Amplitude and phase distributions of the frequencies f₁ (left) and f₂ (right) across the Si III 4552 Å profile. Points with error bars are observations, while full lines are theoretical distributions. In the left panel, models for (l, m) = (0, 0) (red line) and pole-on (l, m) = (1, 0) (blue line), which are indistinguishable at the plotting scale, are shown. In the right panel the theoretical curve corresponds to (l, m) = (2, 2). The amplitude is expressed in units of continuum and the phase in 2π radians.