martinez Sanchez

Spain

x

Hansjörg Kutterer

GermanyxJohannes Böhm

Austriaxx

Christoph Förste

GermanyxxEzequiel D. Antokoletz

Argentinaxx

Ignacio Parada

Chile

x

x

Gabriel Guimarães

Brazilx

x

Robert Heinkelmann

Germanyxx

Arturo Villiger

Switzerlandxx

Esther Azcue

Spain

x

x

Mathis Bloßfeld

Germanyxx

Sean Bruinsma

Francexx

Maik Thomas

Germanyxx

Axel Rülke

GermanyxxMarkus Rothacher

SwitzerlandxxJoão Salmim FerreiraPortugalx

Sultan Alshahrani

Saudi ArabiaxxHelena Ribeiro

Portugalxx

Yoshiyuki Tanaka

Japan

x

x

Ben Phillips

USA

x

x

Christopher Kotsakis

Greecexx

Riccardo Barzaghi

Italy

x

x

Larry Hothem

USA

x

x

Elena Yebesggos.org

x
x
x

x

x

October, 2021

4

Global Geodetic Observing System
GGOS Days 2021 - Report
Participant

Country

Day 1

Jose Antonio Tarrío

Chile

x

Marie-Francoise Lalancette

Francex

Edilberto Suárez Torres

Colombiax

Fuensanta G. Montesinos

Spain

x

Toshiki Kumazawa

Day 2

Day 3

x

Mario Moreno

Germanyx

Patrick Schreiner

Germanyx

E. Sinem Ince

Germanyx

Benjamin Männel

Germanyx

Kirsten Elger

GermanyxAssumpció Termens

Spain

x

Ryan HippenstielUSAx

Sergio Rozas

Chile

x

Juan Quilaleo

Chile

x

Georgios S. Vergos

Greecex

Léo Martire

USA

x

David Grzan

USAx

Kangkang Chenx

Attila KomjathyUSAx

Jianliang Huang

Canadax

Tilo Schöne

GermanyxJose Manuel Ferrandiz

Spain

x

Valentino Constantinou

USAxJohn RundleUSAx

Statistics:
Participants in total
Participants of day 1
Participants of day 2
Participants of day 3
Participants participated on all 3 days

ggos.org

83
63
56
56
34

Participants from Europe
Participants from North America
Participants from South America
Participants from Asia

October, 2021

49
13
9
6

5

Global Geodetic Observing System
GGOS Days 2021 - Report
4Group Photoggos.org

October, 2021

6

Global Geodetic Observing System
GGOS Days 2021 - Report5

Schedule

Day 1 - Monday, October 11, 2021 - General, Internal and External Activities
General:
5 min

Welcome and Instruction (B. Miyahara)

10 minGGOS & IAG Report (B. Miyahara)

5 min

New GGOS Strategic Plan – Workshop 2022 (B. Miyahara)

5 min

Recently finished IGS Strategic Plan – invited presentation (A. Craddock)

5 min

GGOS Days 2022 (B. Miyahara, D. Angermann)Internal Activities:
10 minGGOS Science Panel (K. Heki)

15 minGGOS Affiliate – New GGOS D-A-CH (H.J. Kutterer)

10 minGGOS Affiliate – GGOS Japan Report (T. Otsubo)

20 minGGOS Coordinating Office – New GGOS Website (M. Sehnal)

20 minWorking Group on “DOIs for Geodetic Data Sets” (K. Elger)

External Activities:
20 minggos.org

GGOS External Relations (A. Craddock)

October, 2021

7

Global Geodetic Observing System
GGOS Days 2021 - ReportDay 2 - Tuesday, October 12, 2021 - GGOS Bureaus
15 minITRF2020 report – invited presentation (Z. Altamimi)

45 min

BNO - Bureau of Networks and Observations
Report about GGOS BNO – Part 1 (M. Pearlman)
Working Group on Site Survey and Co-location (R. Hippenstiel)Standing Committee on PLATO (D. Thaller)

45 min

BPS - Bureau of Products and Standards
Report about GGOS BPS (D. Angermann)
Definition of Essential Geodetic Variables – EGVs (R. Gross)
Committee on Contributions to Earth System Modeling (M. Thomas)

Day 3 - Wednesday, October 13, 2021 - GGOS Focus Areas
30 minGGOS Focus Area: Unified Height System (L. Sánchez, R. Barzaghi)

20 minReport about GGOS BNO – Part 2 (M. Pearlman)

10 minShort Break

10 minUN-GGIM Subcommittee on Geodesy update (J. Bouman, B. Miyahara)

30 minGGOS Focus Area: Geodetic Space Weather Research (M. Schmidt, E. Forootan)

15 minGGOS Focus Area: Geohazards
Recent Activities of GGOS Geohazards Focus Area (J. LaBrecque, A. Craddock)
ITU Focus Group on AI for Natural Disaster Management - invited presentation(A. Craddock, J. Rudle, D. Grzan, A. Komjathy)

10 minggos.org

General discussion / Any other Business (All)

