1. 1

2. 2 Apologies from Ed and Karl-Heinz

3. 3

4. 4

5. 5

6. 6

7. 7

8. 8 SoFin@NOT

9. 9 Near-surface shear layer: spots rooted at r/R=0.95? Benevolenskaya, Hoeksema, Kosovichev, Scherrer (1999) Pulkkinen & Tuominen (1998)  =  AZ  =(180/  ) (1.5x10 7 ) (2  10 -8 ) =360 x 0.15 = 54 degrees!

10. 10 Forced large scale dynamo with fluxes geometry here relevant to the sun Negative current helicity: net production in northern hemisphere 10 46 Mx 2 /cycle

11. 11 Solar dynamos in the 1970s Distributed dynamo (Roberts & Stix 1972) –Positive alpha, negative shear Yoshimura (1975)

12. 12 Distributed dynamos  max at 60 Mm depth  t = 3x10 12 cm 2 /s depth  [cgs] U rms B eq  [d]  t [cgs] 240.0047016001.31.5 390.015620002.82 1500.12253000223 2000.246001600.6 Krivodubskii (1984) 

13. 13 In the days before helioseismology Angular velocity (at 4 o latitude): –very young spots: 473 nHz –oldest spots: 462 nHz –Surface plasma: 452 nHz Conclusion back then: –Sun spins faster in deaper convection zone –Solar dynamo works with d  /dr<0: equatorward migr

14. Before helioseismology Angular velocity (at 4 o latitude): –very young spots: 473 nHz –oldest spots: 462 nHz –Surface plasma: 452 nHz Conclusion back then: –Sun spins faster in deaper convection zone –Solar dynamo works with d  /dr<0: equatorward migr Yoshimura (1975) Thompson et al. (2003) Brandenburg et al. (1992)

15. 15 Application to the sun: spots rooted at r/R=0.95 Benevolenskaya, Hoeksema, Kosovichev, Scherrer (1999) –Overshoot dynamo cannot catch up  =  AZ  =(180/  ) (1.5x10 7 ) (2  10 -8 ) =360 x 0.15 = 54 degrees!

16. 16 Arguments against and in favor? Flux storage Distortions weak Problems solved with meridional circulation Size of active regions Neg surface shear: equatorward migr. Max radial shear in low latitudes Youngest sunspots: 473 nHz Correct phase relation Strong pumping (Thomas et al.) 100 kG hard to explain Tube integrity Single circulation cell Turbulent Prandtl number Max shear at poles* Phase relation* 1.3 yr instead of 11 yr at bot Rapid buoyant loss* Strong distortions* (Hale’s polarity) Long term stability of active regions* No anisotropy of supergranulation in favor against Tachocline dynamosDistributed/near-surface dynamo Brandenburg (2005, ApJ 625, 539)

17. 17 Origin of sunspot Theories for shallow spots: (i) Collapse by suppression of turbulent heat flux (ii) Negative pressure effects from - vs B i B j

18. 18 clockwise tilt (right handed)  left handed internal twist Build-up & release of magnetic twist New hirings: 4 PhD students4 PhD students 4 post-docs (2yr)4 post-docs (2yr) 1 assistant professor1 assistant professor 2 Long-term visitors2 Long-term visitors Upcoming work: Global modelsGlobal models Helicity transportHelicity transport coronal mass ejectionscoronal mass ejections Cycle forecastsCycle forecasts Coronal mass ejections

19. 19 Cycle dependence of  (r,  )

20. 20 Sunspots

21. 21 How deep are sunspots rooted? Solar activity may not be so deeply rooted The dynamo may be a distributed one Near-surface shear important Hindman et al. (2009, ApJ)

22. 22 Near-surface shear layer Benevolenskaya, Hoeksema, Kosovichev, Scherrer (1999)

23. 23 Flux emergence: observations & simulations Hindman et al. (2009, ApJ) Brandenburg (2005, ApJ)

24. 24 Flux emergence: simulations and models Active regions from an instability Suppression of turbulent motions Cooling, contraction, field amplification in preparation with Kleeorin & Rogachevskii

25. 25 Winter School 11-22 January

26. 26 http://spaceweather.com