Magnetic flux evolution inside and outside a polar coronal hole based on data from the Solar Dynamics Observatory (SDO)

Abstract

This paper presents the analysis results of the magnetic flux inside and outside a polar coronal hole in the north during the period August 1–2, 2010. The location of the polar coronal hole is determined from Extreme Ultraviolet (EUV) images in the Fe XII, XXIV (193 A) line, obtained by an Atmospheric Imager Assembly (AIA) of the Solar Dynamics Observatory (SDO). Magnetic data are represented by the line-of-sight component of the magnetic field strength, measured with an Helioseismic and Magnetic Imager (HMI). Both data sets are sampled at an interval of 720 s and are remapped onto a Carrington coordinate grid with a resolution of 0.001 in sine latitude and 0.1 degree in longitude. The preliminary results show a magnetic flux of the new cycle’s polarity (positive polarity in the north) appearing inside the coronal hole on a time scale of several hours. This “new flux” does not correlate with the magnetic flux of the old solar cycle (negative polarity in the north).