Riblets along the F1 ribbon. All panels show the same FOV, highlighting the central parts of the eastern ribbon. All panels except panels c–d show images in the Hβ +0.8 Å channel. Panel c shows the wing-subtracted colour map at Hβ ± 0.8 Å. Panel a shows the ribbon with identified riblets overplotted in green, red, or cyan. Green pixels represent single-peaked RPs, red pixels represent double-peaked RPs with a stronger red peak, and cyan pixels represent near-symmetric double-peaked RPs. Similar is shown in panel d overplotted on the Hβ core image. The resulting Doppler shifts and profile widths obtained from fitting the pixels are shown in panels e–f, respectively. The black pixels in panel e mask the pixels where blue shifts were estimated. The contours of these pixels are added in panel c. An animation related to this figure is available online.