October, 2021

8

Global Geodetic Observing System
GGOS Days 2021 - Report
6

General Report

This year, due to the Corona pandemic, the GGOS Days 2021 were held as a completely virtual conference
like last year. We tried to attract more participants through social media (Twitter and LinkedIn) and with
the new GGOS website (blog and newsletter). We were very successful with this and a total of 83 people
attended this conference, which is a new record. In 2020 we had 49 attendees (virtual conference) andthe year before 21 attendees (hybrid conference) in total. We are very happy that so many people areinterested in GGOS. With this short general report, we would highlight the main points from this meeting.
At the GGOS Days 2021 it was stated that the GGOS Strategic Plan should be renewed. Therefore, astrategic plan workshop will be held in Munich next year directly after the GGOS days. The IAG Service IGS
had just completed the creation of the new IGS Strategic Plan, which was presented by Allison Craddock
in an invited presentation.
The Panel supported Hansjörg Kutterer presented the GGOS Affiliate organization GGOS D-A-CH, newly
founded in May 2021, and its future plans to strengthen activities in the German-speaking region(Germany, Austria and Switzerland). Toshimihchi Otsubo also presented update of GGOS Japan. GGOS DA-CH and GGOS Japan had first bilateral meeting to start discussion on possibility of future collaboration
among GGOS Affiliates. The newly developed GGOS website and the planned further developments were
presented by Martin Sehnal. As outreach of importance and role of geodesy to non-geodesists, new pages
on geodetic products were developed by the GGOS Bureau of Products and Standards (BPS) with support
by GGOS Science Panel, GGOS Coordinating Office, the GGOS Bureau of Networks and Observations (BNO)
and other colleagues. The pages were published in 2021 and are now available at new GGOS website. New
pages on geodetic observation are also developed by Laura Sánchez with support by Martin Sehnal andwill be published soon.
Kirsten Elger presented progress of the GGOS Working Group on “DOIs for Geodetic Data Sets” andreported current situation, issues and possible ways to appropriately mint DOIs to geodetic data sets.
At the end of the first day, Allison Craddock presented the activities of GGOS in the field of external
relations. In addition to existing collaborations, the new engagement in the ITU Focus Group "AI for
Natural Disaster Management" was highlighted. Another invited talk on the geodetic contribution to thisITU Focus Group, as part of the GGOS Focus Area Geohazards, was given on the third day of the GGOS
Days conference.
Two additional speakers were invited. Zuheir Altamimi presented the current status of ITRF2020 and
Johannes Bouman wanted to give a status report on the UN-GGIM Subcommittee on Geodesy and its
Global Geodetic Center of Excellence (GGCE). Unfortunately, Johannes was unable to give his
presentation, but Basara Miyahara attempted to give a status update.

ggos.org

October, 2021

9

Global Geodetic Observing System
GGOS Days 2021 - Report
On the second and third day of this conference, the GGOS Bureaus and GGOS Focus Areas presented theirstatus reports with invited speakers from the committees and working groups. Full details are in the status
reports from the GGOS components, which can be found in the appendix.

In the GGOS Bureau of Product and Standards (BPS) Detlef Angermann presented the intensive
involvement in the development of the geodetic product pages of the GGOS website and theparticipation in the rewrite of the IERS Conventions in the function as Chapter Expert for the"General Definitions and Numerical Standards". Invited presentations by Richard Gross on the"Definition of Essential Geodetic Variables (EGVs)" committee and by Maik Thomas on the"Contributions to Earth System Modeling" committee rounded out the BPS report.
Mike Pearlman reported on progress within the GGOS Bureau of Networks and Observations (BNO), in
particular the contribution to the development of the GGOS website, the closer collaboration between
ROSCOSMOS and ILRS and GGOS, and the response to the IAG questionnaire. Presentations by Daniela
Thaller on the PLATO Committee and by Ryan Hippenstiel on the “Site Ties and Co-location” Working
Group rounded out the BNO report.
Riccardo Barzaghi highlighted ongoing activities in the GGOS Focus Area "Unified Height System"
presentation and showed the status of the first static solution for the IHRF.
Allison Craddock explained the plans and collaboration under the "GNSS enhancement to Tsunami Early
warning Systems" (GTEWS) in the GGOS Focus Area Geohazards.
This conference concluded with a lively discussion on the creation of new IAG services for existinggeodetic products such as "Altimetry Service", "Sea Level Service" or "Ice Mass Variation Service".
More information and details are in the Status Reports of the GGOS components and the presentation
slides of the talks which are available at GGOS Cloud. If you want to re-watch the recorded
presentations, please visit the GGOS You Tube Channel.

ggos.org

October, 2021

10

Global Geodetic Observing System
GGOS Days 2021 - Report
7

Appendix – Status Reports of GGOS Components

7.1 GGOS Bureau of Networks and Observations
STATUS REPORT

11/08/2021

GGOS Bureau of Networks and Observations
Mike Pearlman and many others
Center for Astrophysics
BureauCurrent Status and Progress:•

Bureau posters at AGU and IAG Symposium;•

Continued recruiting for the GGOS Affiliated Network;•

MOU completed with ROSCOSMOS for closer cooperation with ILRS and GGOS•

Monitored network status; projected network evolution for the reference frame based on input
from current and expected future participants, estimate performance capability 5 and 10 years
ahead;•

Letters/documentation to support stations, current/ new missions, and analysis centers;•

Reviewing IAG Questionnaire material for posting in the IAG website;•

Supported activities by the Standing Committees;

