[M-IS10] Mountain Science

[MIS10-P05] Relationship between spectral reflectance and snow algae on snowpacks in Mt. Gassan, Yamagata prefecture, Japan

*Ryohei Abe¹, MASATO ONO¹, Nozomu Takeuchi¹ (1.Chiba University)

Keywords:Mt. Gassan, Colored snow, Snow algae, Spectral reflectance

Snow algae are photosynthetic microorganisms growing on the surface of glaciers and snowpacks. Because the cells of snow algae contain a variety of pigments, snow surfaces on which they grow are green or red and are called green snow or red snow. These are called green snow and red snow and are collectively called colored snow. The visible light spectral reflectance of colored snow shows unique spectra depending on the number of algae in the snow and ice and the type of pigment. However, since snow algae have a variety of pigments, the detailed relationship between the spectral reflectance and the snow algae has not been clarified. In this study, This study aimed to clarify the relationship between the spectral reflectance of snow-colored snow and algae on the surface of snow-colored snow by using the snow-colored snow phenomenon at Gassan, Yamagata Prefecture, where snow-colored snow of various colors can be observed. The spectral reflectance of red snow and green snow showed characteristic shapes. The spectral reflectance of red snow and green snow showed two regions of reduced reflectance, one at 675 nm and the other at 450 nm. There was a significant positive correlation between the difference in reflectance at 700 nm and 675 nm and the concentration of chlorophyll-a in the snowpack. The regression line of the relationship between the reflectance at 700 nm and 675 nm and the concentration of chlorophyll-a in snow and ice can be determined. The decrease in reflectance at short wavelengths is attributed to the absorption of chlorophyll-a, chlorophyll-b, and primary carotenoids in snow and ice algae cells. On the other hand, the reflectance decrease in red snow is characterized by a wider wavelength range than that in green snow, which is due to absorption at longer wavelengths. There was a significant positive correlation between the difference in reflectance at 600 nm and 550 nm and astaxanthin concentration in red snow. Using the regression line of the relationship between the two, the concentration of astaxanthin in red snow could be quantified. Based on the quantitative relationship between the above spectral reflectance and the concentrations of chlorophyll-a and astaxanthin, we developed a scatter plot that can simultaneously quantify the amount of snow and ice algae and discriminate between red snow and green snow using spectral reflectance. By measuring the surface reflectance spectrum of the snow surface and plotting the results on this scatter plot, it should be possible to discriminate red snow from green snow and quantify the number of algae without detailed analysis.