Image Analysis of Snow Internal Structure Observed by Ground Penetrating Radar

Abstract

We studied the internal structure of snow by conducting a Ground Penetrating Radar (GPR) survey which has used for the study of the ground structure and the site in the past. First, the laboratory experiment was conducted to study variations in the radio wave's reflection patterns of the internal structure of snow at the Snow and Ice Research Center of NIED. Ice layers and water channels were created in an artificial snow block, and the reflections of radio waves under various conditions were analyzed. In the water channel, it was found that the formation of air spaces by the flow of water caused stronger reflection of radio waves, but when the flow of water increased and the air spaces were filled, radio waves weakened. Also, it could be confirmed the ice layer within the snow was appeared as the strong reflection. Next, GPR field survey was conducted to study the time-change of snow structure at the Murodo region in the Mt. Tateyama during the snowmelt season. In 2007, the internal structure of snow was surveyed over a wide range. From this survey, the changes in the internal structure of snow during the snowmelt season could be identified by the repeated investigations, and the distribution of the snow depth and the snowmelt process could be studied using two dimensional data. In 2008, GPR survey was conducted in the same area to acquire three-dimensional data, which enabled us to estimate the disappearance of ice layers and the route of water channels. These results show that the analysis data of GPR survey are appropriate for the assessment of the internal structure of snow.