Figure 8.

Spectra obtained during transect 1 illustrating the contrasting spectral reflectance of snow (site S1a), clean ice (0 algal cells ml⁻¹, Site S3) and algal ice (0.76 ± 0.19 × 10⁴ algal cells ml⁻¹, Site S3). HCRF = hemispherical conical reflectance factor, obtained by measuring light reflected from the surface relative to a Spectralon white reference panel. Reference panels can be less reflective than fine grained snow at nadir, explaining reflectance values >100%. Data are presented as a proxy for albedo, though correction for the viewing angle and surface anisotrophy are required to calculate albedo from these data (see Cook et al. 2017).