The Morphologic Properties of Magnetic Networks over the Solar Cycle 23

Abstract

The morphologic properties of the magnetic networks during Carrington Rotations (CRs) 1955-2091 (from 1999 to 2010) have been analyzed by applying the watershed algorithm to magnetograms observed by the Michelson Doppler Interferometer on board the Solar and Heliospheric Observatory spacecraft. We find that the average area of magnetic cells on the solar surface at lower latitudes (within ±50°) is smaller than that at higher latitudes (beyond ±50°). Statistical analysis of these data indicates that the magnetic networks are fractal in nature and the average fractal dimension is D_f = 1.253 ± 0.011. We also find that both the fractal dimension and the size of the magnetic networks are anti-correlated with the sunspot area. This is perhaps because a strong magnetic field can suppress spatially modulated oscillation and compress the boundaries of network cells, leading to smoother cell boundaries. The fractal dimension of the cell deviates from that predicted from an isobar of Kolmogorov k ^-5/3 homogeneous turbulence.