Plans:•

Continue advocating for the expansion and upgrade of the space geodesy network for the
maintenance and improvement of the reference frame and other GGOS priorities; encourage
partnerships to build and upgrade ground stations;•Continue recruiting stations for the GGOS Affiliated Network;•

Continue monitored network status; project network evolution for the reference frame based on
input from current and expected future participants,•

Continue the work of the Standing Committees;•

Letters/documentation to support stations, current/ new missions, and analysis centers, etc.

ggos.org

October, 2021

11

Global Geodetic Observing System
GGOS Days 2021 - Report•

Provide the opportunity for representatives from the Services and the Standing Committees tomeet and share progress and plans; discuss issues of common interest; meetings at EGU, AGU,
GGOS Days, etc.;

Services•

The Services continue the expand their networks as funding and conditions allow. Significant
geographic gaps still exist. Technology updates continue as funding permits. Progress has slowed
due to the pandemic.

Standing Committees•

Standing Committee on Performance Simulations & Architectural Trade-Offs (PLATO)(Daniela Thaller/BKG and Benjamin Maennel/GFZ)
Current Status and Progress:•

PLATO-linked session at EGU 2021 with 16 contributions (G2.3 „New strategies forconsistent geodetic products and improved Earth system parameters”)•

Annual meeting held May 18, online•

Examples of recently finished and ongoing studies•

Simulation studies on possible extension of Australian SLR network (DGFI/TUM)•

Simulation studies on differential LLR (IfE, Hannover)•

Simulation studies on VLBI observation to Galileo satellites (TU Vienna)•

Simulation studies on future GNSS constellation (GFZ, TU Berlin)

Plans:

ggos.org•

Re-activate pilot project on exchanging simulation data; SLR and VLBI simulations andsubsequent processing results to be compared between software packages; period of
CONT17 selected;•

Simulations to project the improvements in the ITRF related to network and station
updates (depending on BNO and Services)•

Encourage additional groups to contribute to PLATO

October, 2021

12

Global Geodetic Observing System
GGOS Days 2021 - Report•

Standing Committee on Data and Information (Nicholas Brown/GA, Sandra Blevins/NASA)
Geoscience Australia (GA)
Current Status and Progress:•

Geoscience Australia is leading a global initiative to identify and meet user requirements
for Findable, Accessible, Interoperable and Reusable (FAIR) geodetic data. This initiative
is paying particular attention to ensuring the new and emerging user base of positioning
information (e.g. location based services and intelligent transport services) have FAIR
geodetic data;•

In recent months, GA and its collaborators have conducted a user requirements survey
across a range of industrial and societal user sectors of geodetic data to identify criticalgaps in standards identified in which could inhibit the uptake of precise positioning
products. There were over 100 responses covering data standards scalability issues, lackof encoded metadata; technology, security and block chain technology, performance fordemanding positioning applications, understanding the meaning of FAIR – Findable,
Accessible, Interoperable, and Reusable Data /Metadata;

Plans:•

Through a process of user consultation and engagement, provide user sectors (e.g.
agriculture) with fit-for-purpose metadata profiles which meet their current and future
requirements.

•

Revise and expand the information model of GeodesyML to ensure the provided precise
positioning data is FAIR.

•

Progress GeodesyML development with assistance from the OGC Innovation Program.

•

Develop, implement and test GeodesyML against current standard practice•

Welcome anyone who would like to assist in the development and refinement of
GeodesyML to please contact us and get involved.

CDDIS
Current Status and Proress:•

ggos.org

CDDIS is actively progressing in the implementation of ongoing tasks, including thefollowing:• Reprocessing and re-ingest of data and derived products for all CDDIS geodetic
techniques (DORIS, GNSS, SLR, VLBI). Re-ingest of most data sets covering all
geodetic techniques are complete, and data product set re-ingest is underway. These
granule-level metadata will be updated in the EOSDIS Common Metadata Repository(CMR);

October, 2021

13

Global Geodetic Observing System
GGOS Days 2021 - Report•

Collaborating with the NASA ESESES MEaSUREs team to receive, ingest, and archive
new data product sets including GNSS geodetic displacement time series, daily PPP
troposphere estimates, transient earthquake data, and others. All new data productsets ingested and archived at the CDDIS will have a CMR collection record, CDDIS
landing page, and registered DOI;

Plans:•••

Enhance and update all collections metadata in EOSDIS Common Metadata Repository
with the guidance of the NASA IMPACT Analysis and Review of CMR (ARC) Project team;Continue work underway;

Standing Committee on Missions (Roland Pail/TUM, C.K. Shum/OSU)
Current Status and Progress:•

Activities were significantly hampered by pandemic;•

Evaluating contribution of current and near-term satellite missions to the GGOS 2020
goals;•••

Advocate the realization of future gravity field missions (see next slides (Joint
ESA/NASA activities (MAGIC, Joint science study with China)
e-.motion (ESA EE9; double pair);••

MOBILE (ESA EE10; high-low track;
NASA Mass Change Designated Observable (MCDO) study;•

ESA Next-Generation Gravity Mission (NGGM) study, MAGIC Phase A;

Contribute to set-up IAG Altimetry Service;

Plans:

ggos.org•

Set-up of a new concept of the Standing Committee to increase participation bypotential members;•

