Image analyses and modeling were carried out on blue coloration of Aoike Pond, Aomori Prefecture. In a theoretical model, it is assumed that the blue coloration occurs by light absorption of water before and after irregular reflection at lake bottom and by light absorption of water before and after light scattering with the dependence on wavelength. A comparison between analytical results of images and simulated results by the model revealed that both the irregular reflection at bottom and the water-density fluctuation scattering (or molecular scattering) contribute to the blue coloration. The optimization of parameters in the model allowed us to separate the two contributions where the irregular reflection and the density fluctuation scattering produce greenish colors with blue and deep blue colors, respectively. In the simulation including “Aoike color chart”, the maximum depth of Aoike Pond at 8.8 m proved to be responsible for the existences of the irregular reflection and density fluctuation scattering with the magnitude of same order for contributions to blue coloration.

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