| dc.description.abstract | In this thesis the role of magnetohydrodynamic (MHD) waves in the heating of the solar corona is investigated, not only as a direct source of heating but as also a triggering mechanism for flares and as a progenitor of other heating mechanisms such as MHD shocks. These investigations are carried out primarily using MHD simulations and in particular using the MHD numerical code, Lare3d, which solves the full set of compressible resistive MHD equations in three dimensions. To begin this thesis a potential magnetic field calculator is presented that can be used to produce stable coronal magnetic field extrapolations from photospheric magnetic field measurements. In the following chapter it is shown through simulations that oscillations of emerging bipolar regions in the photosphere can dramatically increase the strength of triggered flares by causing more disruption to the overlying field. Moving on from this it is found, through further simulations, that shear Alfv´enic oscillations at the photosphere can generate torsional Alfvén waves higher in the atmosphere through the mechanism of mode coupling. It is then shown through the comparison of analytic predictions and numerical simulations that the dissipation of torsional Alfvén waves through phase mixing can be accurately predicted analytically within the limits of the WKB approximation and that damping is stronger than predicted by the analytic formula beyond the limits of the WKB approximation. Finally it is demonstrated through MHD simulations that in addition to the dissipative effects of phase mixing, torsional Alfvén waves undergo nonlinear mode coupling to magnetosonic modes that can heat the solar corona through different mechanisms such as shock heating. | en_US |
