Abstract. The lake-rich Qinghai–Tibet Plateau (QTP) has
significant impacts on regional and global water cycles and monsoon systems
through heat and water vapor exchange. The lake–atmosphere interactions have
been quantified over open-water periods, yet little is known about the lake
ice thermodynamics and heat and mass balance during the ice-covered season
due to a lack of field data. In this study, a high-resolution thermodynamic
ice model was applied in experiments of lake ice evolution and energy balance
of a shallow lake in the QTP. Basal growth and melt dominated the seasonal
evolution of lake ice, but surface sublimation was also crucial for ice loss,
accounting for up to 40 % of the maximum ice thickness. Sublimation was
also responsible for 41 % of the lake water loss during the ice-covered
period. Simulation results matched the observations well with respect to ice
mass balance components, ice thickness, and ice temperature. Strong solar
radiation, negative air temperature, low air moisture, and prevailing strong
winds were the major driving forces controlling the seasonal ice mass
balance. The energy balance was estimated at the ice surface and bottom, and
within the ice interior and under-ice water. Particularly, almost all heat
fluxes showed significant diurnal variations including incoming, absorbed,
and penetrated solar radiation, long-wave radiation, turbulent air–ice heat
fluxes, and basal ice–water heat fluxes. The calculated ice surface
temperature indicated that the atmospheric boundary layer stratification was
consistently stable or neutral throughout the ice-covered period. The
turbulent air–ice heat fluxes and the net heat gain by the lake were much
lower than those during the open-water period.