In the framework of studying the internal dynamics of the Earth\u2019s outer core using numerical models, we use reduced models under the Quasi-Geostrophic (QG) and Boussinesq hypothesis to solve for the magneto-hydro-dynamics equations (MHD) and improve our knowledge of decadal to centennial core\u2019s processes that could play a role in the so-called Atlantic Gyre or the South Atlantic Gyre.
\nWe thus present numerical hydrodynamic models and dynamos using a hybrid QG-3D approach in a thick spherical shell geometry. Our model is based on a Quasi-Geostrophic convection code extended with a 3D treatment of heat transport and magnetic induction.
\nWe find series of convective models that compare reasonably well with simulations using pure 3D codes, with convective flows that are dominated by zonal jets at mid-depths in the shell and
\nthermal Rossby waves that are prominent close to the outer boundary. Models that include laterally varying heat flux at the outer boundary are also tested and reproduce regional convection patterns that compare well with those found in similarly forced 3-D models.
\nWe also obtain a collection of self-sustained, multipolar, weak field dynamos with magnetic energy one or two orders of magnitude lower than the kinetic energy. The poloidal magnetic energy is weak and, by construction, there is a lack of equatorially anti-symmetric components in the Buoyancy and Lorentz forces. This leads to configurations where the velocity field is only weakly impacted by the magnetic field, similar to dynamos found in 3D simulations where zonal flows and the Omega-effect dominate. The time- dependence of these dynamos is characterised by quasi-periodic oscillations that we attribute to dynamo waves. The QG-3D dynamos found so far are not Earth-like.
\nOur models could also be applied to other planetary bodies sharing nearby regions of the parameters\u2019 space.<\/p>\n","protected":false},"excerpt":{"rendered":"
In the framework of studying the internal dynamics of the Earth\u2019s outer core using numerical models, we use reduced models under the Quasi-Geostrophic (QG) and Boussinesq hypothesis to solve for […]<\/p>\n","protected":false},"author":4,"featured_media":0,"template":"","meta":{"_acf_changed":false,"_price":"","_stock":"","_tribe_ticket_header":"","_tribe_default_ticket_provider":"","_tribe_ticket_capacity":"0","_ticket_start_date":"","_ticket_end_date":"","_tribe_ticket_show_description":"","_tribe_ticket_show_not_going":false,"_tribe_ticket_use_global_stock":"","_tribe_ticket_global_stock_level":"","_global_stock_mode":"","_global_stock_cap":"","_tribe_rsvp_for_event":"","_tribe_ticket_going_count":"","_tribe_ticket_not_going_count":"","_tribe_tickets_list":"[]","_tribe_ticket_has_attendee_info_fields":false,"_tribe_events_status":"","_tribe_events_status_reason":"","_tribe_events_is_hybrid":"","_tribe_events_is_virtual":"","_tribe_events_virtual_video_source":"","_tribe_events_virtual_embed_video":"","_tribe_events_virtual_linked_button_text":"","_tribe_events_virtual_linked_button":"","_tribe_events_virtual_show_embed_at":"","_tribe_events_virtual_show_embed_to":[],"_tribe_events_virtual_show_on_event":"","_tribe_events_virtual_show_on_views":"","_tribe_events_virtual_url":"","footnotes":"","_tec_slr_enabled":"","_tec_slr_layout":""},"tags":[],"tribe_events_cat":[25,22],"coauthors":[100],"class_list":["post-24484","tribe_events","type-tribe_events","status-publish","hentry","tribe_events_cat-amphitheatre","tribe_events_cat-seminaires","cat_amphitheatre","cat_seminaires"],"acf":[],"ticketed":false,"_links":{"self":[{"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tribe_events\/24484","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tribe_events"}],"about":[{"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/types\/tribe_events"}],"author":[{"embeddable":true,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/users\/4"}],"version-history":[{"count":4,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tribe_events\/24484\/revisions"}],"predecessor-version":[{"id":25077,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tribe_events\/24484\/revisions\/25077"}],"wp:attachment":[{"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/media?parent=24484"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tags?post=24484"},{"taxonomy":"tribe_events_cat","embeddable":true,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/tribe_events_cat?post=24484"},{"taxonomy":"author","embeddable":true,"href":"https:\/\/lpg-umr6112.fr\/en\/wp-json\/wp\/v2\/coauthors?post=24484"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}