Wave Propagation and Shock Formation in Different Magnetic Structures

Velocity oscillations 'measured' simultaneously at the photosphere and the chromosphere-from time series of spectropolarimetric data in the 10830 A region-of different solar magnetic features allow us to study the properties of wave propagation as a function of the magnetic flux of the structure (i.e., two different-sized sunspots, a tiny pore, and a facular region). While photospheric oscillations have similar characteristics everywhere, oscillations measured at chromospheric heights show different amplitudes, frequencies, and stages of shock development depending on the observed magnetic feature. The analysis of the power and the phase spectra, together with simple theoretical modeling, lead to a series of results concerning wave propagation within the range of heights of this study. We find that, while the atmospheric cutoff frequency and the propagation properties of different oscillating modes depend on the magnetic feature, in all the cases the power that reaches the high chromosphere above the atmospheric cutoff comes directly from the photosphere by means of linear vertical wave propagation rather than from nonlinear interaction of modes.