Astronomical School’s Report, 2016, Volume 12, Issue 2, Pages 153–165
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UDC 523.98

The role of the alpha effect of Babcock–Leighton in the generation of poloidal magnetic field of the Sun

Krivodubskij V.N.

Astronomical Observatory, Kyiv Shevchenko National University, Ukraine


The paper reviews recent studies of cyclicity of magnetic activity of the Sun based on the αΩ-dynamo model. It is noted that there is a functional dependence between the observed values of the poloidal BP and toroidal BT magnetic fields. This allows predicting the amplitude and the strength of cycle for the measured field BP at the beginning of the cycle. Nevertheless, for a long time no positive correlations between the characteristics of sunspots cycle (Wolf number or the total area of spots) and polar magnetic flux at the end of the cycle were found. As it turned out later, this was due to the fact that the α-effect of Babcock–Leighton, defined by tilt angles of the bipolar magnetic fields, turbulent diffusion and meridional circulation, leading to regeneration of the poloidal field, is characterized by random fluctuations in time and space. The situation changed drastically after the parameter of magnetic strength of cycle was introduced, which is a product of the area of spots cycle and tilt angles of the bipolar magnetic groups. Within the framework of the αΩ-dynamo this indicates that the surface α effect of Babcock–Leighton leads to the generation of the poloidal magnetic field at the end of the current cycle, and its assimilated parameter is an integral component of future forecasts based on the solar dynamo models. Relying on the data which cover the time span of more than a century, recent studies have established that the memory interval of cycle is limited only by one cycle.

Keywords: solar activity; magnetic fields; turbulence; sunspots; activity cycles; dynamo model; predictions of solar activity; memory span of cycle


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