A mathematical model of dissolved oxygen transport during the thermal bar evolution

The article describes а 2.5D non-hydrostatic model of dissolved oxygen transport in a freshwater lake. The oxygen dynamics are carried out through oxygen exchange with the atmosphere and physical transfer due to the effect of the thermal bar. An intraday change in wind speed (that influences the rate of oxygen transition from gas to liquid) is taken into account at the air-water interface. Space-time distributions of temperature and dissolved oxygen concentration were obtained during the spring thermal bar on an example of Barguzin Bay of Lake Baikal. The results of simulation showed that the vertical flows generated by the spring thermal bar contributed to an increase in dissolved oxygen content in the thermoactive region of the bay. Due to the action of the thermal bar, areas with different levels of oxygen are formed in the body of water. There is not only a quantitative but also a qualitative difference between the oxygen distributions obtained for the thermoactive and the thermoinert regions. It has been also found that the wind speed and the wind duration affect the oxygen saturation of water at the thermal bar. The results of this study confirm the barrier function of the thermal bar.