How does the chromosphere affect the free magnetic energy loading that leads to solar eruptions?
The foot-points of the coronal magnetic field are in continuous motion by the action of the convective velocity field. Fast motion excites waves and slow motion slowly build up the free magnetic energy that is eventually released in reconnection at all scales (nano-flares, microflares, flares, coronal mass ejections).
In SAM we will use the radiation magnetohydrodynamic models to study the magnetic energy loading. We will:
perform larger scale simulations (100 Mm x 100 Mm) to study the build up of magnetic energy in small active regions;
synthesize the polarization signal in spectral lines from both the high resolution models and the larger scale simulations to study how the observations can be transformed into physical quantities;
use the simulations as a testing bed for the development of improved techniques where the photospheric extrapolation is assisted by the incorporation of chromospheric observables.
Figure 1: Comparison between observations and simulations of Alfv´enic waves. The left panel shows a snapshot from a 3D radiative MHD simulation that encompasses a region from the convection zone up to the corona. This self-consistent numerical simulation shows that the field lines (red lines) in the corona, transition region and chromosphere are continuously shaken and carry Alfv´enic waves. The coloring in this snapshot shows the temperature of the plasma with lower temperatures (chromosphere) in red, and higher temperatures (transition region) in green. A spacetime cut of the chromospheric Ca II H 3968 °A synthetic intensity (from the simulations) is shown in the upper right panel. Similar half-sinusoidal and linear tracks appear as in a spacetime plot from the observations (lower right panel). From De Pontieu, McIntosh, Carlsson et al. 2007, Science 318,1574.
