SC 2.1: Terrestrial gravimetry for the needs of geosciences andmetrology
Chair: Przemysław Dykowski (Poland)
Vice-Chair: Ezequiel Antokoletz (Argentina/Germany)
Terms of Reference
Geodesists, geophysicists as well as the metrological community utilize gravity datasets from a wide variety of sources: local relative gravity campaigns, pointwise absolute gravity observations, gravity variations in time at fixed locations, and regional scale observations from marine and airborne platforms. These observations need to be consistent with each other, consistent with satellite-based results, and have well defined accuracy/uncertainty determinations. IAG Sub-commission 2.1,“Terrestrial gravimetry for the needs of geosciences and metrology” aims to bring together scientists from all over the globe that are interested in the instruments, techniques, and analysis of terrestrial, marine and airborne gravity measurements.
Objectives
The Sub-Commission 2.1 will:
- Provide the scientific community with the means to assess the accuracy of their collected gravity datasets with respect to the international gravity reference standards maintained through absolute gravity observations and the organization of regular international absolute gravimeter comparisons. These efforts are done in close cooperation with the metrology community: the BIPM Consultative Committee onMass and Related Quantities, its Working Group on Gravimetry (CCM-WGG), and other Regional Metrology Organizations as well as all interested scientific institutions. This relationship allows for direct traceability of gravity data to international standards between the geoscience and metrology communities.
- Support the dissemination of the results of these activities through an international absolute gravity database, which in turn, will support the ongoing realization of a new and improved International Terrestrial Gravity Reference Frame (ITGRF), as a realization of the International Terrestrial Gravity Reference System (ITGRS) defined by the IAG in its Resolution adopted during the IUGG General Assembly 2023 (https://www.iag-aig.org/doc/651bd7f2e3cbf.pdf).
- Support sharing expertise and experience in performing gravity surveys on moving platforms (Marine, Airborne) allowing for the collection of the highest possible quality gravity data using the most up-to-date techniques and, at the same time, allowing the assessment of achieved accuracies.
- Promote research and development into new instruments and techniques by stimulating communication, cooperation as well as knowledge dissemination between scientific groups worldwide. The Sub-commission will encourage regional meetings and dedicated workshops to face specific problems when and where appropriate.
Program of Activities
- Appoint the Steering Committee consisted of experienced members related to the activities of SC2.1 and the contact persons for European, East Asia, Western Pacific,South America and North America Gravity Networks.
- Host the SG2.1.1 “Developments in near Earth gravity measurements on moving platforms”.
- Support IAG Commission 2 Symposia such as GGHS as well as any gravity-related meetings.
- Support of the ITGRF with a database for absolute gravity observations and the documentation of results from the comparisons of absolute gravimeters.
- Support the activities of the Working Group Q.1: Quantum gravimetry in spaceand on ground of the IAG Project – Novel Sensors and Quantum Technology forGeodesy (QuGe).
Steering Commitee
- Przemysław Dykowski (Poland); Chair
- Ezequiel Antokoletz (Argentina/Germany); Vice-Chair
- John Crowley (Canada)
- Jack McCubbine (Australia)
- Shuqing Wu (China)
- Derek van Westrum (USA)
- Sylvian Bonvalot (France)
- Hartmut Wziontek (Germany)
- Mirjam Biker-Koivula (Finland)
- David Avalos (Mexico)
- Iuri Bjorkstrom (Brasil)
- Thapelo Mametja (South Africa)
- Takahito Kazama (Japan)
- Leni Sophia Heliani (Indonesia)
Working Groups of Sub-Commission 2.1
JWG 2.1.1: Development of the International Terrestrial Gravity Reference Frame
(joint with IGFS, BGI, IGETS)
Chair: Hartmut Wziontek (Germany)
Vice-Chair: Sylvain Bonvalot (France)
Terms of Reference
One task of IAG’s Commission 2 “Gravity Field” is the establishment of the International Terrestrial Gravity Reference System and Frame (ITGRF). These activities are motived by the IAG Resolutions No. 2 of 2015 (IUGG General Assembly Prague), No. 4 of 2019 (IUGG General Assembly Montreal) and No. 1 of 2023 (IUGG GeneralAssembly Berlin). The IAG Sub-Commission 2.1 “Terrestrial gravimetry for the needs of geosciences and metrology” promotes consistency and compatibility of gravity and gravity gradient datasets and assessment of their accuracy. The International Gravity Field Service (IGFS) coordinates the servicing of the geodetic and geophysical community with gravity field related data, software and information. The infrastructure of IGETS, specifically stations operating superconducting gravimeters, provides a basis for reference stations of the ITGRF. The ITGRF as a modern and precise absolutegravity reference frame will not only contribute to the establishment of the Global Geodetic Reference Frame (GGRF) of the UN, but will also serve as a long-term and precise gravity reference for the IAG Global Geodetic Observing System (GGOS).
