Perpendicular Fourier spectra of v_x and v_y velocities measured in the leading maximum of the z⁻ wave. Top row: λ_⊥ = 0.8; middle row: λ_⊥ = 2; bottom row: λ_⊥ = 3. Left: v_x of the setup with the z⁻ wave only; middle and right denote v_x and v_y of the setups after AWs collision. In each panel, the (x, y)-coordinates represent corresponding Fourier wave numbers, and the color shows intensity of a given spectral component. The quasi-logarithmic color table is normalized to the amplitude of a harmonic wave.