S-curve of the MREF model at a radius of 0.2 AU. The black line corresponds to the evolutionary track during the quiescent phase, while the coloured dots are taken from snapshots during the outburst stage. The red data points were extracted during the first outburst and the yellow, green and blue dots make up the evolutionary tracks during the first, second and third reflare, respectively. The density of the dots along an evolutionary track indicates the velocity at which the disc evolves. The arrows are exemplary for the first two cycles and indicate the direction in which the model evolves. The surface density value at which the disc switches from the upper branch (where α = α_MRI) to the lower branch (where α = α_DZ) is the same for each cycle and is marked with ${\mathrm{\Sigma }}_{\text{crit\hspace{0.17em}}}^{\min }$.