Visualization of structural and textural changes in the newly formed snow layer during prolonged snowfall

Abstract

Observations were made on the dynamics of structural and textural transformations in the newly fallen snow layer during its transition to a stratigraphically significant snow accumulation layer. To visualize the structural and textural transformations during a prolonged snowfall and post-sedimentation changes in it after the snowfall stopped, a reflective screen was used in combination with photomicrography of solid precipitation and snow grains. Observations were made for seven days. Already on the third day, with the thickness of the newly formed snow layer of 12 cm, the primary texture in the form of internal layering, due to the microstructure of freshly fallen snow, began to differ in it. In the process of post-sedimentation transformations, the primary stratification in the newly formed stratigraphically significant snow layer was preserved, but became less noticeable. Micrographs showed that the deposited snowflakes were transformed by sublimation metamorphism to form small rounded RGsr particles, which differed little from the snow grains in the underlying layer. It is assumed that the structural and textural post-sedimentation transformations of solid precipitation in the upper part of the snow thickness are more controlled by the depth of penetration of the air temperature gradient. Lower boundary of this upper part is well distinguished in the snow profile owing to the optical anisotropy of the snow horizons composed of RGsr snow grains and FCso and DHla facet crystals. The performed studies demonstrated that the light-reflecting screen can be used in snow science as a simple tool for optical monitoring of structural heterogeneities of seasonal snow cover and visualization of post-sedimentation processes that occur during its growth.