Application of a simple model for ice growth to the Lake St. Moritz, Switzerland

We present a Simple Lake Ice Model to calculate the growth rate of lake ice in a cold and relatively dry climate. The focus is on Lake St. Moritz, Switzerland, which has an area of 0.78 km(2) and is about 45 m deep. In winter the lake is extensively used for recreational purposes, including horse racing with thousands of spectators. Safety on the ice cover is essential, and there is a great need to have a simple tool with which the growth rate of the ice layer can be calculated for given meteorological conditions. The approach is based on a simple formulation of the upper temperature of the ice layer, which depends on air temperature and snow cover. Input data are the date on which the lake freezes over, daily mean air temperatures and snow depth. For the winter 2021/22 calculated ice growth compares well with ice thickness measurements. We demonstrate that grooming of the snow has a significant positive effect on the ice thickening rate. We also evaluate the sensitivity of the simulated ice thickness to increasing mean temperature.

Automated summary

We propose a Simple Lake Ice Model to calculate the growth rate of lake ice in a cold and relatively dry climate. With a focus on Lake St. Moritz, Switzerland, we provide a tool that can calculate the growth rate of the ice layer based on air temperature, snow cover, and other input data. We also demonstrate the positive effect of grooming the snow on the ice thickening rate and evaluate the sensitivity of simulated ice thickness to increasing mean temperature.