Thermobaric stratification in a very deep, horizontally homogeneous lake

This is the numerical representation of an idealized model of an horizontally homogeneous lake. The program is intended to demonstrate the forming of a thermobaric stratification as it is seen for example in Lake Shikotsu (Hokkaido, Japan). This model however, is not based on real boudary conditions. The user can control the boundary condition of the surface temperature, and the model calculates the resulting temperature stratification.

  • The idealized lake is 500m deep
  • The horizontal cross section possesses the same area on every depth (e.g. cylindrical basin)
  • Pure water, no salt nor salt gradients are considered.
  • The user controls the surface temperature by pressing "+" or "-"; i.e. increase / decrease by 0.01K
  • "10+" and "10-" indicate 10 loops
  • After each loop, the model checks density stability
  • If unstable, neighbouring boxes are mixed, and receive average temperature of previous layers except at surface, implemented surface temperature is enforced
  • Constant diffusivity is implemented; some geothermal heat input

sorry:  not available any more

What can be learned?

  • In very deep lakes, autumn deep mixing and springtime deep mixing are not symmetrical.
  • A homogeneous deep water body can be formed.
  • In early spring the profile follows the temperature of maximum density profile closely.
  • no partial deep water renewal is required to form the profiles.

If you use this model, please refer to below mentioned paper, which shows results of an earlier version: