Thinkshop12

Magnetic Field Reconstruction Based on Chromospheric Sunspot Oscillations

Johannes Löhner-Böttcher (Kiepenheuer-Institut für Sonnenphysik Freiburg)

Abstract. The highly dynamic solar atmosphere exhibits a wealth of MHD modes. The strong magnetic fields of sunspots guide these waves from the lower to the upper atmosphere. The most dominant phenomena are the bright umbral flashes and running penumbral waves. As found by Bel & Leroy (1977) and De Pontieu et al. (2004), the cut-off frequency for the propagating waves depends on the ambient sound speed and the inclination angle of the magnetic field lines. From an observational point of view (see Löhner-Böttcher & Bello González 2015), we investigate the dominant frequencies present in sunspots. A 1h-time series of multi-wavelength observations of NOAA11823 taken at high spatial and temporal resolution with ROSA and IBIS at the DST is analyzed. The spatial distribution of peak frequencies for a fine sample of photospheric to chromospheric layers is revealed. Going one step further, we present the successful height-sampled reconstruction of the magnetic field inclination for a sunspot. The results agree to the inclinations obtained by HMI inversion and potential magnetic field extrapolations (PFSS).

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