Non-monotonic growth and motion of the South Atlantic Anomaly

Author(s)

Amit, Hagay ^[1] ; Terra-Nova, Filipe ^[2] ; Lezin, Maxime ^[1] ; Trindade, Ricardo I. ^[2]

Affiliation

^[1] Univ Nantes, CNRS, Lab Planetol & Geodynam, UMR 6112, 2 Rue Houssiniere, F-44000 Nantes - France

^[2] Univ Sao Paulo, Dept Geofis, Inst Astron Geofis & Ciencias Atmosfer, Cidade Univ, Rua Matao 1226, BR-05508090 Sao Paulo - Brazil

• Document type: Journal article
• Source: EARTH PLANETS AND SPACE; v. 73, n. 1 DEC 8 2021.
• Web of Science Citations: 0

Abstract

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. (AU)

• FAPESP's process: 18/07410-3 - Persistence of the South Atlantic Anomaly in geomagnetic observations, field models and numerical dynamos
• Grantee: Filipe Terra Nova dos Santos
• Support Opportunities: Scholarships in Brazil - Post-Doctoral