Non-monotonic growth and motion of the South Atlantic Anomaly

Earth, Planets and Space

Maxime Lézin¹  Hagay Amit¹  Filipe Terra-Nova²  Ricardo I. Trindade² 

[1]CNRS UMR 6112, Université de Nantes, Laboratoire de Planétologie et de Géodynamique, 2 rue de la Houssinière, 44000, Nantes, France

[2]Departamento de Geofísica, Instituto de Astronomia, Geofísica e Ciências Atmosféricas, Universidade de São Paulo, Cidade Universitária, Rua do Matão, 1226, 05508-090, São Paulo, Brazil

关键词: Geomagnetic field;    Secular variation;    South Atlantic Anomaly;    Core–mantle boundary;   

DOI  :  10.1186/s40623-021-01356-w

来源: Springer

【 摘 要 】

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 variation 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.

【 授权许可】

CC BY