DECAIMENTO DA TURBULÊNCIA NA CAMADA SUPERFICIAL

AUTOR(ES)

Luiz Eduardo Medeiros

DATA DE PUBLICAÇÃO

2005

RESUMO

This dissertation presents a study of the atmospheric turbulence decay on the surface layer during the evening transition. This is done through the analysis of the spectral densities temporal evolutions of the three wind components, observed at a micrometeorological site in the central region of Rio Grande do Sul state, Brazil. From the observed spectra, the shapes and types of turbulent decay are determined. The decay happens as a consequence of the decrease in the two types of forcings that are responsible for turbulence production: mechanical (vertical wind shear) and thermal (surface sensible heat flux). Results show that surface layer turbulence decay does not follow an organized pattern, due to the existence of the different forcings, specially the mechanical one. The convection-related spectral peak tends to vanish as the transition goes on, but the mechanical peak remains important if the surface winds are appreciable. The temporal evolutions of the spectral components are also employed for a comparison with the model from Goulart et al. (2002) for the decay of a homogeneous turbulence. This is done through the comparison of the three-dimensional observed spectra to those generated by the theoretical model. The three-dimensional observational spectra are obtained by the employment of Kristensen et al. (1989) model. This model provides a method for the determination of the three-dimensional spectrum from the one-dimensional components, for homogeneous turbulence. The comparison shows that a reasonable adjust only happens in the case of a surface layer completely controlled by the thermal forcings. If a mechanical production of turbulence exists, the model is not capable of reproducing the observations.

ASSUNTO(S)

fisica pico espectral período de transição forçante térmico forçante térmico período de transição pico espectral espectro forçante mecânico forçante mecânico espectro

Documentos Relacionados

• Análise de ondaletas aplicada a sinais de turbulência na camada limite superficial
• Parametrização do decaimento da turbulência na camada limite convectiva
• MODELO ESPECTRAL DE HEISENBERG APLICADO AO DECAIMENTO DA TURBULÊNCIA NA CAMADA RESIDUAL
• x
• Transporte turbulento na camada superficial da atmosfera em condições diabáticas