Abstract | The chromosphere is arguably the most difficult and least understood domain of solar physics. All at
once it represents the transition from optically thick to thin radiation escape, from gas-pressure
domination to magnetic-pressure domination, from neutral to ionised state, from MHD to plasma
physics, and from near-equilibrium ("LTE") to non-equilibrium conditions.
The heating requirements of the solar chromosphere are not easily determined since the radiative
cooling is dominated by optically thick spectral lines that form far from equilibrium. Energy estimates
are therefore very model dependent. 1D semi-empirical model atmospheres indicate that to maintain
the quiet, average solar chromosphere, the required energy input is in the range 2-12 kW/m2 but these
models neglect many important aspects like the dynamics of the chromosphere, non-equilibrium
ionization effects and spatial structuring.
In this talk we will review the modelling of the Solar Chromosphere - from 1D semi-empirical models
to 3D radiation magnetohydrodynamic models with increasing level of realism in the physical
approximations. |