Definition of gravity standards & networks
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 :
- International Gravity Reference System & Frame (IAG JWG 2.2.1)
- United formats and processing software for high-precision gravimetry (IAG JWG 2.2.1)
- Novel sensors and quantum technology for Geodesy (IAG JWG QuGe).
INTERNATIONAL GRAVITY REFERENCE SYSTEM (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)