AMPERE Virtual Geomagnetic Observatory (VGO) Higher Level Data Products

AMPERE Virtual Geomagnetic Observatory (VGO) 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. VGO estimates were derived from Iridium Block-1 satellite magnetic field observations as described in Anderson et al. (2021), which should be studied before using this high-level dataset.

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. Apart from this calibration scale factor, the VGO data reflects the true geometry of the geomagnetic field.

Dates for which VGO data are provided span from January 2010 to December 2016 in a non-monotonic fashion. These dates were selected to be the quietest set of days within each month and quarter as described in Anderson et al. (2021).

VGO data file contents:

• The magnetic field difference relative to IGRF-11 at 780 km attitude for each geographic latitude and longitude entry.
• The magnetic field is given in spherical polar coordinates, radial, polar angle (theta) increasing southward (i.e., co-latitude), and azimuth (phi) increasing eastward.

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.