A predictive numerical model of the atmospheric boundary layer based on the turbulent energy equation

• The atmospheric boundary layer has come into the focus of interest in recent years. Many areas of activity are dependent on accurate information about the boundary layer and prediction of its state. This is true in local weather forecasting, air pollution control and wind energy production. The thesis deals with the development of an one-dimensional numerical model of the atmospheric boundary layer. In the first part the model equations are derived and two different formulations discussed, one is based on an approach outlined by Gutman and the other is a more conventional Ekman formulation. A central part deals with the question of turbulence closure. The turbulent energy equation is derived in a version including condensation processes. Different mixing length formulations are also discussed. Other physical processes as radiation, condensation and soil heat transfer are also included in the model. The numerical integration is carried out using centered differences in the vertical in a stretched coordinate system and the Laasonen’s scheme in time. The model has been tested on two sets of boundary layer data, one from SE Australia and another from southern Finland, with different assumptions in using the two versions of the model. Results indicate that the turbulence parameterization used performs very well and as well as so called higher order closure schemes. The Ekman formulation seems to perform better than the Gutman version when observed data are simulated (hindcast). Conclusions and suggestions for improvements and further work conclude the thesis. 

Ämnesord

NATURVETENSKAP  -- Geovetenskap och miljövetenskap (hsv//swe)

NATURAL SCIENCES  -- Earth and Related Environmental Sciences (hsv//eng)

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