Averaging kernel for the inversion for the longitudinal flows at the target depth of 0.5 Mm. Top row: Horizontal cuts at the target depth. Bottom row: vertical cuts at y = 0. Columns from left to right: localisations of the longitudinal flows, latitudinal flows, vertical flows, and sound-speed perturbations. The red curve corresponds to the half-maximum of the target function at the target depth. The green full, the blue full, and the blue dotted curves correspond to the half-maximum, +5%, and −5% of the maximum of the averaging kernel at the target depth, respectively.