Bureau Gravimétrique International
International Gravimetric Bureau
a scientific service of
International Association of Geodesy (IAG)
International Gravity Field Service (IGFS)
International Union of Geodesy and Geophysics (IUGG)
BGI is the scientific service of the International Association of Geodesy (IAG) aimed at ensuring the data inventory and the long term availability of the gravity measurements acquired at the Earth’s surface. Its main task is the collection, validation and archiving of gravity data and products from relative or absolute gravity surveys and their diffusion to a large variety of users for scientific purposes. Read more…
Data, products or software available at BGI are mostly dedicated for supporting scientific and academic activities. The national agencies and scientists interested for contributing with their absolute or relative gravity data (field, marine or airborne surveys) to the update of the global knowledge of the Earth’s gravity field and to the new International Gravity Reference Frame (IGRF) are encouraged to contact us. Read more…
Data & Products
GRIDS & MODELS
International Gravity Reference System & Frame (IGRS/IGRF)
The International Gravity Reference System & Frame (IGRS/IGRF) aims at providing a global and long term gravity reference based on absolute and traceable gravity measurements such as provided by the state-of-the-art of absolute gravity meters (corner cube or cold-atoms). This international project has been launched in 2017 through the IAG Joint Working Group JWG 2.1.1 (Chair : H. Wziontek [BKG] ; Co-Chair : S. Bonvalot [BGI]).
The IGRS/IGRF includes :
- a primary global network of gravity reference stations that will provide an accurate and long term absolute monitoring of the gravity field at selected stations where the gravity can be monitored continuously at the microGal level (10-8 m.s-2). This network, possibly in collocation with other geodetic techniques, should contribute to the infrastructure of IAG/GGOS Core sites. The target accuracy of this reference network, based on high precision measurements, is at few µGal level.
- a secondary global network of gravity sites determined from field or laboratory absolute gravity measurements that will provide absolute gravity values for referencing relative land, marine or airborne surveys, or for calibrating relative instruments. This secondary network must be considered as a replacement of the existing IGSN71 network which is still the official global reference. The target accuracy for this secondary network is within few to few tens of µGal. The key contribution for this global network, is expected to come from worldwide agencies in charge of the national geodetic infrastructures.
See more details in Wziontek et al. (Journal of Geodesy, 2020)
Activities & Projects
DEFINITION OF STANDARDS
BGI contributes within IAG, and its components GGOS, Commission 2 “Gravity Field” and IGFS to several activities and Joint Working Groups (JWG) aimed at improving the global knowledge and accuracy of the Earth gravity such as :
- The realization of the International Gravity Reference System & Frame (IAG JWG 2.2.1)
- The definition of United formats and processing software for high-precision gravimetry (IAG JWG 2.2.1)
- The evaluation of Novel sensors and quantum technology for Geodesy (IAG JWG QuGe)
BGI contributes to the evaluation of new gravity sensors based on cold-atom technologies such as (i) the first commercial Absolute Quantum Gravimeter (AQG) developed by MuQuans company (France) and (ii) the Absolute Quantum Gravimeter GIRAFE designed by ONERA (France) for moving platform. This activity also directly contributes to the new IAG Working Group “Novel Sensors and Quantum Technology for Geodesy (QuGe)” and more specifically to its sub-working group “Quantum gravimetry in space and ground”.
BGI associated teams also contribute to the realization of gravity surveys and networks in the frame of national or international research projects with national agencies.
- FR-IGN : French Absolute Gravity network
- FR-RESIF : French seismological and geodetic network
- GEOMED-II Project : A new geoid for Mediteranean sea
- ALP-ARRAY Project : A new Bouguer anomaly for European Alps