Physical parameters of the non-dipole components of the geomagnetic field

• Grant number: 12/24658-2
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: March 01, 2013
• End date: December 31, 2013
• Field of knowledge: Physical Sciences and Mathematics - Geosciences - Geophysics
• Principal Investigator: Gelvam André Hartmann
• Grantee: Filipe Terra Nova dos Santos
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated scholarship(s): 13/14629-8 - Spatio-temporal variations of archeomagnetic flux patches, BE.EP.IC

Abstract

The geomagnetic field that has origin in the Earth's outer core is characterized for variations of the dipole field and non-dipole fields. Non-dipole field variations for the past few centuries and millennia seem to be responsible for the decreasing of the dipole field moment and for the evolution of the large features of the geomagnetic field, like the South Atlantic Magnetic Anomaly. The physical mechanism of the outer core responsible to generate dipole field variations is possibly attributed to tangent cylinders to the inner core. However, the dipole field variations at the surface could be associated to another physical mechanism, which is less know and which first requires a detailed analysis of the time and spatial behavior at the surface and at the core-mantle boundary. This work has two main objectives: (a) Set physical parameters of the non-dipole field at the Earth's surface, and the radial field at the core-mantle boundary; (b) Establish a physical link between both two parameters through spectral analysis. In both cases, we will use the geomagnetic field models for the past 3.000 years, recently developed by Korte et al. (2011). The relationship between both parameters can suggest a physical mechanism responsible for the non-dipole field generation and evolution, which is considered a key tool for the description of the large features of the geomagnetic field in the Holocene.(AU)