Estudo da turbulência atmosférica na floresta Amazônica - análise de dados micrometeorológicos e modelagem numérica

Abstract

In this work, a study of atmospheric turbulence at the Amazon forest is done through the analysis of nocturnal turbulence data and numeric modeling using a single column model. Important issues in micrometeorology are discussed: the role of non-turbulent scales to the exchange of scalars between the forest and the atmosphere, that are enhanced at night, may be larger in magnitude than their turbulent counterpart, and the role of atmospheric boundary layer processes to transport and redistribute chemical species, as NO, NO2 e ozone, following deep convection events. In the first, a comparison of scalar flux cospectra within and above the forest is done, aiming to analyse the contributions of non-turbulent flow to the total flux in different heights. Non-turbulent fluctuations are responsible for a large portion of the variability observed on intermittent nights, as the low frequency dominates over the turbulent transfer. Within the canopy, CO2 and latent heat fluxes are dominated by large scale processes. The fluxes calculated with longer time scales are more dependent on stability over a deeper layer above the forest than the stability between the forest top and its interior, suggesting that the low frequency processes are controlled over a deeper layer over the forest. In the second, we reproduce the dynamics of the atmospheric boundary layer following convective storms in Amazonia, focusing on physical processes that happen in these situations, evaluating the relative importance of turbulent and chemical proccesses to the ozone mixing ratio at the surface. To this, a single column model that solve the turbulent transport at the atmospheric boundary layer is used. Equations to the basic photochemical cycle of NO2, NO and O3 are incorporated to this model. The model was able to reproduce the variations of the ABL height and the recovery of ABL after storms. Furthermore, the model reproduced the evolution of ozone mixing ratios at the surface after convective storms.