Median of the inferred LOS magnetic field. Top panel: variation in the LOS magnetic field with the position along the slit at log τ = −1.5 (black line, derived from inversions of the Si I 10 827 Å line) and at the chromosphere (red line, derived from He I 10 830 Å inversions). The gray shaded area indicates the umbra region. The vertical dashed line corresponds to the location plotted in the bottom panel. Bottom panel: vertical stratification of the median photospheric magnetic field inferred with the Si I 10 827 Å line at a selected umbral location.