We studied the turbulent interactions among vertical wind velocity and temperature time-series measured in the Amazonian forest, during the wet season campaign of Large Biophere-Atmosphere Experiment in Amazonia (LBA) in 1999. The approach is based on the estimation of the correlation coefficient between the different scales in turbulent fields and Cross Wavelet Power (XWP). The results suggest that the correlations among scales of the vertical wind velocity are due to the Coherent Structures (CS), a large scale signature in the thermal profile. These coherent structures, kind of ramps, promoted an increase in the interaction among both variables, vertical wind velocity and temperature, and also depends on the atmospheric stability conditions. Furthermore, these coherent structures may explain the higher values of the correlation coefficient found in the large scales during the diurnal period compared with the nocturnal period, for the vertical wind velocity.

O objetivo deste trabalho é demonstrar, dentro de um contexto histórico, a necessidade de se usar a transformada em ondeletas. Experimentos computacionais simples são usados para explicar o surgimento desta ferramenta matemática. O programa utilizado neste trabalho está disponível na Internet.

The aim of this work is to show, within an historical context, the need of the wavelet transform use. Simple computational experiments to explain the origin of this mathematical tool are used. A home-page is available for download of the software program.

We perform statistical and wavelet analysis of three time series based on the solar wind velocity of the year 2000, the original time series and two filtered components. We use the Haar Wavelet Transform to separate this annual time-series into two parts, corresponding to high and low frequencies. We then calculate the kurtosis and skewness parameters for the three time-series. The results show that these parameters present high values in the low-pass filtered time-series, indicating that the intermittence level is superior at large scales (low-frequencies) if compared with the small scales of the turbulence. It is possible to conjecture that the Coherent Structures are responsible for this behavior. The use of the Morlet Wavelet Transform is presented to understand this behavior in terms of the gradient and nonlinear interaction of energy between scales.

É mostrada uma análise em ondeletas aplicada em um sinal geofísico, número de manchas solares. Para isso, é dado uma introdução teórica sobre a Transformada em Ondeletas e sobre séries e Transformada de Fourier. A Transformada em Ondeletas é uma ferramenta matemática de grande utilidade aplicação em sinais não-estacionários.

A wavelet analysis applied in geophysical signal, sunspot number, it is shown. For this, it is given a theoretical introduction about the wavelets Transform and Fourier Transform and Series. The Wavelet Transform is useful mathematical tool for application in non-stationary signals.