Work with the Coordinating Office to set up and maintain a Satellite Missions
Committee section on the GGOS website;•

Advocate and support national and international space agencies in their processes
towards future gravity missions, by providing material and taking part in studies that
support their realization;•

Continue exchange with PLATO on joint interests and possible collaborations;

October, 2021

14

Global Geodetic Observing System
GGOS Days 2021 - Report•

IERS Working Group on Site Survey and Co-locations (Ryan Hippenstiel/NGS)Current Status and Progress:•

Developing deflection of vertical (DoV) measurement capabilities utilizing a robotic total
station and camera, and conducted field testing for hopeful deployment on upcoming
local tie surveys;•

Examining new technologies and procedures for ground surveys at space geodesy
stations;• Encouraging more frequent site surveys and new survey groups to support the stations.
• Group continues to grow based on submissions to ITRF2020. New/updated colleagues
from Australia, New Zealand, and Spain have been added and contacts in Japan have been
provided.
• A full tie survey at GGAO will be conducted in Spring 2022 when the new SLR installation is
final.
Plans:

ggos.org•

Focus on gravity deformation of VLBI antennas;••

Examine new technologies and procedures for ground surveys at space geodesy stations;
Encourage more frequent site surveys and new survey groups to support the stations.

October, 2021

15

Global Geodetic Observing System
GGOS Days 2021 - Report
7.2 GGOS Bureau of Products and Standards
STATUS REPORT

28-09-2021

GGOS Bureau of Products and Standards
D. Angermann (1), T. Gruber (2), M. Gerstl (1), R. Heinkelmann (3), U. Hugentobler (2),
L. Sánchez (1), P. Steigenberger (4)(1)

Deutsches Geodätisches Forschungsinstitut, Technische Universität München (DGFI-TUM), Germany(2)

Institut für Astronomische und Physikalische Geodäsie (IAPG), Technische Universität München,
Germany(3)Helmholtz Centre Potsdam, German Research Centre for Geosciences (GFZ), Germany(4)

Deutsches Zentrum für Luft- und Raumfahrt (DLR), Oberpfaffenhofen, Germany

Present Status and ProgressThis report summarizes the present status and progress of the GGOS Bureau of Products and Standards(BPS), including the following GGOS components associated to the BPS:▪

Committee “Contributions to Earth System Modeling” (Chair: Maik Thomas)▪

Committee “Definition of Essential Geodetic Variables (EGVs)” (Chair: Richard Gross)▪

Working Group “Towards a consistent set of parameters for the definition of a new GRS”
(Chair: Urs Marti)

The BPS comprises the staff members, the chairs of the associated GGOS components, as well as
representatives of the IAG Services and other entities involved in standards and conventions.
In the framework of the renewing of the GGOS website, the BPS supports the GGOS Coordinating Officeregarding the representation of geodetic products. Two classifications for the products have been
implemented: The first option according to the geodetic themes provides the classical geodetic view,
whereas the second classification according to Earth system components and space may be preferred byusers from other disciplines. The GGOS website provides a unique information platform for geodetic dataand products, which should help to make them easier findable and more visible to other disciplines andsociety.
Furthermore, the BPS contributes to the re-writing of the IERS Conventions in the function as Chapter
Expert for the “General Definitions and Numerical Standards”. The director of the BPS serves as IAG
representative to ISO/TC 211 and UN GGIM “GGRF” Subcommittee on Geodesy (SCoG), mainly to theWorking Group “Data sharing and development of geodetic standards”. The BPS also contributes to theactivities of the Committee on Essential Geodetic Variables (EGVs) and to the two Working Groups on“DOIs for geodetic data” and “Towards a consistent set of parameters for the definition of a new GRS”.
ggos.org

October, 2021

16

Global Geodetic Observing System
GGOS Days 2021 - Report
Ongoing activities and planned actions▪

Act as contact and coordinating point for homogenization of IAG standards and products▪

Keep track of adopted geodetic standards and conventions across all IAG components, and initiate
steps to close gaps and deficiencies, and provide recommendations▪

Regularly update the BPS inventory on standards and conventions used for the generation of IAG
products to incorporate the latest developments in these fields▪

Contribute to the re-writing/revising of the IERS Conventions, mainly in the function as Chapter
Expert for Chapter 1 “General definitions and numerical standards“▪

Interact with external stakeholders in the field of standards and conventions (e.g., IAU, ISO,
CODATA, UN-GGIM, GGCE, ...)▪

Act as IAG representative to ISO/TC 211 and to the UN-GGIM Subcommittee on Geodesy (SCoG)
Working Group “Data Sharing and Development of Geodetic Standards”▪

Contribute to the GGOS components associated to the BPS and to the GGOS Working Group on
Digital Object Identifier (DOI) for geodetic data and products to improve their discoverability▪

Focus on the integration of geometric and gravimetric observations, and support the developmentof integrated products (e.g., GGRF, IHRF, atmosphere products)▪

Contribute to organizational and coordination issues within IAG/GGOS and with external entities▪

Contribute to the development of the renewed GGOS Website and to other GGOS outreachactivities (publications, popular articles, brochures, etc.).

