Modelling the evolution of the nocturnal boundary layer for three different nights in CASES-99

This study presents a comparison of model results with detailed observations from the CASES-99 experiment for three nights with rather different atmospheric characteristics (fully turbulent, intermittent turbulent and non-turbulent). We use a high resolution, one-dimensional model with prescribed dynamics from observations and mesoscale analysis. The model utilizes first order turbulence closure, a grey body approximation radiation scheme and refined descriptions for the coupling of the atmosphere to the land surface and heat diffusion in the soil. Despite the totally different atmospheric characteristics of the three nights, the model is able to predict the major variables and the evolution of the stable boundary layer well. Especially the evolution of the vegetation temperature, soil heat flux and the sensible heat flux during the transition from day to night is simulated correctly. To represent the observed fast response of surface temperature, the model needs high resolution in the soil as well as an explicit description of vegetation.