On the extended 23rd solar cycle dynamo-period

Krivodubskij Valery, krivod1@observ.univ.kiev.ua, Astronomical Observatory, Kiev National Taras Shevchenko University

Abstract
An explanation of the mastery of the extended 23rd solar cycle duration about 13 years in the frame of the alpha-Omega dynamo model is proposed. We take into account the recently observed data on the essential increase of averaged annual module of sunspot magnetic fields Bsp [Lozitskaya et al. 2007, Izv. CrAO 107, No. 4, 59], as well as the magnetic quenching of the alpha-effect [Krivodubskij 2005, AN 326, No.1, 61] which is application-dependent with this observed fact on the increasing value of the averaged sunspot fields. The period of the solar cycle in alpha-Omega dynamo is defined by the expression, which depends on the helicity parameter alpha of the turbulent pulsations in the solar convection zone (SCZ), and the radial gradient of the inner solar rotation in the SCZ. The magnetic back reaction on the alpha-effect (self-induction) causes decreasing (quenching) of the helicity parameter that leads to increasing of cycle dynamo-period.According to the study of Lozitskaya et al. 2007 the average values of sunspot magnetic field magnitudes in the 23rd cycle are really higher (about 13%) then in three last cycles. In accordance this the value of alpha parameter was magnetically quenched about 0,7. In this case the calculated dynamo-period of the 23rd cycle must be increaser in 1,2 times. If we take into account that the average solar cycle duration is about 11 years, then the 23 cycle dynamo-period will be about 13 years. So there no is any mastery of the 23rd solar cycle period!