▪

Present BPS activities and results at conferences and workshops, and publish them in scientificjournalsggos.org

October, 2021

17

Global Geodetic Observing System
GGOS Days 2021 - Report
STATUS REPORT

28-09-2021

GGOS Committee on Earth System Modeling
Maik Thomas
Helmholtz Centre Potsdam
GFZ German Research Centre for Geosciences
Present Status and Progress
Recent activities of the committee related to further developments of data assimilation and AI algorithms,
the explicit consideration of effects due to surface mass loading, and opportunities to provide realistic
model error estimates have been continued. Main foci were placed on:• Implementation of particle filter algorithms into stand-alone models and comparison withtraditional Kalman filter approaches;• Development and successful application of neural networks for downscaling of geodetic
observations (focus on terrestrial water storage systems derived from GRACE/GRACE-FO);• Consideration of lateral variations of the Earth’s structure in elastic and viscoelastic solid Earthmodels.
Furthermore, opportunities for the synergetic combination of newly developed methods based on artificial
intelligence with classical numerical model approaches have been discussed. However, this is a rather new
and complex development with strategic relevance also for environmental and climate system sciences
and will be an important topic for further investigations in the following years.
Planned Actions and Milestones
In the next year the activities will mainly concentrate on:•••

Continuation of feasibility studies to investigate opportunities of constraining dynamicallycoupled model systems by geodetic monitoring data;
Quality assessment of existing empirical and numerical ocean tide models in view of theirapplication in geodetic data processing; discussion of opportunities for theirimprovement;
Discussion and estimation of consequences of upcoming hardware developments for
CPU intensive model simulations (high-performance computing vs. exascale modeling).

ggos.org

October, 2021

18

Global Geodetic Observing System
GGOS Days 2021 - Report
GGOS Committee on Essential Geodetic Variables
Richard Gross (NASA Jet Propulsion Laboratory)
Present Status and Progress
The GGOS BPS Committee on Essential Geodetic Variables was established in 2018 in order to define a listof Essential Geodetic Variables and to assign requirements to them. Essential Geodetic Variables (EGVs)
are observed variables that are crucial (essential) to characterizing the geodetic properties of the Earthand that are key to sustainable geodetic observations. Examples of EGVs might be the positions ofreference objects (ground stations, radio sources), Earth orientation parameters, ground- and space-based
gravity measurements, etc. Once a list of EGVs has been determined, requirements can be assigned tothem. Examples of requirements might be accuracy, spatial and temporal resolution, latency, etc. These
requirements on the EGVs can then be used to assign requirements to EGV-dependent products like theterrestrial and celestial reference frames. The EGV requirements can also be used to derive requirementson the observing systems that are used to observe the EGVs. And the list of EGVs can serve as the basis
for a gap analysis to identify observations needed to fully characterize the geodetic properties of the Earth.
During GGOS Days 2017 it was agreed that a Committee within the GGOS Bureau of Products andStandards should be established in order to define the list of Essential Geodetic Variables and to assign
requirements to them. This Committee was subsequently established in 2018 and consists ofrepresentatives of the IAG Services, Commissions, Inter-Commission Committees, and GGOS Focus Areas.
Planned Actions and Milestones
The planned tasks of the Committee on Essential Geodetic Variables are to:•Develop criteria for choosing from the set of all geodetic variables those that are consideredessential;•

Develop a scheme for classifying EGVs;•

Within each class, define a list of EGVs;•

Assign requirements to each EGV;•

Document each EGV including its requirements, techniques by which it is observed, and point-ofcontact for further information about the EGV;•

Perform a gap analysis to identify potential new EGVs;•

Define a list of geodetic products that depend on each EGV;•

Assign requirements to the EGV-dependent products;•

Hold workshops to engage the geodetic community in the process of defining EGVs, determining
their dependent products, and assigning requirements to them.

ggos.org

October, 2021

19

Global Geodetic Observing System
GGOS Days 2021 - Report
STATUS REPORT

29-09-2021

GGOS WG “Towards a consistent set of parameters for the definition of a new GRS"
Urs Marti
Federal Office of Topography swisstopo, Wabern, Switzerland

Present Status and Progress
The main task of this WG is to define a consistent set of parameters and formulas for the definition of a
new conventional Global Reference System (GRS). This includes the geometry (size and shape of areference ellipsoid), the gravity field (normal gravity field of this ellipsoid), physical heights, terrestrial timeand Earth rotation.
This new definition becomes necessary because since the introduction of GRS80 (Moritz, 1980) the
knowledge in Geodesy has improved a lot (e.g. GNSS, gravity space missions) and the use of theparameters became inaccurate and inconsistent over time. The problem of the permanent Earth Tide was
not yet a topic at the epoch of the definition of GRS80. A new set of parameters was published by Groten
in 2004 but was not widely introduced in Geodesy. Another source of parameters are the IERS conventions,which do not strictly apply GRS80.
The acceptance of the IAG Resolution Nr. 1 in 2015 which defines the potential at Sea Level (W0) evenincreases the inconsistency in the geodetic parameters of the conventional GRS (in GRS80, W0 is a derived
quantity).
The new set of parameters is based on the four fundamental parameters: W0 (Potential at Reference
Level), J2 (dynamic form factor, “flattening”), GM (geocentric gravitational constant) and ω (angularvelocity of the Earth). All these quantities are well observed and monitored by various geodetic spacetechniques. (This implies, that the semi major axis of the ellipsoid will be a derived parameter).
Most of the defining parameters change with time. This includes seasonal variations and long-term trends.
These changes are important and must be considered for the consistency with the ITRF (e.g. ellipsoidal
heights). Nevertheless, in order to keep things simple for the user, this time variability will not be treatedin the published definition of a new GRS. All quantities will be fixed to the epoch 2010.0. This is the epoch
at which the W0 of the IAG resolution Nr. 1 is defined.
All calculations will be done in the zero tide system. Only at the very end, conversion formulas to meantide and tide-free will be given for all quantities. In order to keep things simple, some very minor terms inthis conversion will be neglected.
Planned Actions and Milestones
A draft of the paper with the calculation of the parameters is available. It has to be finished and discussed
in the WG. It follows more or less the structure of the papers by Moritz (1980) and Groten (2004).

