Mean over 30 realisations of layer 2 WST coefficients S₂(j₁, j₂, ∆θ) (see text) for initial conditions (green), the reference simulation (blue) at about a third of a turnover time (t = 2), and MuScaTS basic syntheses over a time t = 2 (red). The main length scale runs from its index j₁ = 0 (smallest) to j₁ = J − 3 = 7. The secondary scale j₂ is labelled by ∆j = j₂ − j₁. The relative angle ∆θ runs from 0 to π from left to right in each broken line of fixed j₁ and ∆ j. The width of the lines indicates the standard deviation of this mean over our 30 realisations, the computational domain, and the absolute angle θ₁.