MODELING HEAT TRANSFER DURING SOLAR-INDUCED MELTING OF LAKE AND SEA ICE

Abstract

Solar heating and ice melting on the water surface is an important geophysical problem that has attracted the attention of researchers for many years. It is essential in connection with global climate change on our planet. A simple and sufficiently accurate physical model of the process is proposed, combining analytical solutions for the solar radiation transfer in light-scattering snow cover and an ice layer with numerical calculations of transient heat transfer in a multilayer system. The boundary conditions for the heat transfer problem consider convective heat losses to the cold air and radiative cooling of the open surface in the mid-infrared window of transparency of the cloudless atmosphere. Much attention is paid to modeling the anomalous spring melting of ice covering the large high-mountain lakes of Tibet, the Earth's third pole. It was found that a thick ice layer not covered with snow starts to melt at the ice-water interface due to the volumetric solar heating of ice. The results of the calculations are in good agreement with the field observations. The computational analysis shows a dramatic change in the process when the ice surface is covered with snow. A qualitative change in the physical picture of the process occurs when the snow cover thickness increases to 20-30 cm. In this case, the snow melting precedes ice melting and water ponds are formed on the ice's surface. This is a typical situation for the Arctic Sea ice cover during the polar summer. Known experimental data are used to estimate the melting of sea ice under the melt pond. Positive or negative feedback related to the specific optical and thermal properties of snow, ice, and water are discussed.