Statistical analysis of the sunspot area and magnetic flux variations in 1996-2005 extracted from the Solar Feature Catalogue

This research presents some statistical properties of sunspots and their magnetic fields extracted in from May 1996 to May 2005 from the SOHO/MDI full disk whitelight images and magnetograms for the searchable Solar Feature Catalogue (SFC) using the automated pattern recognition techniques. A comparison of the total sunspot areas on a given day from the SFC with the daily sunspot areas available from US AF SOON data for 2000-2004 reveal a very good correlation of the datasets with the correlation coefficient of ∼93%. The total sunspot areas in the Northern and Southern hemispheres measured from a single solar image and their cumulative areas during the whole cycle are shown to have a strong North-South asymmetry with the Northern hemisphere prevailing around and after the maximum while the Southern one Schatten taking over towards the coming solar minimum. The similar N-S asymmetry is observed in a total and resulting, or excess, magnetic fluxes. The former is found to follow closely the N-S asymmetry in the sunspot areas while the latter shows a very significant flux separation in the opposite hemispheres. The excess flux is negative in the Southern hemisphere and positive in the Northern one during a long period from 1997 until 2004. During the solar minimum in 1996, the signs of total excess fluxes in the hemispheres are changed to the opposite and a similar change appears in 2003-2004 towards the approaching solar minimum. Since the magnetic field in sunspots is those of the leading polarity, so the excess magnetic flux evolution is believed to show a change of the magnetic field leading polarity during the solar cycle minima, while the asymmetry of the total magnetic flux, possibly, reflects the asymmetry of a poloidal magnetic field, as it is predicted by the oscillatory dynamo models.