Modified parameterization of the vertical water temperature profile in the FLake model

Abstract

The lake model FLake is currently widely used in numerical weather prediction and in climate models to parameterize the effect of freshwater lakes on the state of the boundary atmospheric layer. The model is based on a two-layer parametric representation of the evolving temperature profile (ETP) and on the integral budget of energy for the layers in question. The structure of the stratified layer between the upper mixed layer and the basin bottom is described using the concept of self-similarity of the temperature-depth curve. Capacity of a function of such type to simulate ETP accurately defines the model quality, that is, the extent of correspondence between numerical results and observational data. Several self-similar temperature-depth curves either obtained analytically or resulted from observational data handling, have been used in earlier FLake modifications with different extent of advance. The main shortcoming of parameterizations used previously was their inability to reproduce all types of the ETP known from observations. In the present study, a new parameterization of ETP in frames of FLake, also based on self-similarity of the temperature-depth curve, is proposed. It is demonstrated that a new parameterization is capable to reproduce most of the ETP types observed, whereas the self-similar functions proposed earlier are found to be its particular cases.

Keywords

• numerical weather prediction
• climate models
• parameterization of lakes
• FLake model
• vertical temperature profile
• self-similarity