S. J. Mumford, V. Fedun, R. Erdélyi
Aims. Recent ground- and space-based observations reveal the presence of small-scale motions between convection cells in the solar photosphere. In these regions small-scale magnetic flux tubes are generated due to the interaction of granulation motion and background magnetic field. This paper aims to study the effects of these motions, in regions of enhanced magnetic field, on magnetohydrodynamic wave excitation, propagation and energy flux from the solar photosphere up towards the solar corona. Methods. Numerical experiments of magnetohydrodynamic wave propagation in a realistic gravitationally stratified solar atmosphere from five different modelled photospheric drivers are performed. Horizontal and vertical drivers to mimic granular buffeting and solar global oscillations, a uniform torsional driver, an Archimedean spiral and a logarithmic spiral to mimic observed torsional motions in the solar photosphere are investigated. The numerical results are analysed using a novel method for extracting the parallel, perpendicular and azimuthal components of the perturbations, which can cater for linear and non-linear perturbations. Employing this method yields the identification of the wave modes excited in the numerical simulations and enables a comparison of the percentage energy flux for all of the wave modes. Results. The energy flux balance is calculated for each wave mode excited by each of the simulated drivers. The torsional drivers are found to drive primarily Alfv\'en modes (approximately 60%) with small contributions of the slow kink mode, and, for the logarithmic spiral driver, small amounts of excited slow sausage mode is found. The horizontal and vertical drivers excite primarily slow kink mode or slow and fast sausage modes respectively, with small variation dependent upon flux surface radius.
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http://arxiv.org/abs/1305.7415
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