Schematic sketch of the KH waves based on the average normal directions of the inbound and outbound crossings and the shear flow direction (maximum variance direction of V) in the R − T plane. The flow directions on Side 1 and Side 2 correspond to the velocity perturbation vectors outside the wave-like interval in Fig. 8f. The shear flow direction is nearly perpendicular to the wave edge normals, which can be interpreted as wavy structures developed within the velocity shear layer consistent with KH waves.