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Radial vorticity constraint in the core flow modeling

EGU2011-2631. Radial vorticity constraint in the core flow modeling. Section 2.3 Earth’s Magnetic Field GFZ Potsdam, Germany. Seiki Asari & Vincent Lesur. Strong field?. A scenario of “fast torsional waves”. Gillet et al. 2010. Intensity of several mT?.

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Radial vorticity constraint in the core flow modeling

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  1. EGU2011-2631 Radial vorticity constraint in the core flow modeling Section 2.3 Earth’s Magnetic Field GFZ Potsdam, Germany Seiki Asari & Vincent Lesur EGU 2011 General Assembly, Vienna, Austria

  2. Strong field? A scenario of “fast torsional waves” Gillet et al. 2010 Intensity of several mT? EGU 2011 General Assembly, Vienna, Austria

  3. Radial vorticity equation near the CMB Leading order: Magnetostrophic balance Tangential geostrophy (TG) EGU 2011 General Assembly, Vienna, Austria

  4. Approximation Approximation: Electrically Insulating mantle Mantle conductance: EGU 2011 General Assembly, Vienna, Austria

  5. Radial vorticity constraint Rarial vorticity constraint (RVC) Nec. cond.: Historic obs. Suf. cond.: Satellite obs. EGU 2011 General Assembly, Vienna, Austria

  6. Sorting core flow RVC TG flow class 1 RVC compatible flow class 2 RVC incompatible flow Ageostrophic flow class 3 EGU 2011 General Assembly, Vienna, Austria

  7. 2 3 Damping matrices Tangential geostrophy constraint class 2 + 3 Radial vorticity constraint • 2 3 class 3 EGU 2011 General Assembly, Vienna, Austria

  8. Modeling settings • Magnetic model: GRIMM-2 • Period: 2000.0 - 2010.0 • Flow inversion: Spectral method • SH truncation: MF & SV 14 Flow 27 • Spline order: 6 EGU 2011 General Assembly, Vienna, Austria

  9. 0c 1c 1c 0c 1c 1c 0c 0c 1 1 1 1 1 1 2 2 Flow degree of freedom Toroidal flow Poloidal flow RVC TG … … t , t , t , t , s , s , s , s , EGU 2011 General Assembly, Vienna, Austria

  10. Maps at 2005.0 TG RVC Nothing EGU 2011 General Assembly, Vienna, Austria

  11. LOD predictions Obs. RVC TG EGU 2011 General Assembly, Vienna, Austria

  12. Short-period torsional waves TG RVC Equator Pole EGU 2011 General Assembly, Vienna, Austria

  13. Electric current density Thermodynamic upper limit • compatible with • “fast torsional waves” • greater than the previous • estimate in favor of TG and decadal torsional oscillations EGU 2011 General Assembly, Vienna, Austria

  14. Additional constraints • Pure toroidal flow constraint • Helical flow constraint EGU 2011 General Assembly, Vienna, Austria

  15. Solutions RVC + Pure toroidal flow RVC + Helical flow SV (though barely) SV EGU 2011 General Assembly, Vienna, Austria

  16. Conclusioins • Radial vorticity constraint implemented in the core flow modeling • When compared with pure TG flow • Better fit to GRIMM-2 SV • Poloidal flow components having notably larger degree of freedom • LOD prediction correlated as well with the subdecadal LOD observation • Decadal torsional oscillations contradicted • Pure toroidal flow not compatible at the same time EGU 2011 General Assembly, Vienna, Austria

  17. EGU 2011 General Assembly, Vienna, Austria

  18. Trade-off Tangential geostrophy constraint Radial vorticity constraint 1+2+3 1+2+3 1 1 2+3 2+3 2 2 3 3 1TG flow 2+3Ageostrophic flow EGU 2011 General Assembly, Vienna, Austria

  19. Spectral domain analysis Radial vorticity constraint Spherical harmonic expansion Toroidal & poloidal coefficients of Poloidal coefficients of EGU 2011 General Assembly, Vienna, Austria

  20. Misfit TG RVC Misfit (Moderate-fit) GRIMM-2 SV Misfit (Tight-fit) Free decay Non-modeled SV EGU 2011 General Assembly, Vienna, Austria

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