Correlation coefficients between the parameters (500 Monte-Carlo realizations) for the isotropic model (u_x, n = 0 for all n) and for the isotropic model except with u_x = 400 m s⁻¹ for the n = 3 peak (on the next page) at ℓ = 492 (k_pix = 21). Each box indicates the parameters for n-th peak (n = 0, 1, …5), q_i, n (i = 0, …6, from left to right and from bottom to top in each box) and the background parameters (BG). As we defined in Sect. 2q_0, n = ν_n is the frequency of the n-th peak, q_1, n = A_n is the amplitude, q_2, n = Γ_n is the width, q_4,n) = u = (u_x,n, u_y,n) is the horizontal velocity, q_5, n = f_c, n and q_6, n = f_s, n are parameters to handle anisotropy. Background parameters are q_0, BG = B₀ is the amplitude, q_1, BG = b is the power-law index, q_2, BG = f_c, bg and q_3, BG = f_s, bg are the parameters to handle the anisotropy of the background. Color scale is shown by the color bar on the right side. We note that the last columns and rows (i = 4) of BG on the top panels are empty because the number of the background parameters in the model in the updated code is four, instead of five.