Numerical and observational studies of magnetic reconnection
in the solar corona.

H. Isobe

The occurence of magnetic reconnection in the solar corona
has been established by Yohkoh and following space-based
observations such as SOHO and TRACE. Solar observers are now
tryng to address more fundamental issues on the physics of
reconnection such as reconnection rate and role of plasmoid
ejection. In the first half of the talk I will review recent
observational studies on reconnection in the solar atmosphere
which include: direct observations of reconnection inflow/outflow,
relation of multiple plasmoid ejections and hard X-ray emissions,
and qualitative studies of the energy release rate and the
reconnection rate.
In the rest of the talk I will review the MHD simulations
of reconnection-associated phenomena in the Sun, such as flares,
jets, and coronal mass ejections. Particularly I will present
the results of our three-dimensional MHD simulation of
solar emerging flux and its reconneciton with pre-existing
coronal field, which was carried out on the Earth Simulator.
We found that filametnary structure is spontaneously formed in
the emerging flux due to the magnetic Rayleigh-Taylor instability.
As a result, reconnection with pre-existing coronal field occurs
in a spatially intermittent way. We propose that such a "patchy"
reconnection can occur in various dynamically evolving phenomena
and explain the intermittent nature of reconnection.