Model fit for the OH doublets in Mrk 231. The blue, light-blue, dashed light-blue, and green curves show the contributions by the quiescent component (QC), high-excitation outflow component (HVC), low-velocity component (LVC), and low-excitation component (LEC), respectively. Red is the total emission and absorption due to all components. In this specific model, the parameters for the HVC are T_dust = 105 K, R_int = 74 pc, R_out/R_int = 1.3, N_OH = 1.6 × 10¹⁷ cm^-2, v_int = 1700 km s^-1, v_out = 100 km s^-1, and p_f = 1.15 × R_int, and the mass-outflow rate per unit of solid angle is dṀ/dΩ ≈ 100 M_⊙ yr^-1 sr^-1.