Magnetic and velocity field of sunspots in the photosphere und upper chromosphere

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This thesis presents the properties of magnetic and velocity fields of sunspots at various scales in the photospheric and upper chromospheric layers of the Sun. An analysis of the Doppler velocity maps of penumbral filaments obtained from the deeply formed photospheric C I 5380 Å spectral line observed with the Swedish Solar Telescope (SST) provides observational evidence of overturning convection as the predominant heat transport mechanism in the penumbra. A study of the vertical gradient of the sunspot magnetic field in the photospheric layer reveals the presence of patches in the inner penumbra, where the magnetic field decreases with depth. The three dimensional structure of the magnetic field of a sunspot is analyzed using the photospheric Si I 10827.1 Å spectral line and the chromospheric He I triplet at 10830 Å observed at the German Vacuum Tower Telescope (VTT).