ggos.org

October, 2021

20

Global Geodetic Observing System
GGOS Days 2021 - Report
The calculation of a new set of parameters is one thing. The main problem will be to convince the users to
adopt such a system as a new global reference. Many users don’t see the necessity to replace GRS80, as
they just see it as a conventional model for the conversion of geocentric coordinates or for the calculationof gravity anomalies. Main concerns are the danger of confusion and the necessity to update many
software packages. This discussion has still to be lead.
Another question to be answered is the necessity to define a conventional global gravity field model. For
many applications (e.g. global height system, reference for local geoid determination), the assignment ofsuch a standard model would have some advantages. For different application we would need a lowresolution satellite-only model and a high-resolution combined model.

ggos.org

October, 2021

21

Global Geodetic Observing System
GGOS Days 2021 - Report
7.3 GGOS Focus Area Unified Height System (FA-UHS)STATUS REPORT

2021-09-01

GGOS Focus Area Unified Height System (FA-UHS)
Laura Sánchez
Deutsches Geodätisches Forschungsinstitut, Technische Universität München (DGFI-TUM)
Present Status and Progress
The GGOS Focus Area “Unified Height System” (GGOS-FA-UHS, formerly Theme 1) was establishedat the 2010 GGOS Planning Meeting (February 1 - 3, Miami, Florida, USA) to lead and coordinate
the efforts required for the establishment of a global unified height system that serves as a basis
for the standardisation of height systems worldwide. Starting point was the results delivered by the
IAG Inter-Commission Project 1.2 Vertical Reference Frames (IAG-ICP1.2-VRF), which was operativefrom 2003 to 2011. During the 2011-2015 term, different discussions focussed on the best possible
definition of a global unified vertical reference system resulted in the IAG resolution for the
Definition and realisation of an International Height Reference System (IHRS) that was approved
during the 2015 General Assembly of the International Union of Geodesy and Geophysics (IUGG) in
Prague, Czech Republic. In the term 2015-2019, actions dedicated to investigate the best strategy
for the realisation of the IHRS (i.e., the establishment of the International Height Reference Frame– IHRF) were undertaken. In particular, a preliminary station selection for the IHRF reference
network was achieved and different computation procedures for the determination of potential
values as IHRS coordinates were evaluated.
At present, we are preparing a special issue on Reference Systems in Physical Geodesy to be
published in the Journal of Geodesy. This special issue includes the scientific description of the best
available strategies for the geoid modelling as well as key contributions for the establishment of
the IHRS/IHRF and the IGRS/IGRF (International Gravity Reference System and Frame). Paper
submission started in October 2019 and was closed in May 2020. We received 22 manuscripts; 18of them are already published, two were rejected, and the other two are still under review.
A recent milestone is the publication of an extensive guideline for the realisation of the IHRS,
including:-

Strategy for the appropriate handling of permanent tide effects in the determination of
IHRF coordinates in the mean-tide system-

Strategy for the determination and evaluation of IHRF coordinates depending on the data
availability (specially surface gravity data and topography models)-

Strategy to improve the input data required for the determination of IHRF coordinates-

Strategy for the IHRF station selection in regional and national densifications-

Strategy to ensure the usability and long-term sustainability of the IHRF

ggos.org

October, 2021

22

Global Geodetic Observing System
GGOS Days 2021 - Report
The authors of this paper represent the main IAG entities working on physical height systems andgeoid modelling: GGOS FA-UHS, IAG Commission 2, IAG ICCT, IGFS:
Sánchez L., Ågren J., Huang J., Wang Y.M., Mäkinen J., Pail R., Barzaghi R., Vergos G.S., Ahlgren K.,
Liu Q.: Strategy for the realisation of the International Height Reference System (IHRS). Journal of
Geodesy, 95(3), 10.1007/s00190-021-01481-0, 2021
Planned Actions and Milestones
The planned activities of the FA-UHS may be summarised as follows:(1) Based on the procedure described by Sánchez et al. (2021), to coordinate with regional/national
experts in gravity field modelling the computation of a first IHRF solution;(2) To refine standards, conventions, and guidelines to support a consistent determination of the IHRF
at regional and national levels;(3) With the support of the IAG Commission 2, the International Gravity Field Service (IGFS) and theInter-Commission Committee on Theory (ICCT) to promote the study of quality assessment in thedetermination of potential values and determination of potential changes with time. In this way,following working/study groups play a main role to achieve the GGOS-GA-UHS objectives:-

IAG Commission 2 working group Error assessment of the 1-cm geoid experiment, chaired by T
Jiang (China) and VN Grigoriadis (Greece).
IAG ICCT study group Geoid/quasi-geoid modelling for realisation of the geopotential heightdatum, chaired by J Huang (Canada) and YM Wang (USA).
GGOS-FA-UHS and IGFS working group Implementation of the International Height Reference
Frame (IHRF), chaired by L Sánchez (Germany) and R Barzaghi (Italy).

