Comparison of magnetic flux distribution between a coronal hole and a quiet region

Employing Big Bear Solar Observatory (BBSO) deep magnetograms and Ha images in a quiet region and a coronal hole, observed on 2004 September 14 and 16, respectively, we have explored the magnetic flux emergence, disappearance, and distribution in the two regions. We obtain the following results. (1) The evolution of magnetic flux in the quiet region is much faster than that in the coronal hole, as the flux appearing in the form of ephemeral regions in the quiet region is 4.3 times as large as that in the coronal hole, and the flux disappearing in the form of flux cancellation is 2.9 times as fast as in the coronal hole. (2) More magnetic elements with opposite polarities in the quiet region are connected by arch filaments, estimating from magnetograms and Ha images. (3) We measured the magnetic flux of about 1000 magnetic elements in each observing region. The flux distribution of network and intra-network (IN) elements is similar in both polarities in the quiet region. For network fields in the coronal hole, there are many more negative elements than positive elements. However, for the IN fields, there are many more positive elements than negative elements. (4) In the coronal hole, the fraction of negative flux obviously changes with a different threshold flux density; 73% of the magnetic fluxes with a flux density larger than 2 G have negative polarity, and 95% of the magnetic fluxes are negative, if we only consider the fields with a flux density larger than 20 G. Our results demonstrate that in a coronal hole, stronger fields are occupied by one predominant polarity, but the majority of weaker fields are occupied by the opposite polarity.