EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Non-monotonic growth and motion of the South Atlantic Anomaly

Hagay Amit1, Filipe Terra-Nova2, Maxime Lézin1, and Ricardo Trindade2
Hagay Amit et al.
  • 1Universite de Nantes, CNRS UMR 6112, Nantes, France (
  • 2Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, São Paulo, Brazil (

The South Atlantic Anomaly (SAA) is a region at Earth’s surface where the intensity of the magnetic field is particularly low. Accurate characterization of the SAA is important for both fundamental understanding of core dynamics and the geodynamo as well as societal issues such as the erosion of instruments at surface observatories and onboard spacecrafts. Here, we propose new measures to better characterize the SAA area and center, accounting for surface intensity changes outside the SAA region and shape anisotropy. Applying our characterization to a geomagnetic field model covering the historical era, we find that the SAA area and center are more time dependent, including episodes of steady area, eastward drift and rapid southward drift. We interpret these special events in terms of the secular vari‑ation of relevant large‑scale geomagnetic flux patches on the core–mantle boundary. Our characterization may be used as a constraint on Earth‑like numerical dynamo models.

How to cite: Amit, H., Terra-Nova, F., Lézin, M., and Trindade, R.: Non-monotonic growth and motion of the South Atlantic Anomaly, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-4635,, 2022.