Enhanced Coronal Heating and 3d Solar Magnetic Fields in AR 7321

The photospheric vector magnetic fields, Ho and soft X-ray images of AR 7321 were simultaneously observed with the Solar Flare Telescope at Mitaka and the Soft X-ray Telescope of Yohkoh on 26 October 1992, when there were no drastic activities in this region. Taking the observed photospheric vector magnetic fields as the boundary condition, the 3D magnetic fields above the photosphere were computed with a new extrapolation method. Through a comparison among 3D magnetic fields, Hα features, and soft X-ray features, the following results have been obtained: (a) Magnetic separatrices or quasi-separatrix layers play an important role in chromospheric and coronal heating, but they do not seem to be dominant in the enhanced coronal heating. (b) The enhanced coronal heating might be due, not only to the magnetic shear, but also to the emerging magnetic flux