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AMPERE Virtual Geomagnetic Observatory (VGO) Higher Level Data Products

These data are derived estimates of the departures of the Earth's magnetic field at 780 km altitude relative to the International Geophysical Reference Field, generation 11 (IGRF-11, Finlay et al., 2010) magnetic field reference model. These estimates were derived from Iridium satellite magnetic field observations as described in Anderson et al. (2021) which should be studied before using these high-level data. Each file consists of the magnetic field difference relative to IGRF-11 at 780 km attitude for each geographic latitude and longitude entry in the file. The magnetic field is given in spherical polar coordinates, radial, polar angle (theta) increasing southward, and azimuth (phi) increasing eastward. The dates for which these VGO results are provided are selected to be the quietest set of days within each month and quarter as described in Anderson et al. (2021). These results do not preserve the magnitude of the main field as the data processing applies an inter-calibration of the observations against IGRF-11, but apart from this calibration scale factor, the results reflect the true geometry of the geomagnetic field. When using these data for publications of research analysis, please cite Anderson et al. (2021) and follow the rules of the road guidelines for AMPERE data products given in the AMPERE README document.


Anderson, B. J., R. Angappan, A. Barik, S. K. Vines, S. Stanley, P. B. Bernasconi, H. Korth, and R. J. Barnes (2021), Iridium Communications Satellite Constellation Data for Study of Earth's Magnetic Field, submitted to Geochemistry, Geophysics, Geosystems (G3), Revision date 14 April 2021, doi:10.1002/essoar.10506892.1.

Finlay, C. C., S. Maus, C. D. Beggan, et al. (2010), International Geomagnetic Reference Field: the eleventh generation, Geophys. J., 183, 1216-1230, doi: 10.1111/j.1365- 246X.2010.04804.x.

The VGO Data Products can be downloaded as a zip file ate the link below:

VGO Data Products

© Johns Hopkins Applied Physics Laboratory 2012