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Exploring Dynamo Simulations and Dynamo Resonances in Earth's Geomagnetic Field

Discover the fascinating world of dynamo simulations, resonances, and turbulence effects on Earth's magnetic field. From Malkus-Proctor to Galloway-Proctor, delve into the complexities of planetary magnetism dynamics in a spherical simulation using the Pencil Code. Learn about key concepts such as helicity, compressibility, and thermal effects, and how they influence the geomagnetic field's behavior. Uncover the mysteries of the ABC flow dynamo and its scaling with insightful references to past studies. Delve into the nonlinear test-field method and the impacts of Lorentz force on hydromagnetically forced Roberts flow. Explore the intriguing dynamics of magnetic diffusivity, turbulence, and kinematic effects across different scales. Don't miss out on the latest research findings and future directions in geomagnetic field studies. Happy Birthday, Mike, and stay tuned for more exciting discoveries in planetary magnetohydrodynamics!

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Exploring Dynamo Simulations and Dynamo Resonances in Earth's Geomagnetic Field

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  1. Malkus-Proctor  Galloway-Proctor & happy Birthday, Mike!

  2. Stable parities1

  3. Stable parities2

  4. From Malkus-Proctor to … Elsasser number Close to 1

  5. Compressibility

  6. Thermal effects

  7. Spherical simulation w/ Pencil Code Equatorward migration Just like 30 years ago (Gilman/Glatzmaier)

  8. … to Galloway … and his ABC flow dynamo simulations … here just AB

  9. …or rather Moffatt/Proctor ’85 • No fast dynamo with finite <A.B> • ABC flow dynamo: + and – at different scale • Rm-1/2 scaling of <A.B>/<B2> with Dobler & Subramanian (2002, AN)

  10. … to Galloway-Proctor • Helical • Pseudo scalar • Circularly polarized • Axial vector •  proper vector • g effect • Only at 6th order with Rädler (2009, MNRAS)

  11. weird resonances … but clear asymptotics outside resonance range

  12. Strongly negative magn diffusivity! But dynamo still only because of a effect Rm=30

  13. What about turbulence? a and htkinematic: independent of Rm (2…200) Sur et al. (2008, MNRAS)

  14. Nonlinear test-field method essence Hydromagnetically forced Roberts flow

  15.  effects from Lorentz force Rheinhardt & B (A&A 2010) Hydromagnetically forced Roberts flow

  16. QKTFM: Rm dependence for B~Beq • l is small  consistency • a1 and a2 tend to cancel • making a small • h2 small …with Rädler, Rheinhardt, Subramanian (ApJ Lett 2008)

  17. CU next year: click from my home page

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