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The spectral pattern of light attenuation in the ultraviolet (UV) and blue region (360–500 nm) was analyzed for seven high Arctic lakes. The best description of K_d versus wavelength was obtained with an exponential model similar to the model used for absorption by chromophoric dissolved organic compounds (CDOM), but with an additional parameter (K_back) that accounts for background scattering: where K_d(λ) is the diffuse vertical attenuation coefficient at wavelength λ and S is the exponential slope parameter that characterizes the decrease in attenuation with increasing wavelength. The inclusion of the background parameter gave a significantly better fit and eliminated the systematic deviations over the spectrum that occur in the absence of K_back. The resultant S values (mean = 17.4 µm⁻¹) were on average 47% higher than values calculated without a background parameter, and were more sensitive to …