Numerical Simulation of Ice Cover of Saline Lakes

Resumo

A new version of the one-dimensional thermo-hydrodynamic and biogeochemical model LAKE2.1 is presented. The model is supplemented with a description of the dynamics and vertical distribution of salinity in an ice cover. Simulation results are compared to in situ and satellite data of water temperature and ice cover at Uvs Nuur Lake (Mongolia) from 2000 to 2015. It is shown that underestimating the mixed-layer depth by the model with standard turbulence closure k−ε during summer and autumn leads to a significant shift in the timing of the onset of ice. It is also demonstrated that, while neglecting the salinity of the lake, the freeze-up according to the model happens 16–17 days earlier than in reality. This error is removed if the effect of salinity on water density and freezing temperature is included. However, in this case, the model underestimates the maximal seasonal ice thickness on average by ≈0.2 m. In turn, this error decreases an order of magnitude if the dynamics and vertical distribution of salinity in ice are simulated in the model.