The reflectance and negative polarization of light scattered from snow surfaces with different grain size in backward direction

- The scattering properties of snow surfaces were measured in backward direction.
- We described the phase angle dependence of reflectance and negative polarization of snow surfaces.
- The effect of grain size on the optical properties of snow surfaces was prominent.
- Based on the CB mechanism the relation between snow grain size and negative polarization can be explained.
- The result of this study is useful for understanding scattering property of high-albedo particulate surface.

The scattered light from particulate surfaces is useful for the verification of light scattering theory and the remote sensing applications. We present the photometric and polarimetric measurement results of natural snow surfaces with different grain size in the backward direction in field and in the laboratory. The snow grains are assumed that they exhibit both nonsphericity of shape and small-scale surface irregularities. All the samples display the prominent phenomena of brightness opposition surge and negative polarization; both of them are in dependence on the phase angle. There are clear effects of snow grain size on the photopolarimetric measurement results: the snow surfaces with small diameter show brighter reflectance than those of larger diameter, because of the amount of contaminants there is an exception of snow samples consist of small grain in the visible wavelengths; the absolute values of negative polarization increase with a decrease in grain size (corresponding to packing density), and the effect of snow grain size on negative polarization is quite significant in this study. The relation between snow grain size and negative polarization at near-backscattering geometries can be explained by the coherent backscattering mechanism. These results are useful to better understand the scattering property of high-albedo particulate surface with large particles.