Top panel: aerosol phase function as a function of scattering angle for the most likely models at two different wavelengths, 0.5 and 1.5 μm. For Run A, alternate optimal functions (dotted and dashed-dotted) are also shown, which are the same calculations but excluding the 90 and 110° observations for both wavelengths. Also shown is the phase function used in the current sky background model (default) and with uniform probability L_i = 1 in Eq. (6). For clarity, the middle panel shows the three runs relative to the uniform probability phase function. Bottom panel: relative error σ_x/< x > from Eq. (6).