Data formats and definitions

Data formats and definitions

BGI is the official IAG/GGOS service hosting the global gravity databases for relative and absolute gravity measurements.

The relative gravity database has been set up since the 1950’s from the compilation of the data provided with the support of many contributing institutions worldwide and contains nowadays over 12 millions of observations from land, marine and airborne gravity surveys.

The absolute gravity database (AGrav) has been set up in 2008 in joint cooperation between BGI and BKG (Bundesamt für Kartographie und Geodäsie, Germany) and is the reference database for the International Terrestrial Gravity Reference System & Frame (ITGRS/ITGRF).

Relative and absolute gravity observations are archived with the available information provided by the supplying institutions about station coordinates, gravity measurements and accuracies, gravity corrections, systems, etc. (see formats below).

Contributors interested in updating the BGI databases with relative or absolute gravity measurements as public or proprietary data are invited to contact BGI. Data will be archived at BGI according to the distribution policies defined by the contributing institutions. Contact :

  • Wziontek H., Bonvalot S., Falk R., Gabalda G., Mäkinen J., Palinkas V., Vitushkin L. (2021). Status of the International Gravity Reference System and Frame. Journal of Geodesy, 95:7,
  • Wziontek, H., Wilmes, H., Bonvalot, S. “AGrav – An International Database for Absolute Gravity Measurements“. IAG Proceedings series. AGrav_Wziontek_etal2.pdf 530.32 kB
  • Wilmes, H., Wziontek, H., Falk, R., Bonvalot, S. “AGrav—The New International Absolute Gravity Database of BGI and BKG and its benefit for the Global Geodynamics Project (GGP)”. Journal of Geodynamics 48 (2009) 305–309.
  • Land gravity data format (EOL) / Sea gravity data format (EOS)
    BGI_EOL_EOS_Data_format.pdf 169.60 kB
  • Fortran routine to extract [Longitude / Latitude / Bouguer] fields from EOL data file
    conveol2xyz.pdf 6.24 kB
  • Geodetic reference system : WGS84
  • Gravity reference system : IGSN71
  • Geoid reference system : EGM2008
  • Height reference system : Elevation (orthometric height above sea level)