Self-Organized Structures in the Solar Atmosphere: Theory and Observations.

The coupling processes between the solar surface and overlying layers of atmosphere both in the quiet Sun and active regions are reviewed. Emphasis is made on the response of the corona to magnetic activity in the underlying plage regions. We discuss observations of high resolution MDI magnetograms co-aligned with multiwavelength images taken by TRACE in chromospheric and coronal lines. We show that EUV emission above plage regions dominated by single polarity magnetic elements always has an amorphous shape that topologically mimics the shape of underlying plage. Space-time slices of the amorphous emission in the coronal lines show coherent braid-like structures with almost constant periods for a given area. On the other hand, the coronal emission above mixed polarity plages is highly discrete and consists of sporadic localized microflares. Obviously, the physical processes behind the observed regularities are simply the coronal heating processes. The fact that the corona is strongly inhomogeneous in space and evolves in time in very different ways implies that the processes of energy production, flow and release have several branches. We argue that the primary energy source lies in continuous hydro-magnetic activity among the photospheric magnetic fields. The character of this activity determines the processes of the extraction of energy stored in the photospheric magnetic fields, as well as energy transport throughout the solar atmosphere.