Wavelet analysis of coherent structures above and within the Amazon Rain Forest

Coherent structures in the temperature and velocity fields in the atmospheric boundary layer are responsible for a large fraction of the flux transport of momentum, sensible heat and latent heat.

The techniques based on the variances of the wavelet transform coefficients at different scales are used to determine the time scales of the coherent structures. After identifying the principal time scale of the structures, denoising type techniques are use to separate out the coherent structures at various scales.

These techniques are applied to the vertical velocity component, virtual potential temperature, the momentum and heat fluxes for the fast response sonic data collected simultaneously at different heights on the micrometeorological tower in the Rebio-Jaru Reserve (10 04'S, 61 56'W) during the LBA (Large scale Biosphere atmosphere experiment in Amazonia) during the wet season of January to March 1999. The structure and nonstructure parts of the signal and their properties are examined in detail. In addition, the size of the structures, and their contribution to the momentum and heat fluxes has been studied. The variation of the coherent structures with the time of the day and with height, is investigated. Spectral estimates for each of the structure and non-structure part are compared with the non-partitioned signals. The information is used to characterize the turbulence above, within and below the forest canopy.

Preliminary results indicate that the time scales corresponding to structures identified in the thermal field appear to be consistently greater than those associated with the vertical velocity field.