Turbulent transport scales and breakdown coefficient statistics over a deforested tropical site

The study of breakdown coefficients (Novikov, 1990) allows inferences about the self-similarity and scale-invariance of a phenomenon that is supposed to be governed by an underlying multiplicative cascade process. The study of the structure function (Frisch and Parisi, 1985) of turbulent velocities indicates the presence of multifractality. Further studies on wind-tunnel turbulence data (Arneodo, 1998) focus on the statistics of breakdown coefficients and on the asymptotic validity of the scaling description. Such theoretical scaling functions will be contrasted with those derived from high frequency tower turbulence data and tethered balloon wind speed profiles obtained over a deforested site in Rondonia, Brazil, as part of NASA TRMM/LBA experiment (January and February, 1999). Length and time scaling parameters within the surface layer will be determined using the tower turbulence data. Tether sonde data will be used to examine how these features behave in the deeper mixed boundary layer. A theoretical interest of this study is to verify whether the features observed at similar Reynolds numbers are being preserved, independent of lower velocities or higher boundary layer depths. Another interest is the verification of the multi-fractal scaling hypothesis and the determination of the breakdown coefficient statistics. The practical interest of this work consists in opening new possibilities of stochastic prediction of atmospheric processes, particularly concerning the transport of water vapor from the moist sub-cloud layer to the deeper atmosphere.