LAKE

LAKE is an extended one-dimensional model of thermodynamic, hydrodynamic and biogeochemical processes in the water basin and the bottom sediments (Stepanenko and Lykosov 2005, Stepanenko et al. 2011). The model simulates vertical heat transfer taking into account the penetration of short-wave radiation in water layers (Heiskanen et al., 2015), ice, snow and bottom sediments. The model allows for the evolution of ice layer at the bottom after complete lake freezing in winter. The equations of the model are formulated in terms of quantities averaged over the horizontal section a water body, which leads to an explicit account of the exchange of momentum, heat, and dissolved gases between water and the inclined bottom. In the water column, k−ϵ parametrization of turbulence is applied. The equations of motion take into account the barotropic (Stepanenko et al., 2016) and baroclinic pressure gradient (Степаненко, 2018). In ice and snow, a coupled transport of heat and liquid water is reproduced (Volodina et al. 2000; Stepanenko et al., 2019). In bottom sediments, water phase changes are simulated. The model also describes vertical diffusion of dissolved gases (CO2, CH4, O2), as well as their bubble transfer, methane oxidation, photosynthesis and processes of oxygen consumption. Parameterization of methane production in sediments is included (Stepanenko et al. 2011), and for the case of thermokarst lakes, an original formulation for the methane production near the lower boundary of "talik" is implemented. Model was tested in respect to thermal and ice regime at a number reservoirs in contrasting climate conditions, specifically, within the LakeMIP project (Lake Model Intercomparison Project, Stepanenko et al., 2010; Stepanenko et al., 2013; Stepanenko et al., 2014; Thiery et al., 2014).