Nonlinear MHD Rossby wave interactions and persistent geomagnetic field structures

Autor(es)

Raphaldini, Breno ^[1] ; Raupp, Carlos F. M. ^[1]

Afiliação do(s) autor(es)

^[1] Univ Sao Paulo, Inst Astron Geophys & Atmospher Sci, Sao Paulo - Brazil

• Tipo de documento: Artigo Científico
• Fonte: PROCEEDINGS OF THE ROYAL SOCIETY A-MATHEMATICAL PHYSICAL AND ENGINEERING SC; v. 476, n. 2241 SEP 30 2020.
• Citações Web of Science: 0

Resumo

The geomagnetic field presents several stationary features that are thought to be linked to inhomogeneities at the core-mantle boundary. Particularly important stationary structures of the geomagnetic field are the flux lobes, which appear in pairs in mid- to high mid- to high latitudes. A recently discovered stratified layer at the top of the Earth's core poses important constraints on the dynamics at this layer and on the interaction of the core dynamics and the base of the mantle. In this article, we introduce the linear and nonlinear theories of magnetic Rossby waves in a thin shell at the top of the Earth's core. We study the nonlinear interaction of these waves in the presence of prescribed forcings at the base of the mantle of both a thermal and a topographic nature. We show that the combined effects of forcing and nonlinear interaction can lead the wave phases to be locked around a particular geographical longitude, generating a quasi- stationary flow pattern with a significant meridional component. The solutions of the system are shown to be analogous to atmospheric blocking phenomena. Therefore, we argue that persistent and long-lived structures of the geomagnetic field, such as the geomagnetic lobes, might be associated with a blocking at the top of the Earth's core due to nonlinear stationary waves. (AU)

• Processo FAPESP: 17/23417-5 - Variabilidade paleoclimática da Zona de Convergência do Atlântico Sul e processos no Oceano Atlântico e Pacífico: Último Glacial, Holoceno Médio e Último Milênio
• Beneficiário: Breno Raphaldini Ferreira da Silva
• Modalidade de apoio: Bolsas no Brasil - Pós-Doutorado
• Processo FAPESP: 15/50686-1 - Paleo-vínculos na evolução das monções e dinâmica
• Beneficiário: Pedro Leite da Silva Dias
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