Influence of the Conversion Layer on the Dispersion Relation of Waves in the Solar Atmosphere

Abstract

Observations carried out with the Magneto-Optical Filter at Two Heights (MOTH) experiment show upward-traveling wave packets in magnetic regions with frequencies below the acoustic cut-off. We demonstrate that the frequency dependence of the observed travel times, i.e. the dispersion relation shows significant differences in magnetic and non-magnetic regions. More importantly, at and above the layer where the Alfven speed equals the sound speed we do not see the dispersion relation of the slow acoustic mode with a lowered cut-off frequency. Our comparisons with theoretical dispersion relations do not suggest this is the slow acoustic wave type for the upward low-frequency wave. From this we speculate that partial mode conversion from the fast acoustic to the fast magnetic wave might take place.

arXiv commentaccepted for publication in Solar Physics

References in corpus (5)

• Solar Atmospheric Oscillations and the Chromospheric Magnetic Topology
• Solving the discrepancy between the seismic and photospheric solar radius
• NLTE model calculations for the solar atmosphere with an iterative treatment of opacity distribution functions
• Physical Properties of Wave Motion in Inclined Magnetic Fields Within Sunspot Penumbrae
• First local helioseismic experiments with CO5BOLD

Cited by in corpus (1)

• The energy of waves in the photosphere and lower chromosphere: II. Intensity statistics