1. EGU GENERAL ASSEMBLY
Oesterreich, Wien, April 2012
Theory, Simulations and Observations of Magnetic Dynamos
Long-term dynamics of solar cycle, geomagnetic reversals and fluctuations of dynamo governing parameters
Dmitry Sokoloff
Moscow, Russia
In collaboration with
D.Moss, I.Usoskin,
V.Pipin, G.Sobko,
V.Tutubalin

2. Magnetostrophic timescale

3. Gassendi
La Hire
Dalton

4. BP BT BT BP Parker Dynamo Ω Differential rotation α Mirror asymmetry
Fluctuations of governing
parameters.
Alpha is weak and
fluctuations are stronger
(up to 20%)
Novelty: long-term fluctuations
Suggested by Hoyng in 90th

5. α-effect
τ < v rot v >
α = 3
E = αB

6. Normal cycle

7. Beginning of the Maunder minimum
Gassendi
Scheiner
Picard
Hevelius
No spots
Asymmetric cycle

8. Asymmetric dynamo wave
End of the Maunder Minimum
Picard
La Hire
No dynamo wave
Asymmetric dynamo wave
Normal cycle

9. Solar Cycle in XVIII cent.

10. Grand Minima

13. Geodynamo

14. Basic Regimes of Parker Dynamo

15. Field Reversals

16. Simulated and observed timescales