Line-of-sight (LOS) and plane-of-sky (POS) velocities of the flare and the cool component of the jet. Panel (a) shows the Doppler velocity diagram at 14:45:55 UT. Panels (b)–(d) show the temporal evolution of the POS velocity determined by FLCT. Panels (e)–(h) show Hα spectra observed by CHASE in the quiet region (Rq, the average spectral line of the black box in panel a), flare region (Rf), redshift (Rr), and blueshift (Rb) regions of the jet. Panels (i)–(k) show the net line profiles in Rf, Rr, and Rb. The dashed red lines indicate the 80% intensity of Rq, 20% intensity of the emission line of Rf, and the wavelengths corresponding to the intensity minimum of the red wing in Rr and the blue wing in Rb, respectively.