Interval 1. Top: train of rotational discontinuities/steepened Alfvén waves observed inside the low field region B (corresponding to interval 1 in panel g of Fig. 3). The red and blue lines encode the density n and magnetic field B, respectively, and B-components are shown in MVA (B_max = black, B_int = orange, B_min = green). Middle: larger interval around the event of the top panel, showing the presence of a counterpropagating packet, with wave-front steepened in the opposite direction and detected earlier by the s/c. Bottom: larger interval containing the wave packets, showing that they are located on a magnetic and density gradient connecting a region of very low field B. In this panel, the black line corresponds to B_R.