(4) In agreement with the IGFS and the IAG Commission 2, to design a strategy to install an operational
infrastructure within the IGFS to ensure the maintenance and availability of the IHRF in a long-termbasis. Aspects to be considered are:--ggos.org

Updates of the IHRS definition and realisation according to future improvements in geodetic
theory and observations.
Regular updates of the IHRF according to new stations, coordinate changes with time,
improvements in the estimation of reference coordinates and modelling of the Earth’s gravity
field, etc.
Support in the realisation and utilisation of the IHRS/IHRF at regional and national level.
To guarantee an organisational and operational infrastructure to ensure the sustainability of
the IHRF.

October, 2021

23

Global Geodetic Observing System
GGOS Days 2021 - Report
7.4 GGOS Focus Area Geohazards
STATUS REPORT

2021-10-13

GGOS Focus Area Geohazards
John LaBrecqueCenter for Space Research, University of Texas at Austin
Present Status and Progress
The Geohazards Focus Area is working to support the IUGG 2015 Resolution #4 as discussed andreported upon by the GTEWS 2017 workshop. The GTEWS 2017 Workshop Report is the peer reviewed
version of the initial report by the APRU. The Focus Area activities implement the GGOS 2020
recommendation 5.8 to “promote the development of GNSS seismology particularly for early warningand disaster assessment”.
The Focus Area fully supports the GATEW Working Group that is aligned to these same goals via a call forparticipation. The GATEW Working Group was formed in response this call for participation issued by the
GGOS Chair (Dr. Kutterer). The GATEW WG currently numbers 18 exceptional institutions from 12
countries. The GATEW WG was central to the success of the GTEWS 2017 workshop. The current
pandemic crisis impacted the Geohazards Focus Area. This Focus Area had announced the GTEWS 2020
meeting as a sequel to GTEWS 2017. GTEWS 2020 was a collaboration with the IUGG, APRU, Tohoku
University, UCDAVIS. 2020 Planning and preparations for GTEWS Principals Organizational Meeting –theongoing pandemic imposed delay is being used to further develop the community vision. Current
planning is for a meeting of Principals during the Fall of 2022.
Planning is underway for a Meeting of Principals to begin the review and the interim, we determinedthat it is best to move forward with the first recommendation of the GTEWS 2017 workshop i.e., theestablishment of a Consortium to oversee the development and operation of a GNSS enhancement to
Tsunami Early Warning for the Indo-Pacific and Caribbean Basins. Starter funds have been identified insupport of a meeting of principals to develop a GTEWS Consortium to encourage the shared use of realtime multl-GNSS data and processing software within cloud computing environment. It is believed that
rapid progress can be made with minor investment.
The concept of a meeting of principals to discuss the GTEWS Consortium is endorsed by the GGOS
Coordinating Committee, the IAG President, the IUGG Commission on Geophysical Risk andSustainability.
The GEO workplan for 2020-2022 establishes the Geodey4Sendai Community Activity. Geodesy4 Sendai
is the optimal forum for the GTEWS Consortium. I am working with Allison Craddock to recommend that
GEO include the GTEWS_Consortium as a community activity within the Geodesy4Sendai initiative. The
IUGG has offered about $20,000 in support of this meeting. These funds will serve as starter funds inplanning the meeting of principals to include a broadened support community of agencies andinstitutions.
Planned Actions and Milestones
During the coming months, the GATEW Working Group will conduct virtual meetings with small
subgroups to discuss support for GTEWS Consortium its goals, strategies, timelines and membershipcomposition including those government agencies responsible for disaster risk management.

ggos.org

October, 2021

24

Global Geodetic Observing System
GGOS Days 2021 - Report
7.5 Focus Area: Geodetic Space Weather Research
STATUS REPORT

29.09.2021

Focus Area: Geodetic Space Weather Research
Michael Schmidt (1), Ehsan Forootan (2)(1) Deutsches Geodätisches Forschungsinstitut der Technischen Universität München (DGFI-TUM),
Germany, mg.schmidt@tum.de(2) Geodesy and Earth Observation Group, Aalborg University, Denmark, efo@plan.aau.dk
Present Status and Progress
The following items should be mentioned here:•

Following the decision made at the splinter meeting of the FA-GSWR at the IUGG 2019 General
Assembly in Montreal, the scientific content of the FA-GSWR was officially extended by themagnetosphere and their coupling processes such that the FA deals with the Magnetosphere –Ionosphere and Plasmasphere – Thermosphere (MIT) system and the mutual couplings.

•

One single GGOS Joint Study Group (JSG), associated with the Inter-Commission Committee on
Theory (ICCT) of the IAG and denoted as ICCT-JSG T 0.27, and three Joint Working Groups (JWG),
directly associated with the FA-GSWR, have been implemented within the FA-GSWR.

