The magnetic connection between the solar photosphere and the corona

The solar magnetic field that extends through the chromosphere into the corona is envisioned to fan out from strong flux concentrations located within the supergranular downflow lanes. That so-called network field appears to be surrounded by a mixed-polarity magnetic field with a scale comparable to that of the granulation. We argue that for an internetwork field with a magnitude of a few tens of Mx cm(-2), as suggested by both observations and models, the commonly held notion of a wineglass-shaped magnetic canopy of network flux that fully encloses weakly magnetic regions below it is fundamentally wrong. We estimate that in the presence of such a relatively strong internetwork field, as much as half of the coronal field over very quiet Sun may be rooted in that mixed-polarity internetwork field throughout the supergranules rather than in the network flux concentrations, as assumed until now. A corresponding amount of flux forms collars of closed loops around the network concentrations, connecting network flux back down onto the internetwork field over distances of several thousand kilometers. Within such a geometry, the rapid evolution of the internetwork field may substantially affect coronal heating and the acceleration of the solar wind. We discuss the potential consequences of these interacting network and internetwork fields for atmospheric heating, for wave propagation and the formation of acoustic shadows, and for the appearance of the near-surface solar outer atmosphere.