ИЗМЕНЕНИЯ МАГНИТНОЙ СПИРАЛЬНОСТИ В СОЛНЕЧНОМ ЦИКЛЕ Kirill Kuzanyan ИЗМИРАН, Россия Zhang H., Gao Yu Национальные Астрономические Обсерватории АН КНР

Question: Can we learn more of solar activity looking at magnetic helicity?

Physics of the solar cycle Solar dynamo theory Regeneration of magnetic fields due to rotation and turbulent convection periodic in time travelling wave Parker 1955 dynamo wave Babcock & Leighton Krause & Rädler 1980 mean-field model

The Butterfly Diagram proxies of magnetic field (A,B)

Dynamo model with evolution of Helicity Magnetic field generation (Parker Dynamo) Parameterized equation Generation of Helicity

20 years systematic monitoring of the solar vector magnetic fields in active regions taken at Huairou Solar observing station, China ( ) More observations from Mitaka (Japan) and also Mees, MSFC (USA) etc., but only Huairou data systematically cover 20 years period.

So, theory requires the mirror asymmetry to be the same from cycle to cycle! How to measure it ?

observations Observable !

Photospheric vector magnetogram of AR (SOT at Hinode); 2006 Dec at 23:10:06-00:13:17UT.

AR 10930: H C over the filtergram; positive/negative: a typical AR. The filtergram of AR 10930; contours of current helicity H C for positive (negative) values shown in red (green), corresponding to absolute values of 0.2, 0.5, 1.0, 4.0 G 2 /m, respectively. The field of view is 104''  80''.

Observations and Data Reduction 983 active regions; 6630 vector magnetograms observed at Huairou Solar Observing Station; Time ranges from 1988 to 2005; Time average: 2 year data bins; Latitudinal: Northern hemisphere and Southern hemisphere (7 degree bins);

Helicity overlaid with butterfly diagram

Force free factor overlaid with butterfly diagram

Compare: Qualitatively, the both quantities are distributed in a similar manner. So, despite the noisy nature of the data, accuracy of measurements is reliable.

MAIN RESULTS: 1. Current helicity and twist follow the propagation of the magnetic activity dynamo waves recorded by sunspots. The mirror asymmetry plays an important role in the solar dynamo. 2. Current helicity and twist oscillate with 11-year period likewise sunspots rather than 22-year period as magnetic fields do. It can be understood as the both quantities are quadratic in magnetic field. 3. Current helicity and twist patterns are in general anti-symmetric with respect to the solar equator. This agrees with previous findings obtained in studies of 11-year observational data sets (Pevtsov & Canfield, 1994; Hagino & Sakurai, 2004).

THE MAIN RESULT Current helicity and twist follow the propagation of the magnetic activity dynamo waves recorded by sunspots. The mirror asymmetry plays an important role in the solar dynamo mechanism.

Observable properties of helicity Anti-symmetric over the solar equator Cyclic variation 11 years (not 22 years!) Time lag with respect to sunspots is about 2 years ahead, not behind! (confront with dynamo theory) Systematic sign inversion of helicity (a) at the beginning of the cycle (b) at the end of the cycle

Dynamo models help…? in prediction of the solar cycle!? The model which we considered in 1990s was far too simple! Recall the results

Nonliear Parker’s Dynamo in inhomogeneous media

поле в единицах энергии равнораспределения

Зависимость амплитуды цикла от длительности фазы роста (Dmitrieva, Kuzanyan, Obridko, 2000)

Предсказание амплитуды цикла по динамике его ветви роста прогноз цикл 23: 121

Simple self-consistent dynamo model with evolution of helicity (dynamical nonlinear dynamo) Kleeorin, Kuzanyan, Moss, Sokoloff, Rogazhevsky, Zhang, A&A, 2003; and a series of publications of the authors thereafter in

Choice of Parameter Range (Example) LATITUDE HELICITY C=0.01- ok! C=0.1 too high value

FURTHER PLAN Include meridional circulation in order to see its effect on (a)latitudinal extent of helicity versus sunspots and (b)the time lag between helicity and sunspots

Kleeorin et al EVOLUTION OF HELICITY WITH TIME ( Northern Hemisphere N ) Diffusion Time Units S N Sunspot Group Number Magnetic Energy HELICITY ~1988~1997

Summary Helicity helps in development of self- consistent dynamo models!

Thank you!