•

Setup and performance of the Session G5.1 “Ionosphere, thermosphere and space weather:monitoring and modelling” within the Geodesy Division at the virtual EGU 2021 General
Assembly, April 19 to 30, 2021. Several presentations in this session have been given by membersof the JSG and JWGs of the FA-GSWR. The convener of the session was Ehsan Forootan, Michael
Schmidt a co-convener.

•

Performing a joint virtual splinter meeting with the chairs and vice-chairs of the working groupsof the Sub-Commission 4.3 “Atmosphere Remote Sensing” of IAG’s Commission 4 “Positioning
and Applications” and the chairs and vice-chairs of the JSG and the JWGs of the FA-GSWR at April
26, 2021 on the status and the future steps of the FA-GSWR.

•

Setup and performance of the Session 5.4 “Geodetic Space Weather Research” within the
Symposium 5 “Global Geodetic Observing System (GGOS): the metrological basis for themonitoring” at the virtual IAG 2021 Scientific Assembly, Beijing, China, June 28 to July 2, 2021.
The session consisted of an oral part with 6 presentations and a poster part with 7 additional eposters. The convener of the session was Michael Schmidt, Ehsan Forootan a co-convener.

•

The JSG and the JWGs of the FA-GSWR have achieved the following important results and haveacquired noteworthy knowledge during the reporting period:ggos.org

October, 2021

25

Global Geodetic Observing System
GGOS Days 2021 - Report
JSG 1 (ICCT-JSG 0.27) “Coupling processes between magnetosphere, thermosphere andionosphere electron density modelling”; Chair: Andres Calabia Aibar (China), Vice-Chair:
Munawar Shah (Pakistan), Research Coordinator: Binod Adhikari (Nepal), 17 groupmembers
Current activities: (1) working through a common platform to increase thecommunication and to prepare a spreadsheet with interests of each group member, (2)increase international cooperation to break the existing isolation, (3) elaboration of a
proposal for an International workshop on MIT Coupling (IWMTIC2021): Prospects,
Challenges, and Opportunities in Kathmandu, Nepal, 2022,
More information on the activities of JSG 1 can be found at the website:
https://www.researchgate.net/project/IAG-JSG1-Coupling-processes-betweenmagnetosphere-thermosphere-and-ionosphere-MTI
JWG 1 “Electron density modelling”; Chair: Fabricio dos Santos Prol (Germany), Vice-Chair:
Alberto Garcia-Rigo (Spain), 18 group members
Current activities: (1) provision of the final results of the first campaign regarding theaccuracy of ionospheric models using a fair database, (2) creation of a simulated casescenario to perform the second campaign of data quality evaluations.
JWG 2 “Improvement of thermosphere models”; Chair: Christian Siemes (The Netherlands), ViceChair: Kristin Vielberg (Germany), 9 group members
Current activities: virtual group meeting in September 2021, (1) ongoing data and modelcomparison of accelerometer-derived mass densities, (2) planned comparison of PODderived mass densities
JWG 3 “Improved understanding of space weather events and their monitoring by satellite
missions”; Outgoing Chair: Alberto Garcia-Rigo (Spain; till 30th September, 2021),
Incoming Chair: Haixia Lyu (China; from 1st October, 2021) Vice-Chair: Benedikt Soja
(Switzerland), 11 group members
Current activities: (1) correlation between space weather products and perturbed
ionospheric electron density or VTEC, jointly performed with JWG 1, (2) a set of four
historical representative space weather events were selected to be analyzed, includingstorm-related periods in 2013, 2015, 2017 and 2018, performed together with JWG 1.
•

During the Corona pandemic and the related lockdowns many papers have been written in thereporting period on topics related to the JSG and the JWGs of the FA-GSWR.

•

In the same manner significant progress has been made in third-party funded national andinternational projects, which are often strongly coupled to the objectives of the JGS and the JWGs
of the FA-GSWR.

ggos.org

October, 2021

26

Global Geodetic Observing System
GGOS Days 2021 - Report
Planned Actions and Milestones•

Continuation of the work on the definition and selection of the essential geodetic variables (EGV)in the framework of the scientific work within FA-GSWR.

•

The main topics of the FA-GSWR are again included in the description of the PICO Session G5.1:
Ionosphere, thermosphere and space weather: monitoring and modelling of the Geodesy Divisionof the European Geosciences Union (EGU) General Assembly (GA) 2022. The main convener of thissession will be Ehsan Forootan, co-conveners of the Session G5.1 are Benedikt Soja, Kristin Vielberg
and Michael Schmidt. Deadline for submitting abstracts will be January 12, 2022; the EGU GA 2022
will take place from April 3 to 8, 2022 in Vienna, Austria.

•

Planning of a splinter meeting of the FA-GSWR during the EGU GA 2022 in Vienna.

•

The 2nd International Symposium of IAG Commission 4 “Positioning and Applications” wasoriginally planned for September 7 – 11, 2020 with a special conference part dedicated andorganized by the FA-GSWR; due to the Corona pandemic the symposium was postponed to
September 2022.

•

JSG 1 as a part of the ICCT (Inter Commission Committee on Theory) will organize a session at the2022 Hotine-Marussi symposium.

ggos.org

October, 2021

27