Why & how to contribute to BGI ?

As the international scientific service of IUGG and IAG/GGOS, the BGI’s ultimate task is to provide a secure archive of gravity observations, and to give the wider scientific community access to relative and absolute measurements of the Earth’s gravity field and related information.

The permanent archiving of new gravity data sets is essential to improve the coverage and accuracy of the global gravity database, and our knowledge of the Earth’s gravity field. It also enables the BGI to validate gravity observations within a global reference framework, and to return them in standard, unified formats useful to the various users, thus enhancing the realization of future global models of the Earth’s gravity field and the establishment of an international gravity reference framework. The contribution of agencies and institutions involved in the acquisition of relative or absolute gravity data is welcome to ensure the best possible service to the community.

BGI currently collects, archives & provides information on:

• Relative and absolute gravity measurements (from land, marine & airborne surveys)
• National or regional gravity reference networks
• Other gravimetry-related information (bibliography, software…)

The national agencies and scientists whishing to contribute to the archiving of their gravity observations and to the updating the global knowledge of the Earth’s gravity field are invited to contact us.

Contact : bgi@cnes.fr

Public or restricted data & products ?

Data, products or software available at BGI are primarly intented to support scientific and academic activities. Their diffusion to public or academic users is then encouraged through the BGI. Nevertheless, the BGI will ensure and maintain the level of confidentiality of data and products in accordance with the whishes of the suplying institutions.

Data, products and software remain the property of the institution that provided them. All types of relative gravity measurements (from terrestrial, marine or airborne surveys) and absolute measurements can be archived at the BGI. For most relative measurements, the acquisition files containing the original observations downloaded from the instrument are not collected. Therefore, only the final data set containing the processed and corrected observations for the entire survey is expected (see Data and Formats section). For absolute gravity measurements, the greater the number of acquisition files provided, the better. For example, observation files such as the “project” file (mandatory) and the “set”, “drop”, and “gsf” files (strongly recommended) derived from the Micro-g LaCoste “g” software and commonly used for FG5 and A10 observations, are expected.

A level of confidentiality that restricts redistribution, and possibly a level of accuracy, may be specified by the contributing institutions (see below).

Confidentiality Level	Relative mesurements	Absolute measurements
0	Information displayed : none Data distribution : none Purpose : Archiving only	Information displayed : none Data distribution : none Purpose : Archiving only
1	Information displayed : Location of measurements (from the given geographical coordinates) ; Name of institution for contact by potential users Data distribution : none Purpose : Archiving and public display of Metadata data for further direct contacts by interested users	Information displayed : Location of measurements (from the given geographical coordinates) ; Name of institution for contact by potential users Data distribution : none Purpose : Archiving and display of Metadata data for further direct contacts by interested users
2	Information displayed : Location of measurements (from the given geographical coordinates) ; Name of institution for contact by potential users ; All other information provided for diffusion on the data acquisition and processing Data distribution : Possible (with DOI) if authorized by the supplying institution. Purpose : Archiving and public display of Metadata data for further direct contacts by interested users ; Diffusion of data according to the proprietary policies	Information displayed : Location of measurements (from the given geographical coordinates) ; Name of institution for contact by potential users ; All other information provided for diffusion on the data acquisition and processing Data distribution : Possible (with DOI) if authorized by the supplying institution. Purpose : Archiving and display of Metadata data for further direct contacts by interested users ; Difusion of data according to the proprietary policies Note : The supplying institutions or contriburors are invited to provide a precision threshold on the public display of their gravity observations (i.e. 1, 10 , 100, 1000 µGal)

DOI referencing

Datasets & products archieved at BGI benefit from DOI referencing.