| Summary: | É feito um estudo da camada limite da atmosfera perto do solo. O escoamento turbulento do ar e o problema fundamental da micro-meteorologia. Sao analisados dois perfis de vento de Monin-Obukhov e de Swinbank. Deste estudo resultam relações universais do parâmetro de de Monin-Obukhov com a estabilidade do ar. O perfil de vento de W.C.Swinbank e modificado com a introdução do numero turbulento de Prandtl como função da estabilidade e altura acima do solo. E proposto um modelo físico-matematico para determinação do numero turbulento de Prandtl com resultados satisfatórios. === Heat flux determination in the turbulent boundary layer through wind speed profile measurements turns up to be possible. From a definition and a hypothesis the form of the wind profile in a turbulent boundary layer when the air is thermally stratified is derived by Swinbank. This models is tested for near-neutral stable and unstable conditions. Swinbanks exponential profile is at most valid for unstable wind profile. It is very difficult to apply this exponential profile in, the case of other stability conditions. With a view to obtain good results in near-neutral and stable conditions the exponential wind profile is derived using Panofsky's scale length L and the ratio KH/KM for eddy diffusivity coefficients of .heat and momentum. We consider a simple model to account for the variation of KH/KM with height and stability parameter z/L. This new exponential profile gives better results for sensible heat flux in the case of near-neutral and stable conditions. The variation of Monin-Obukhov parameter with stability is also examined. The parameter is highly variable for near-neutral conditions. The log-linear law is also examined in the range of Richardson number between -0,005 to -0,03 assuming the similarity of profiles. These results further show that it is possible to predict sensible heat flux from the Monin-Obukhov universal ( ) functions without reference to transfer coefficients in this range of instability.
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