Objectives
- Within IAG Sub-Commission 2.1 “Terrestrial gravimetry for the needs of geosciences and metrology” the realization of the International Terrestrial Gravity Reference Frame (ITGRF) will be continued. The ITGRF is the realization of the International Terrestrial Gravity Reference System (ITGRS). According to IAG Resolution No. 1 of 2023, the ITGRS is defined by the observation of the instantaneous acceleration of free fall, the traceability of these observations to the International Systemof Units (SI), and a set of conventional corrections for the time independent components of gravity effects. The ITGRF as the realization of the ITGRS is based on observations with absolute gravimeters (AG) which are monitored at reference stations, and during comparisons. The ITGRF further recommends a set of conventional models for the correction of temporal gravity changes. Finally, the ITGRF demands a compatible infrastructure accessible to end-users, as expressed by IAG Resolution No. 4 of 2019.
- The JWG focuses on the establishment of such infrastructure in cooperation with IGFS, GGOS, international and national institutions, agencies, and governmental bodies. This infrastructure should consist of reference stations on the national level for the monitoring of AGs. On the international level, comparison stations will provide the facilities to check the compatibility of AGs, and core stations will link to space geodetic techniques (ITRF) and the International Height Reference Frame (IHRF).
- The absolute gravity database “AGrav” which is a permanent component of the International Gravimetric Bureau (BGI) services will be developed to a central inventory to document all ITGRF stations and related AG observations.
- A close cooperation with the International Geodynamics and Earth Tide Service (IGETS) supports the continuous monitoring at the gravity reference stations. The collaboration with the Working Group on Gravimetry of the Consultative Committee on Mass and Related Quantities (CCM-WGG) at BIPM establishes a link to metrology and supports the traceability of the AG observations.
- The activities should be further aligned with the JWG on the Implementation of the International Height Reference Frame.
Members
Hartmut Wziontek (Germany); Chair
Sylvain Bonvalot (France); Vice-Chair
Mauro Andrade de Sousa (Brazil)
Ezequiel Antokoletz (Germany)
Mirjam Bilker Koivula (Finland)
John Crowley (Canada)
Przemysław Dykowski (Poland)
Andreas Engfeldt (Sweden)
Alessandro Germak (Italy)
Jaakko Mäkinen (Finland)
Urs Marti (Switzerland)
Jack McCubbine (Australia)
Vojtech Palinkas (Czech Republic)
Victoria Smith (UK)
Ludger Timmen (Germany)
Claudia Tocho (Argentina)
Christian Ullrich (Austria)
Derek van Westrum (USA)
Shuqing Wu (China)
Koji Matsuo (Japan)
Arturo Villar García (Spain)
Corresponding Members
Jonas Ågren (Sweden)
Daniel Barnes (USA)
Henri Baumann (Switzerland)
Denizar Blitzkow (Brazil)
Jean-Paul Boy (France)
Ana Cristina O. Cancoro de Matos (Brazil)
In-Mook Choi (Korea)
Neda Darbeheshti (Australia)
Renaud Degoy (France)
Alfredo Esparza (Mexico)
Alessio Facello (Italy)
Germinal Gabalda (France)
Walter Humberto Subiza Piña (Uruguay)
Domenico Iacovone (Italy)
Shuanggen Jin (China)
Janis Kaminskis (Latvia)
Jeff Kennedy (USA)
Márta Kis (Hungary)
Martin Lederer (Czech Republic)
Camilo Matiz (Colombia)
Leidy Johanna Moisés Sepúlveda (Colombia)
Per-Anders Olsson (Sweden)
Tomasz Olszak (Poland)
Andrea Prato (Italy)
Rene Reudink (Netherlands)
Laura Sanchez (Germany)
Heping Sun (China)
V.M. Tiwari (India)
SG 2.1.1: Developments in near Earth gravity measurementson moving platforms
Chair: Derek van Westrum (USA)
Vice-Chair: Neda Darbeheshti (Australia)
Terms of Reference
Developments in gravity and gravity gradiometry measurements from (non-satellite) moving platforms continue at a rapid pace. Alongside conventional spring-based systems, sensors now include micro-electromechanical systems (MEMS), inertial measurement units (IMUs), and quantum absolute instruments. In addition to ships and fixed-wing aircraft, mobile platforms now include a wide range of drones (airborne, seaborne, and underwater). Proposals are even underway for optical clock deployments on moving platforms. SG 2.1.1 is focused on tracking all aspects of these developments: sensors, platforms, platform integration, analysis techniques, survey projects, and data applications.
Objectives
- Communication between the gravity science community and the institutes, research groups, and companies that are developing novel instruments and deployments.
- Coordination of scientific efforts and best practices regarding the collection and analysis of mobile platform gravity data.
- Promotion and coordination of mobile gravity datasets for the establishment of regional gravity networks and other applications.
- Organization of scientific workshops and meetings for the discussion of techniques and methods of mobile gravity measurements.
Members
Derek van Westrum (USA); Chair
Neda Darbeheshti (Australia); Vice-Chair
Jack McCubbine (Australia)
Tao Jiang (China)
Tim Jensen (Denmark)
Christoph Forste (Germany)
Masahiro Nakashima (Japan)
Koji Matsuo (Japan)