The lake-air exchange simulation of a lake model over eastern Taihu Lake based on the E-ε turbulent kinetic energy closure thermodynamic process

A lake model based on the E-ε turbulence closure thermodynamic process combined with the effect of submersed macrophytes is adopted to simulate lake-air exchanges over eastern Taihu Lake in August 2013. The observational data collected at the station over the Taihu Lake are used to verify the model results. The simulated water temperature and sensible and latent heat fluxes are in good agreement with observations. RMSEs of water temperature and sensible heat flux are less than 1℃ and 54.7 W/m2, respectively. Because the lake is shallow, the stratification of the water temperature can be easily affected by weather conditions. The thermal stratification is significant under sunny condition with weak winds. The temperature difference between the lake surface and the bottom of the lake is 7.9℃ when the wind speed is 0.8 m/s. High wind speeds can drive strong vertical mixing in the lake, and lead to the disappearance of the thermal stratification. When the wind speed is 12 m/s, the temperature difference between the lake surface and the bottom of the lake is only 0.12℃. Submerged macrophytes can increase the extinction coefficient, reduce the internal heat in the lake, and add resistance to the movement of water, and subsequently influence the distribution of the turbulence kinetic energy and water temperature. In summary, this model can well simulate the lake-air exchange processes over the shallow lake.