Magnetohydrodynamics Simulation of the Solar Emerging Flux with
Cooling and Heating

S. Nozawa (Ibaraki Univ.) and K. Takahashi

We study the nonlinear magnetohydrodynamics (MHD) of solar magnetic
flux emerging from the convection zone into the photosphere and
chromosphere by taking into account the radiative cooling and the
static heating.  The emerging process of the magnetic flux initiated
by the magnetic buoyancy instability (i.e., convective-Parker
instability) is studied using a two or three dimensional MHD code.  We
find the following: (1) An initially weak convection zone magnetic
flux (~600G) is amplified up to ~1000 -- 1500 G by the convective
collapse of the flux tube triggered by downflow along the tube in a
very short time (< 30 min) after emerging into the photosphere.  (2)
It is apparent that convective instability evolves into a longitudinal
oscillation with a period of 400-600s.  And the convection zone of our
simulation is has the continues convective motions, therefore we think
the reconnection is occur in the convection zone.