The initial ice thickness and snow depth at the buoy deployment site were 1.53 and 0.15 m, respectively. The changes in ice thickness was determined using measurements by the underwater acoustic sounder. The measuring noise of the acoustic sounder has been removed. Since the acoustic sensor at the surface was invalid very soon after the deployment, the evolution of the air/snow interface was determined using the temperature profiles. Overall, the measurement accuracy was 0.1 K for temperature, 0.03 m for the snow or ice surface, and 0.01 m for the ice bottom, respectively. After the snow cover melted over, the negative values for the snow depth indicate the onset of ice surface melt.