Some theoretical and experimental aspects od the surface layer above the "Pantanal Matogrossense" / Alguns aspectos teoricos e experimentais da camada limite superficial acima do Pantanal Matogrossense

AUTOR(ES)
DATA DE PUBLICAÇÃO

1999

RESUMO

In this study it was used data from the micrometeorological tower located at Miranda city ( 19 degree 6 S 5 degree 0 W), in the Pantanal Matogrossense, in order to characterize aspects of the structure of turbulence in the atmospheric boundary layer, in the transition period between wet and dry seasons. The Wavelet Transform was used in the analysis of the turbulent signals, which allowed the high-pass filtering of the turbulent data and the obtained time-scale diagrams showed interesting aspects of the variability of covariance contribution to turbulent fluxes in different scales. It is possible that the semi-flooded Pantanal characteristics favor the presence of local circulations, and as a consequece, low-frequency flutuations, makes difficult to define accurately the spectral flaw and the separation between the average and turbulent flutuation. The data taken from the slow response instruments showed some discrepancy compared to the relations established by the Monin-Obukov Similarity Theory, specially concerning the momentum exchanges under unstable conditions, probably due to the transition sublayer. The data measured from fast response instruments, taken above the transition sublayer, presented good agreement compared to the parameterizations of turbulent momentum of second order. The complex characteristics of the terrain were not totally isotropic and the displacement height of the zero-plane, calculated by the De-Bruin and Verhoef method, changed according to the average wind direction, The infomation given by the turbulent spectra of the horizontal components of velocity allowed a good estimation of the mixed layer height for unstable conditions, utilizing the methodology proposed by Liu and Ohtaki.

ASSUNTO(S)

estudos do sinal geofisico camada limite superficial pantanal umido fluxos teoria da similaridade transformada em ondeletas variancia turbulencia

ACESSO AO ARTIGO

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