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From magnetic field to sunspot number (1)

Dynamo tutorial Part 3 : From dynamo to interplanetary magnetic field Surface vs deep-seated dynamo magnetic fields Parity modulations and mode transition Coupling dynamo and surface flux evolution models. From magnetic field to sunspot number (1).

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From magnetic field to sunspot number (1)

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  1. Dynamo tutorialPart 3 : From dynamo to interplanetary magnetic fieldSurface vs deep-seated dynamo magnetic fields Parity modulations and mode transitionCoupling dynamo and surface flux evolution models Saas Fee Advanced School 2009

  2. From magnetic field to sunspot number (1) Dynamo-generated large-scale, diffuse magnetic Toroidal flux rope in the tachocline Destabilisation, buoyant rise, and emergence Concentration of emerging flux into groups of sunspots Calculate sunspot number: SSN=k (10 g + f ) Saas Fee Advanced School 2009

  3. From dynamo to interplanetary magnetic field Dynamo-generated diffuse large-scale magnetic field Active region emergence and decay Time-evolving surface distribution of large-scale magnetic field Time-evolving reconstruction of coronal magnetic field Time-evolving interplanetary magnetic field Saas Fee Advanced School 2009

  4. Surface vs deep-seateddynamo magntic fields Saas Fee Advanced School 2009

  5. Two solar dynamo models Advection-dominated alpha-Omega model with meridional circulation, base positive alpha ~ cos(theta) Babcock-Leighton model with meridional circulation and non-local surface source term Saas Fee Advanced School 2009

  6. Surface polar vs internal field (2) Saas Fee Advanced School 2009

  7. Surface polar vs internal field (3) Saas Fee Advanced School 2009

  8. Surface polar vs internal field (4) Model 2: advection-dominated alpha-Omega Saas Fee Advanced School 2009

  9. Surface polar vs internal field (5) Model 1: classical alpha-Omega with equatorial alpha Saas Fee Advanced School 2009

  10. Global 3D MHD simulations Polar cap flux Tachocline B2 Saas Fee Advanced School 2009

  11. Parity modulationsand mode transitions Saas Fee Advanced School 2009

  12. Amplitude and parity modulations Figure courtesy S. Tobias Saas Fee Advanced School 2009

  13. Global 3D MHD simulations Saas Fee Advanced School 2009

  14. Mode transition, global 3D MHD Tesla (1200 solar days = 100 yr) Saas Fee Advanced School 2009

  15. Coupling dynamoand surface flux evolution models Saas Fee Advanced School 2009

  16. Global 3D MHD simulations Saas Fee Advanced School 2009

  17. Backup material Saas Fee Advanced School 2009

  18. The polar field as a precursor (1) PDF: Schatten et al 1978 Saas Fee Advanced School 2009

  19. An (the?) explanation Schematically, in flux transport models the cycle runs as follows: With stochasticity in the poloidal source term, this becomes: Forecasting does not work across a « stoch » arrow !!: In models with spatially coincident poloidal and toroidal source mechanisms, the cycle runs as: Precise forecasting is now impossible! Saas Fee Advanced School 2009

  20. The minimum to remember from this lecture We do not know how to relate quantitatively the sunspot number to the strength of the dynamo-generated large-scale B Stochastic forcing is (likely) an important driver of cycle fluctuations Intermittency arises naturally in dynamo models with a lower operating threshold, but a distinct (dynamo?) mechanism is needed to kickstart the primary dynamo again Be very, very suspicious of any solar cycle forecast Saas Fee Advanced School 2009

  21. The SSN as a precursor ? Model 3: Babcock-Leighton with non-local surface source Saas Fee Advanced School 2009

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